The RenX Files: High idle problems

[8Mud]

I must agree, "Very Interesting" indeed!

I wonder if a precision resistor in one side to correct the imbalance would be worth investigating?

I have always just set the ECU side and pretty much ignored the TCU side. I am starting to wonder if that was a mistake. I am still getting less mileage than I think I should (10-12 local, maybe 15 to 16 highway), and have to get my speed up to 42 to 43 mph to get the last shift (4th or clutch lock up, not sure which it is yet, I am thinking 4th). If I go from zero to 35 and cruise at 35 mph I am still at 1800 rpm, if I go to 42 mph and drop back to 35 mph cruising the RPM is at 1100 to 1200 rpm.

When I quoted the 18% number that was fairly specific for my XJ, my input voltage for the ECU side of the TPS, is around 4.62 X .18 (18%) = .83.
But to get acceptable shifts and a decent idle. I set the ECU side at .75 volts (16.5%) and the TCU side at 3.8 volts and increased my gas mileage by 6%. My numbers are a bit plus/minus.
It has been mentioned in the past that 84% and 16% are the outside performance settings.
I just tried to set mine to shift with 30 inch tires I have (just a little late) and to idle somewhere between too high and too low (temperature dependent).
I was thinking maybe just a cross over wire between the TCU and ECU power IN wires and got a bit nervous about it. A diode loop would likely be a better solution.
My two power inputs a have a significant difference, all the units may not be the same. Renix electronics are fairly primitive. It's worth a look if you are having trouble getting the TPS dialed in though.
I got which side of TPS is which, bass ackwords, the ECU side is the three pole connector and the TCU is the four pole connector. I think I got that right anyway.

 

[Ecomike]

When I quoted the 18% number that was fairly specific for my XJ, my input voltage for the ECU side of the TPS, is around 4.62 X .18 (18%) = .83.
But to get acceptable shifts and a decent idle. I set the ECU side at .75 volts (16.5%) and the TCU side at 3.8 volts and increased my gas mileage by 6%. My numbers are a bit plus/minus.
It has been mentioned in the past that 84% and 16% are the outside performance settings.
I just tried to set mine to shift with 30 inch tires I have (just a little late) and to idle somewhere between to high and too low (temprature dependent).
I was thinking maybe just a cross over wire between the TCU and ECU power IN wires and got a bit nervous about it. A diode loop would likely be a better solution.
My two power inputs a have a significant difference, all the units may not be the same. Renix electronics are fairly primitive. It's worth a look if you are having trouble getting the TPS dialed in though.

I have to agree, tying those two power supply outputs together would be real risky!!!!!! They just might fight one another and burn themselves out in the process.

I have another option. I have been collecting working spare Renix ECUs and spare TCUs, I may just test out the different TCUs I have for volatge outputs and play with picking, matching the best one to my system. I am pretty happy with the current ECU I am using, but that could change as I do more testing.

I lucked out last year and bought a Matco MD-59 analyser on Ebay (mini laptop size, sold for about $8,000 in the late 80's) that I need to reuse and retest my Renix Engine beast with. I used it once last year, 12 months ago, and it said I essentially that I had a perfectly working new like, excellent running engine and ignition system (240,000 miles on it). It runs an osciloscope like test/program that gives you data on each cylinder and each fuel injector telling you if the injectors, cylinders, valves, spark, etc are working optimally or not. Electronically detects bad injectors, valves, bad compression, poor spark, etc. Hell of tool. Amasing the tests it can run and generate on a fuel injected engine.

 

[8Mud]

Question- is the TPS setting different for a manual than it is for an auto? I Chilton's doesn't differentiate, but I read another post that says it's .82 for auto, and .17 for manual?

The .82 is actually ? % of input voltage, the .17 is 17% of input voltage. If your input voltage was say 4.8 X .17 (17%) = .816 (.82 volts everybody refers to).
Clear as mud?
Don't get percents confused with voltages.
The .82 for the auto is actually 82% of input voltage and you ignore the other half of the TPS (ECU). I guess they figure the tranny adjustment is the more critical of the two.
But if the tranny adjustment, pushes the ECU half of the TPS out of the envelope, bad things can happen. There is some flexiblity built into the system. You have to figure the TPS input voltage values likely change a little anyway, as the alternator voltage changes. I doubt the IN voltage is perfectly stabilized.

