98 XJ P0700 and P0705

[Griffin]

I have truly given this issue my all, so I yet again turn to the knowledgeable enthusiasts here at .

About 3 years ago, my automatic 98 Cherokee Classic would not start one day. Problem wound up being the neutral safety switch. Unfortunately, the switch wound up freeing itself from the transmission in a destructive way so rebuilding was not an option.

Since then, I have had 5 of these switches on my vehicle.
1. Ebay special - worked for a week, then vehicle no longer started.
2. Warrantied Ebay special - actually worked for two years or so.
3. Came from Amazon - worked for 6 months, no longer shifts into 4th.
4. A different one from Amazon - defective out the box, returned.
5. Came from boneyard - Mopar unit, rebuilt by me. No 4th gear.

Here is what I have tried (besides replacing or rebuilding the NSS):
- fuse #10 has been replaced with no difference
- all grounds have been cleaned multiple times
- I have cleaned the NSS connector itself
- I have reset the ECU several times
- switch has been adjusted by loosening small bolt, marking threshold for reverse lights, and going smack dab in the middle of that

Here is what I know:
- if it's over 60-70 degrees out, there is a good chance it will shift into 4th gear if I clear the codes. It will stay in 4th with no CEL. I don't know if this is related to the issue or not.
- it starts every time in park, needs jiggling in neutral
- if put the vehicle in the run position, clear the codes, start it, and hit 45 mph, it will shift into 4th. However, it will kick itself out of overdrive and turn the CEL back on 10-15 seconds afterward.

I know the code P0700 is just a generic code that says something is wrong in the transmission control system. The P0705 states "Transmission Range Sensor Circuit Malfunction (PRNDL Input)" on my cheapie bluetooth OBD II reader. I'm starting to wonder if some wire somewhere is shorting out and it's just hidden by split loom. Before I start tearing into everything, I was hoping for some input. My last resort is currently the $350 Mopar NSS lurking in my browser, and I'm really hoping it doesn't come to that.

 

[RCP Phx]

The 700 code means that the ECU and TCU are not communicating.

 

[Griffin]

Does TCU signal pass through the NSS? I assume it does.

 

[kastein]

It does really sound like the nss or possibly the wire for the OD position sense from the nss to the TCU. I would measure things before spending money on parts though. Possibly adjust the nss very slightly, as the TCU may be seeing the OD signal dropping out and (possibly) the 3 signal coming on, leading it to downshift thinking it is now in the 3 position and not allowed to use OD.

 

[RCP Phx]

Does TCU signal pass through the NSS? I assume it does.

I believe it to be the other way around.

 

[Griffin]

I will tinker with it tomorrow. Thanks folks.

 

[lawsoncl]

By 4th gear, you do mean the actual gear and not the torque converter lockup, right? Backprobe the pins at the TCU and verify that it's getting the right voltages on the pins as you move the shifter. Check that the TPS voltage and brake pedal pins look right as they could prevent upshifting and t/c lockup. Wouldn't hurt to checl the solenoid resistances to ground while you're there too.

 

[Unclewolverine]

Definitely check the tps. Those things make make the transmission shift all sorts of wonky; and are susceptible acting differently at different heat and humidity levels.

 

[Griffin]

By 4th gear, you do mean the actual gear and not the torque converter lockup, right? Backprobe the pins at the TCU and verify that it's getting the right voltages on the pins as you move the shifter. Check that the TPS voltage and brake pedal pins look right as they could prevent upshifting and t/c lockup. Wouldn't hurt to checl the solenoid resistances to ground while you're there too.

That is correct, I am talking about the actual gear. The torque converter still locks up but refuses to shift into 4th gear. What pins should I check for the shifter and what voltages should they have?

I checked the TPS sensor a while back when I was troubleshooting and everything on it checked out. I can't remember the specific voltages but they were in the correct range. Same deal with the solenoids.

