99 XJ DD & Weekend Warrior

So after the last couple wheeling trips, my muffler received some carnage and now has more holes and gashes in it than a Las Vegas bunny ranch. :eyes:
I've been doing some research, and asking other peoples opinions, and I finally figured what I'm gonna do for a replacement.


Best price I could find LOCALLY, (that had same day pick up available) was my local NAPA Store.
At just under $40, I dont think I could go wrong.


So Saturday I get up and go into the garage to start the Jeep and.......
No fire.
:confused:It cranks but wont start. Awesome. :thumbup:
I spend the rest of the day and into the evening troubleshooting everything I can...
From going thru the voltage and resistance testing procedures of various sensors and components...
To actual removal and inspection of said sensors and components.
Thru my investigation I see this:
(easy to overlook when most of what yur doing is under the hood or under the jeep)


So after a slurry of curse words that I'm sure offended the entire neighborhood, I go online and start digging around to find an answer,
most are telling me it's just the instrument cluster, some are telling me its the PCM.
I try to hook up a code reader to find out more information.....
(hows about some "NOPE" to go along with that fail....)


So as some of you may know Icemans is parting out his late model,
I hit him up for the tranny cooler he's been saving for me, and ask if he's still got the PCM...
Sure enough, he does!...and both were acquired for a fair price.
(old and new-to-me)


The PCM was swapped out and low and behold......
 
Well at that point all I wanted to do was end this misery... :explosion


So i did what any sane, level headed, law abiding citizen would do in a situation like this....
I tore the dash apart:


This was of course to get at the instrument cluster and not out of sheer frustration.
I took it inside (once out of the jeep) and proceeded to clean the contacts, using a small file.


After a good scouring on the leads (which SEEMED to be fairly clean/clear of corrosion/debris/oxidation to begin with)
....I took the instrument cluster back out to he Jeep and installed it.
"no bus"
:thumbup:
:flamemad:

So at this point I was about ready to set the damn thing on fire.
I had up to this point:
-tested the TPS
-tested the Crank Position Sensor (CPS)
-tested the ASD relay
-tested the fuel pump relay
-bypassed the fuel pump relay
-bypassed the ASD relay
>>> neither of these options worked other than I DID manage to get the fuel pump to turn on <<<
-tested the CKS (CAM position Sensor / aka pick up coil / aka Distributor Ignition Pickup / aka stator / aka distributor switch plate)
-checked every fuse in the jeep (three times) - using a logic probe
-swapped the CPS for a new one (I had two spares)
-swapped the coolant temperature sending unit. (had one already)
-tried to pull codes - unsuccessfully
-reset the computer (twice)
-cleaned contacts on back of inst. cluster
-blew out female connectors in dash where inst. cluster plugs in.
-swapped relays where I could
-cussed a LOT
-bled a little
-drank more than I should
-did countless hours of research online and thru my FSM (Factory Service Manual)

So thats where I'm at.... A no starting - no bus showing -bout to go to the shredder Jeep Cherokee in my garage that is starting to get on my last nerve.
.... more to come - stay tuned
 
(Some good info posted from a jeeps unlimited site, easy troubleshooting!) hope it helps

There are 2 kinds of NO BUS issues:

1. You see NO BUS but the engine runs fine (this is a dash issue and disconnecting, cleaning, using dielectric grease and reconnecting usually resolves)

2. You see NO BUS and the engine does NOT run. This is usually an engine management sensor shorting out and 99% of the time, it is the crankshaft position sensor. But it theoretically could be any of the 5 volt engine management sensors or even the computer itself. Best strategy here is to remove the suspects from the bus one at a time and see if that resolves it. For example, remove the connector from the crank sensor, then turn the key to the on position. If the NO BUS is gone with the crank sensor out of circuit, you have proof positive that the crank sensor is to blame.
 
90xjblue said:
(Some good info posted from a jeeps unlimited site, easy troubleshooting!) hope it helps

There are 2 kinds of NO BUS issues:

1. You see NO BUS but the engine runs fine (this is a dash issue and disconnecting, cleaning, using dielectric grease and reconnecting usually resolves)

2. You see NO BUS and the engine does NOT run. This is usually an engine management sensor shorting out and 99% of the time, it is the crankshaft position sensor. But it theoretically could be any of the 5 volt engine management sensors or even the computer itself. Best strategy here is to remove the suspects from the bus one at a time and see if that resolves it. For example, remove the connector from the crank sensor, then turn the key to the on position. If the NO BUS is gone with the crank sensor out of circuit, you have proof positive that the crank sensor is to blame.
Click to expand...
YUP, Did all that and then some.
Its a gremlin for sure, because even with the coolant temp sending unit, the CPS, the CKS, the TPS all disconnected, I still got the "no bus".... now the only senors I did not remove (unplug) from the system were the o2 sensors, I dont think that they would cause THIS.
And after a good cleaning of the male, and a blowing out of the female connectors in the dash, and STILL having the issue .....until i did some stuff under the hood which made no sense (see the video below) .... makes me think there is other issues I need to track down.
 