 

[8Mud]

I have to agree, tying those two power supply outputs together would be real risky!!!!!! They just might fight one another and burn themselves out in the process.

I have another option. I have been collecting working spare Renix ECUs and spare TCUs, I may just test out the different TCUs I have for volatge outputs and play with picking, matching the best one to my system. I am pretty happy with the current ECU I am using, but that could change as I do more testing.

I lucked out last year and bought a Matco MD-59 analyser on Ebay (mini laptop size, sold for about $8,000 in the late 80's) that I need to reuse and retest my Renix Engine beast with. I used it once last year, 12 months ago, and it said I essentially that I had a perfectly working new like, excellent running engine and ignition system (240,000 miles on it). It runs an osciloscope like test/program that gives you data on each cylinder and each fuel injector telling you if the injectors, cylinders, valves, spark, etc are working optimally or not. Electronically detects bad injectors, valves, bad compression, poor spark, etc. Hell of tool. Amasing the tests it can run and generate on a fuel injected engine.

My method is the old butt dyno and simple multimeter tests. When something gets seriously out of wack, I notice pretty quick. My old XJ is a hard used 88, that I manage to barley keep up with. Though I have to say everything works, but the door locks (reliably), my headliner is slowly becoming a lap blanket and some oil seeps. Next project. I just managed to get the power windows to double there speed (last project), I'm fairly proud of that.

 

[Ecomike]

You just had to go and MUDdy up the water, LOL. Well some folks here love mud from what I hear.:roflmao:

Anyway, Good answer!!!!!!

I see where some confusion comes from as the .82 is also the idle voltage setting listing in one of the FSMs I have in pdf form, 89 year I think, and mine is 0.80 Volts, 87 year for the front, ECU side of the TPS. My 87 year FSM, Renix FI manual, says to set the ECU-TPS idle to 0.80 volts (apx) with the engine off and power on, which eliminates the alternator voltage regulator influence. It says nothing about the percentage values of input voltage at idle and WOT. It also says input volatge (pin A to Pin B of the front ECU connector) should be apx 5.0 volts.

It also says nothing about setting the TCU-TPS voltages or using percentages on the TPS using the square TCU to TPS connector.

But I have read here and elsewhere ( I forget where exactly) about the percentage setting procedure you and some others are using and I have read where some use the TPS-TCU connector for setting the percentage volatges.

I have just never tried it. Do you have any idea where the percentage method and the TCU-TPS settings originated????

The .82 is actually ? % of input voltage, the .17 is 17% of input voltage. If your input voltage was say 4.8 X .17 (17%) = .816 (.82 volts everybody refers to).
Clear as mud?
Don't get percents confused with voltages.
The .82 for the auto is actually 82% of input voltage and you ignore the other half of the TPS (ECU). I guess they figure the tranny adjustment is the more critical of the two.
But if the tranny adjustment, pushes the ECU half of the TPS out of the envelope, bad things can happen. There is some flexiblity built into the system. You have to figure the TPS input voltage values likely change a little anyway, as the alternator voltage changes. I doubt the IN voltage is perfectly stabilized.

 

[Ecomike]

Well I just collected some data on my power on, engine off,TCU-TPS square connection all at Idle:

A-B = .29 V
A-D = 4.36 V
B-D = 4.65 V

A-ground = 5.45 V
B-Ground = 5.16 V
D-ground = 0.80 V
---------------------------
Power off ohm readings:

A-Gorund = 550 ohms
B-ground = 1550 ohms
D-ground = 1355 ohms

A-B = 1025 ohms
A-D = 1074 ohms
B-D = 1963 ohms

I need an extra pair of hands or tool to run the tests at WOT. Maybe do that later. I was surprised to see all these resistance readings with the power off. I expected one to be a ground at least and one to have infinite resistance to ground.

Hmmmm?

 

[8Mud]

You just had to go and MUDdy up the water, LOL. Well some folks here love mud from what I hear.:roflmao:

It also says nothing about setting the TCU-TPS voltages or using percentages on the TPS using the square TCU to TPS connector.

But I have read here and elsewhere ( I forget where exactly) about the percentage setting procedure you and some others are using and I have read where some use the TPS-TCU connector for setting the percentage volatges.

I have just never tried it. Do you have any idea where the percentage method and the TCU-TPS settings originated????