 

[lawsoncl]

Pin 21 should have voltage with the shifter in (1-2)
Pin 9 should have voltage in (3)
Pin 22 should have voltage in (D)
Pin 23 is the brake switch . I don't remember which way it changes.
Pin 17 is the TPS signal

Have you verified the throttle-body to trans cable is adjusted correctly a well? Usually that cause mushy or not shifting, versus not getting to 4th.

4th Gear both solenoids are off
3rd Gear just solenoid B is on
2nd Gear is both solenoids on
1st Gear just solenoid A is on

 

[Griffin]

Thank you for the response lawsoncl. I did some digging earlier and found these diagrams, one similar to yours. Just going to dump them here just in case somebody else needs them.

I followed the "Testing TCM Systems" procedure exactly and everything checks out, including the TPS. As for testing the NSS at the connector, everything seemed to work fine, except neutral - which requires a little jiggling. I tried adjusting the switch again but I am going to need to get another person to help me like I did last time.

The kickdown cable is adjusted properly.

 

[Griffin]

Looks like my diagrams didn't go through... Try this again!

 

[boncrshr]

I just got rid of my P0705 code and it was kind of strange how it happened. I changed the switch and everything functioned like it should..back up lights, only started in Park and Neutral, etc. However, when I did the continuity test on the NSS switch pigtail, the multimeter showed no continuity despite everything functioning, so I adjusted the switch at the transmission until there was continuity in neutral, which was a very slight amount, maybe 1/16" or so. And the P0705 code did not return.

 

[boncrshr]

*multimeter showed no continuity in neutral*

 

[gradon]

You’d think it wouldn’t start in N if the pigtail didn’t have continuity. I’m chasing a p0705 on the lady’s ‘00 and am about to do continuity check on the tcu harness.


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[boncrshr]

You’d think it wouldn’t start in N if the pigtail didn’t have continuity. I’m chasing a p0705 on the lady’s ‘00 and am about to do continuity check on the tcu harness.

I thought so too and that's one reason it took me so long to fix it. I figured if everything was functioning properly, then the NSS was adjusted correctly, but not in my case.

 

[Griffin]

I tried adjusting the switch just a hair while somebody ran through the shifter and verified it started in P and N with reverse lights in R but I am not sure if it did anything. N is still a bit finicky. For better or for worse, it's warm outside (over 60F/15C) and 4th gear has returned. Cleared the codes and everything works perfectly fine.

I hate intermittent issues.

 

[gradon]

I went through and did the continuity checks on each gear. At first P, R, and N were .3 ohms, 3 was 1.2, and 1-2 were 1.8 the first time and then 4 when i was lazy with the shifter. I adjusted it two times to get them all down to .3 ohms. The P0705 came back.


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[boncrshr]

I went through and did the continuity checks on each gear. At first P, R, and N were .3 ohms, 3 was 1.2, and 1-2 were 1.8 the first time and then 4 when i was lazy with the shifter. I adjusted it two times to get them all down to .3 ohms. The P0705 came back.


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Oh no...I wonder if it could be your TCM? It seems like you have eliminated everything else.

 

[Griffin]

I am here to admit defeat once again lol. I hate to say it, but I've been living with the no overdrive thing for a while now. I hate intermittent garbage.

However, I do have some new developments! I have tested pins 9, 21, and 22 at the TCM harness connector once again. Here are the resistance values using the ground at pin 24. I was not able to find anything in my fsm about what the values should be, so I am hoping somebody here can provide reference or can find a source for what these values should be.

pin 9 - 15.2 ohms
pin 21- 16.7 ohms
pin 22 - 15.3 ohms but hops around for half a second at random, have seen it spike to 30 ohms very briefly.

I did test pin 23 as well for the brake switch. I think the circuit was broken when I hit the brake pedal if I remember right and closed once I let off.

I think there is a short for the wire that connects to pin 22 somewhere. I want to back probe the lime green + black wire that comes off of it and then the black wire for ground. Then I'll go for a drive and see if potholes cause the resistance to jump around. If it does, it could be shorting out somewhere right?

Just a heads up: I am very new to wiring and pick up what I can when I'm not schooling or working, so bear with me. Just going off what I can gather from youtube and other sites.