In the FI section of the 88 FSM there is a procedure for setting the TPS. That actually confuses the heck out of me. In a perfect world with a 5.0 volt input to the TPS. the ECU side should read .8 volts M/T and TCU side 4.2 volts A/T. I'm not going to go into which pins are which.
All data recommends (I think) 82% of the input voltage for the TPS A/T. I've read both 82% and 83% in various places. And I've read both .8 and .82 volts for the M/T in various places.
I've never seen a Renix with 5.0 volt input voltage, it's usually somewhere between 4.6 and 4.8.
Sorry if I confused anybody, the more I think about it the harder it gets to understand.
Some of the confusion is trying to decide whether to set the TPS at ideal voltages designed for a 5.0 volt input or as a ratio.
.84 (84%) X 5.0 volts = 4.2..... .16 (16%) X 5.0 = 0.8.... 84% + 16% = 100% (interesting but irrelevant). The input voltage is rarely (if ever) 5.0 volts. The closer you set one side of the TPS to the ideal index voltage (of 4.2 volts for the A/T) the lower the other side gets ( away from the ideal 0.8 volts for the ECU).
Manual tranny is much easier, you only have one voltage to contend with, 0.8-.82 volts, the ideal setting.
IMO there is no ideal number in a practical sense. It's a conundrum, with no perfect definitive answer. Most people seem to agree that the TPS, TCU, A/T setting is the more critical of the two.
The start of the thread was high idle, the ECU side of the TPS being way out, can cause a higher than normal idle, as can a faulty TPS. And bad grounds, or high resistance in the wiring etc.

 

[8Mud]

Well I just collected some data on my power on, engine off,TCU-TPS square connection all at Idle:

A-B = .29 V
A-D = 4.36 V
B-D = 4.65 V

A-ground = 5.45 V
B-Ground = 5.16 V
D-ground = 0.80 V
---------------------------
Power off ohm readings:

A-Gorund = 550 ohms
B-ground = 1550 ohms
D-ground = 1355 ohms

A-B = 1025 ohms
A-D = 1074 ohms
B-D = 1963 ohms

I need an extra pair of hands or tool to run the tests at WOT. Maybe do that later. I was surprised to see all these resistance readings with the power off. I expected one to be a ground at least and one to have infinite resistance to ground.

Hmmmm?

I'm fairly certain you test with the key in the run position and the motor off.
The chassis to ground readings are kind of irrelevant, though some people have grounded the TPS, TCU ground circuit to chassis ground in the past.
Your A to D voltage looks a little high, late shifts?

 

[Ecomike]

I'm fairly certain you test with the key in the run position and the motor off.
The chassis to ground readings are kind of irrelevant, though some people have grounded the TPS, TCU ground circuit to chassis ground in the past.
Your A to D voltage looks a little high, late shifts?

I find that at this stage of the game no data is truely irrelevant. Better to have too much data as it sometimes gives a clue as to what is really going on, how to how the beast really works or what is really wrong. I posted it for possble future reference by me and others for now. Just being thourough, habit comes from doing research work.

Anyway, Yes all the published test procedures are power on, engine off, but you can not measure ground resistance and signal wires that should not be grounded but maybe have bad insulation somewhere that is partly leaking voltage to ground with the power on. That is why I took all the extra readings.

I am not sure what you mean by chassis to ground, do you mean ECU/TCU sensor ground to car body chassis ground? In mine case I am pretty sure mine is currently well under 0.5 ohms. Which is why I am surprised at all the high readings I see on the TCU/TPS side. I expected one of them to be less than 1 ohm.

 

[Ecomike]

Well I dug out all my old notes and print outs of how to's on this topic and Pin D is suppose to be ground, with less than 1 ohm to ground! I would say that 1550 ohms is just a little shy of that mark, yes? :shocked:

Well I did some further testing, I had the Pin A to D and Pin B to D volatges backwards. A to D 4.65 and B to D was 4.36 volts. I ran a new ground wire from the sensor harness, Pin D to the battery negative post. I have a good ground now, Pin D to ground reads about 0.7 ohms now from the sensor side of the connector and about 0.1 ohms from the other side. With the power on Pin D to ground reads 0.01 volts! Much better!

Interestingly Pin A to B still reads 0.29 V, Pin A to D still reads 4.65 V, Pin B to D still reads 4.36 V, but Pin A to ground now reads 4.67 V, Pin B to ground now reads 4.38 V and Pin D to ground reads 0.01 V.

I gave it a test drive and I think I see and feel some differences, but I have read that the TCUs go through a relearn procedure so I will take a few short trips including the highway and report back in few days as to what final differences it has made in the transmission operation. I definately noticed later shifts at WOT since adding the new ground wire to the TCU side of the TPS!:sunshine: It was still shifting too soon before this ground repair, like around 2000 rpm, it got up to nearly 3000 rpm in second this time before shifting to third at WOT.

One would think that after all the preaching I have done lately about good grounds, that I would have all good grounds on mine by now.:laugh: You Think?

 

[8Mud]

Well I dug out all my old notes and print outs of how to's on this topic and Pin D is suppose to be ground, with less than 1 ohm to ground! I would say that 1550 ohms is just a little shy of that mark, yes? :shocked:

Well I did some further testing, I had the Pin A to D and Pin B to D volatges backwards. A to D 4.65 and B to D was 4.36 volts. I ran a new ground wire from the sensor harness, Pin D to the battery negative post. I have a good ground now, Pin D to ground reads about 0.7 ohms now from the sensor side of the connector and about 0.1 ohms from the other side. With the power on Pin D to ground reads 0.01 volts! Much better!

Interestingly Pin A to B still reads 0.29 V, Pin A to D still reads 4.65 V, Pin B to D still reads 4.36 V, but Pin A to ground now reads 4.67 V, Pin B to ground now reads 4.38 V and Pin D to ground reads 0.01 V.

I gave it a test drive and I think I see and feel some differences, but I have read that the TCUs go through a relearn procedure so I will take a few short trips including the highway and report back in few days as to what final differences it has made in the transmission operation. I definately noticed later shifts at WOT since adding the new ground wire to the TCU side of the TPS!:sunshine: It was still shifting too soon before this ground repair, like around 2000 rpm, it got up to nearly 3000 rpm in second this time before shifting to third at WOT.

One would think that after all the preaching I have done lately about good grounds, that I would have all good grounds on mine by now.:laugh: You Think?

I've been through about everything you've been through numerous times. Trying to figure out where the choke points are in the ground circuit and where the resistance is in the power in and reference signal voltages.
There is a built in resistance in the TCU and the ECU. The ground circuit goes from the TPS back to the module and then to ground at the dipstick. The modules (both TCU and ECU) have a built in resistance in the ground circuit). I've tested four, the resistance is fairly constant in the TCU and ECU, leading me to believe it is supposed to be there. My guess would be some sort of surge protection, maybe a simple capacitor. I picture a ladder circuit with a capacitor in the ground leg, though I may be wrong.
I've been hesitant to ground the TPS ground circuit to chassis or battery negative ground. For the simple reason, the resistance in the module (ground circuit) may be a necessary part of the electronics package.
I gave up trying to identify the pin numbers long ago (bad eyes) There is only three wires black blue and gray (depending on which side of the connector your looking at). Black is ground, the other two are either the input voltage or the output voltage.

This setup makes testing and adjustment much quicker and easier, though the connectors may rub the hood insulation some. This way only takes two hands.

 

[Ecomike]

When I fixed the ground near the dip stick my ECU to TSP connector ground (ie the ECU ground) it read less than 1 ohm, most of which is from a very old tired TSP to ECU wiring harness connector (based on testing both sides of the connector). So I have never seen any internal ECU ground resistance!

I made three short trips so far, more testing planned since adding a new direct ground to the TCU-TSP ground wire.

Unless I am mistaken ( I thought I was wrong once, but it turned out I was wrong, LOL!), that TSP to TCU square connector in the photo you just posted is connected 180 degrees off, back wards, flip flopped 180 degrees. I base that on the fact that two of the wires, one on each side are not connected to anything the way it is connected in that picture! It may just be the angle of the photo, but it looks like there is no wire A on the left side???? Actually the more I look at it the connectors look to be attached correctly, but wire A on the left side looks to be in slot C?

I've been through about everything you've been through numerous times. Trying to figure out where the choke points are in the ground circuit and where the resistance is in the power in and reference signal voltages.
There is a built in resistance in the TCU and the ECU. The ground circuit goes from the TPS back to the module and then to ground at the dipstick. The modules (both TCU and ECU) have a built in resistance in the ground circuit). I've tested four, the resistance is fairly constant in the TCU and ECU, leading me to believe it is supposed to be there. My guess would be some sort of surge protection, maybe a simple capacitor. I picture a ladder circuit with a capacitor in the ground leg, though I may be wrong.
I've been hesitant to ground the TPS ground circuit to chassis or battery negative ground. For the simple reason, the resistance in the module (ground circuit) may be a necessary part of the electronics package.
I gave up trying to identify the pin numbers long ago (bad eyes) There is only three wires black blue and gray (depending on which side of the connector your looking at). Black is ground, the other two are either the input voltage or the output voltage.

This setup makes testing and adjustment much quicker and easier, though the connectors may rub the hood insulation some. This way only takes two hands.

 

[8Mud]

When I fixed the ground near the dip stick my ECU to TSP connector ground (ie the ECU ground) it read less than 1 ohm, most of which is from a very old tired TSP to ECU wiring harness connector (based on testing both sides of the connector). So I have never seen any internal ECU ground resistance!

I made three short trips so far, more testing planned since adding a new direct ground to the TCU-TSP ground wire.

Unless I am mistaken ( I thought I was wrong once, but it turned out I was wrong, LOL!), that TSP to TCU square connector in the photo you just posted is connected 180 degrees off, back wards, flip flopped 180 degrees. I base that on the fact that two of the wires, one on each side are not connected to anything the way it is connected in that picture! It may just be the angle of the photo, but it looks like there is no wire A on the left side???? Actually the more I look at it the connectors look to be attached correctly, but wire A on the left side looks to be in slot C?

Got it! Thanx for bouncing some ideas around with me. You were right the resistance I was testing in the ECU was in the connectors.
The major problem was the sensor circuit shared ground splice under the harness plastic sheath, maybe 8 inches on the sensor side of the C101 connector. Three sensor wires, TPS, Engine temp. to ECU ground and another I haven't idenitified. Go to one ground wire through the C101 and then to the ECU. Long story short, somebody did a poor job of crimping the squeez connector. I had between 4.5 and 61 ohms of resistance depending on how I twisted the harness.
Thanx again even the small successes make you feel good.

The TPS, TCU connector wires are OK, just in a knot on the far side of the connector.

Take your TCU out and check the resistance between the D-3 (TPS grd in) and D-7 (TCU grd out) pins. Sure acts like a condenser when I tested it. Somebody once told me a condenser was unlikely, more likely a capacitor in the ground circuit. MY XJ shifts well going up and down shifts. My schematic says the C-5 pin is also some sort of ground, but I had no success testing for a through ground, it's likely the ground leg of some sort of circuitry.
Both the TCU on my XJ and my spare test the same.

Your right there is no resistance in the TPS to ECU ground circuit, that was just in my harness. Fooled me because both the TCU and ECU ground circuit had about the same resistance */- allowing for line loss and less than perfect connections. Assumptions will bite you in the rear most every time.

 

[Ecomike]

Well I have been running tests on the TCU and TCU side of my TPS (my TPS is not very old) and have found some intersting values, & problems. But first here is the link to the pin outs and proper volatges for testing the Transmission Control Unit (TCU) for an AW4 TCU and the TCU side of the throttle Position Sensor (TPS).

http://www.transonline.com/transDigest/magazines/1997-10/Shift Pointers/index.html

There are 4 pages, be sure to read and print pages 1,3 & 4! This is one to be sure and bookmark!

Now on to the nasty discoveries I just made.

Everything checked out as normal except the following:

C10 read 0.5 to 2.0 volts with the brake OFF???? WTF??? and 11 Volts with brake applied which seems OK based on other battery voltage readings I got. Seems there is a small battery voltage drop between the battery and the dash area components, may be poor contacts along the way including the fuse box.....etc.

D1 was OK with 4.66 Volts and
D2 read OK at idle with 4.37 volts, BUT this is not .82 of 4.66 Volts (.82*4.66=3.82), so it seems high????

D2 read 3.78 volts at WOT. OMG! It should be like 0.5 volts apx! Some say it should 0.2 to 0.5 volts! I don't even have 10,000 miles on this TPS yet, and it has never been abused! I went and checked the reading at the TPS itself and sure enough it is way off on the range it should be giving me for the TCU side of the TPS. I tested it right across the sensor so it was not any wiring cross connects giving me the extra voltage. I Paid a god awful apx $75 for this two bit variable resistor thingy at Autozone less than 2 years ago! And I am begining to suspect it was bad when I bought it.

So I rechecked the ECU side of the TPS, and the ECU side of it looks better! It reads 0.80 volts at Idle and 3.24 Volts at WOT (which seems a little low to me?????) so maybe that is why it feels like I have 4 banger instead of 4.0 engine???? I need to recheck but I think my ECU input is about 4.7 volts. What should WOT of the ECU side of the TPS be?????

OK, other stuff, back to the TCU , I had <1.0 ohm at D7, and D3 grounds! This is good.

11.93 volts at D16 (a little low as my battery is about 12.5 to 12.9 Volts? but OK for now)

C-8, C-9, C11, C-14, C-15, C-16 all tested near perfect.

Note that unless otherwsie stated the readings are taken with the TCu connected to the wiring harness, but there a few tests listed where they tell you to power down the ignition and to disconnect the TCU from the harness and test from the harness connector pins directly, C-14 is an example!

Now the last big mystery is D-14. D-14 is suppose to have Battery volatge all the time! Only reason I can think for this is to keep volatile program memory alive!!!!!! Mine read 0.038 to 0.92 Volts with the power on and 0.01 Volts with power off! Definately a problem, but sure just how critical it is to fixing my problems.

Speaking of which I have had a lack of downshift (non-existant drop down on heavy acceleration), plus I still seem to be missing about 5 mpg of gas mileage which I suspect is related to these problems I have just finally located (only took 2 years of part time trouble shooting), and they may be affecting Torgue converter lock up.

I have been delayed working on this twice today already,
rain delays! Hasta

Lastly I find it quite puzzling that fixing the ground problem at the TPS (TCU side) yesterday did not leave a ground problem at the TCU itself????? Hmmm?

 

[langer1]

My Renix, 87 FSM does not list a different TPS voltage setting for Manual transmissions,

It should, they operate exactly in reverse. The % are also slightly different.

 

[langer1]

You got a bad ground or I should say the 5 volt ground. Which comes from the ECU.

 

[Ecomike]

You got a bad ground or I should say the 5 volt ground. Which comes from the ECU.

??????:dunno:

 

[Ecomike]

My Renix, 87 FSM does not list a different TPS voltage setting for Manual transmissions,

It should, they operate exactly in reverse. The % are also slightly different.

So what settings and % are you using on yours?

 

[8Mud]

Well I have been running tests on the TCU and TCU side of my TPS (my TPS is not very old) and have found some intersting values, & problems. But first here is the link to the pin outs and proper volatges for testing the Transmission Control Unit (TCU) for an AW4 TCU and the TCU side of the throttle Position Sensor (TPS).

http://www.transonline.com/transDigest/magazines/1997-10/Shift Pointers/index.html

There are 4 pages, be sure to read and print pages 1,3 & 4! This is one to be sure and bookmark!

Now on to the nasty discoveries I just made.

Everything checked out as normal except the following:

C10 read 0.5 to 2.0 volts with the brake OFF???? WTF??? and 11 Volts with brake applied which seems OK based on other battery voltage readings I got. Seems there is a small battery voltage drop between the battery and the dash area components, may be poor contacts along the way including the fuse box.....etc.

D1 was OK with 4.66 Volts and
D2 read OK at idle with 4.37 volts, BUT this is not .82 of 4.66 Volts (.82*4.66=3.82), so it seems high????

D2 read 3.78 volts at WOT. OMG! It should be like 0.5 volts apx! Some say it should 0.2 to 0.5 volts! I don't even have 10,000 miles on this TPS yet, and it has never been abused! I went and checked the reading at the TPS itself and sure enough it is way off on the range it should be giving me for the TCU side of the TPS. I tested it right across the sensor so it was not any wiring cross connects giving me the extra voltage. I Paid a god awful apx $75 for this two bit variable resistor thingy at Autozone less than 2 years ago! And I am begining to suspect it was bad when I bought it.

So I rechecked the ECU side of the TPS, and the ECU side of it looks better! It reads 0.80 volts at Idle and 3.24 Volts at WOT (which seems a little low to me?????) so maybe that is why it feels like I have 4 banger instead of 4.0 engine???? I need to recheck but I think my ECU input is about 4.7 volts. What should WOT of the ECU side of the TPS be?????

OK, other stuff, back to the TCU , I had <1.0 ohm at D7, and D3 grounds! This is good.

11.93 volts at D16 (a little low as my battery is about 12.5 to 12.9 Volts? but OK for now)

C-8, C-9, C11, C-14, C-15, C-16 all tested near perfect.

Note that unless otherwsie stated the readings are taken with the TCu connected to the wiring harness, but there a few tests listed where they tell you to power down the ignition and to disconnect the TCU from the harness and test from the harness connector pins directly, C-14 is an example!

Now the last big mystery is D-14. D-14 is suppose to have Battery volatge all the time! Only reason I can think for this is to keep volatile program memory alive!!!!!! Mine read 0.038 to 0.92 Volts with the power on and 0.01 Volts with power off! Definately a problem, but sure just how critical it is to fixing my problems.

Speaking of which I have had a lack of downshift (non-existant drop down on heavy acceleration), plus I still seem to be missing about 5 mpg of gas mileage which I suspect is related to these problems I have just finally located (only took 2 years of part time trouble shooting), and they may be affecting Torgue converter lock up.

I have been delayed working on this twice today already,
rain delays! Hasta

Lastly I find it quite puzzling that fixing the ground problem at the TPS (TCU side) yesterday did not leave a ground problem at the TCU itself????? Hmmm?

D-14 comes from a fusible link, through a connector, through a splice, to the D-14 pin (red) at the TCU. The splice splits the constant power to the ECU also. So if you have no power on the D-14, you likely also have no power to the ECU constant power B-7 (red).
The ECU half of my TPS is 7.5 volts and and 4.45 at WOT.
The TCU half of my TPS is set at 3.8 volts, I have 4.65 volts in X .82 (82%)= 3.8 volts. Though I have noticed, it has better shifts at around 4.0 volts (though this setting did cost me some gas mileage). It is .16 volts at WOT. This TPS is actually an original from 87, don't underrate junk yard parts. New isn't necessarily better, sometimes a tried and proven part is the better choice.
I tend to make one change at a time and drive it for awhile, before making anymore changes.

 

[Ecomike]

D-14 comes from a fusible link, through a connector, through a splice, to the D-14 pin (red) at the TCU. The splice splits the constant power to the ECU also. So if you have no power on the D-14, you likely also have no power to the ECU constant power B-7 (red).
The ECU half of my TPS is 7.5 volts and and 4.45 at WOT.
The TCU half of my TPS is set at 3.8 volts, I have 4.65 volts in X .82 (82%)= 3.8 volts. Though I have noticed, it has better shifts at around 4.0 volts (though this setting did cost me some gas mileage). It is .16 volts at WOT. This TPS is actually an original from 87, don't underrate junk yard parts. New isn't necessarily better, sometimes a tried and proven part is the better choice.
I tend to make one change at a time and drive it for awhile, before making anymore changes.

7.5 Volts!:gag: How the hell are you getting that at the ECU/TPS input? The books all says 5 volts input!??????

Checking my records I am starting to think my TPS is a junk yard part, but its been over 1 year now and my older records are not as good as I am keeping now. I started keeping meticulous records about 9 months ago so I could go back and see what I did when, and what effect it had. These beasts are just too complicated to depend on memory after a while.

Where does that fuse link start at?

I am sure my ECU is working, but if that B-7 is for maintaining ECU memory only, with the key off, like the TCU (I am guessing that line D-14 is power for the memory) that may be possible. I wonder if a prior owner decided to disable the memory on both????

Can you tell me any more about tracing those lines and the splice for B-7 and D-14 and for the fuse link location?????

I was shocking (shopping, LOL) for a TPS late yesterday, and found at least 5 different manufacturers brands with prices running all the way from $59 to $150 for two connector 87-90, auto transmission TPS, including Borg warner, Wells, Airtex, AC Delco, and Standard.

The best deal I found was $34.95 for an OEM TPS from Teamgrandwagoneer.com (I think it is www.teamcherokee.com that I started at).
arty:

I am still puzzled about that residual volatge shpwing up on the brake line "C10 read 0.5 to 2.0 volts with the brake OFF", which should be reading zero volts!

I am starting to wonder if I don't multiple wiring harness issues that I was previously unaware off.