99 XJ DD &amp; Weekend Warrior

First thing i would do is disconnect the o2 sensors one at a time and test fire the motor.I have seen them do very weird things when those get shorted. The second thing pull the pcm out and check through the engine harness and inspect it thoroughly. Any fluids/oils that have made there way in can me corrosive to the wire insulation and cause all sorts of issues. I had a buddy with a really nice 5.2 dakota. He had an oil leak that made its way into the harness and he ended up scrapping it because it was too far gone. Id pull the computer out and start testing the continuity at the pcm connectors. Also a word of caution. If there is a short you could have already fried your second pcm. Check all that stuff before you put the pcm back in.

Good luck man.
 
ItsAlive.jpg


So as you may have guessed, I HAVE FIXED THE PROBLEM!!!
After getting tons of good advice from XJTalk members, Jeepforum, and NAXJA alike, I was able to piece together a solution....
Oddly enough, the one component I was going to swap out shortly after I swapped in the donor transfer case was the culprit and cause of all these issues.
The VSS (Vehicle Speed Sensor) was to blame. Apparently it is in the same 5volt family of sensors as the Crank Position Sensor (CPS) ... o2 sensors.... and TPS (Throttle Position Sensor)...as well as all the others...
I HAD NO IDEA.
I figured, "why, during the startup sequence does the PCM need to check the condition of the VSS?" ...and "why would the SPEED of the vehicle have any bearing on the PCM to begin with"..... well i guess it does, and swapping out the VSS from the donor T-case for the one out of my old one solved my problem. One little sensor took down the entire system.
The VSS is located on the side of the transfer case, regardless of the year of XJ:
speedohealer-3.jpg

(picture courtesy of: www.stu-offroad.com)

It's very easily removed by a single bolt and a retaining clip.
231%20SYE%20(9).jpg

(picture courtesy of: www.4wdmechanix.com)

Pulling the VSS straight out removes it, this is not a serviceable part (for now - i may change that here very soon) ...so its just a matter of replacement.
The one I pulled out had an orange gear with the number "1" embossed on it,
and the one that came out of my old case was green, and had the number "4" embossed on it.


The stock one (green) is a 35 tooth, the one out of the donor case (orange) is a 36 tooth.
According to the info over at Morris 4x4 Center ...the orange one is for 33's and 4:10's.

With the two VSS units out of their respective t-cases, I merely switched the gears between the two (to keep my mental speedo-adjustment the same)
And installed the old one into the donor t-case.


Once done, I reset the computer, turned the key on and VOILA!
No more "no bus" ...all the gauges came to life, and the jeep fired right up.
(Also no more P700 code either.) WOOT!
 
SO.... what started this whole "no bus/ no start" adventure in the first place
was me (trying to) start the Jeep and take it to my local exhaust shop where I was going to have my old beat up,
...hole ridden Dynomax turbo muffler cut off and the new Thrush Glasspack welded on.....
I'm happy to report that the mission has been completed now! :thumbsup:

Over the last 5+ years that Dynomax has held up to an insane amount of abuse.
... but as with anything, it could only take so much.


The result?.... a muffler that passes, more than it muffles, which ordinarily might not be a bad thing...
But in this case, because of the shape and position of the holes, and the flappy pieces of metal over said holes....
The resulting tone from my exhaust was NOTHING short of a fart can in a blender.


The old Dynomax was cut out, the Thrush Glasspack was flanged, and welded in place....


Although I still have a header leak that is taking center stage right now, the results so far are staggering.
The tone is beautiful, and the change in back pressure has restored the torque curve to right where it needs to be.
Once I fix the header leak, I'm going to be super excited to hear what sort of sound the jeep is going to have when its all said and done.
Stay tuned!
 
Nice! I need to do the same thing! Lol my stock muffler is like Swiss cheese and the cat sounds like marbles in a coffee can!

Glad you got er up and running again!
 
Bronzewyrm said:
if that's your mission. hit the show going down at PIR. all the homeys will be there.

Bronze.
Click to expand...
It's the 3rd Annual No Roads Required Offroad Show...
It's down at The Portland Int'l Raceway, just off I-5...
The show goes from noon to 4pm - entry fee is $10
https://www.facebook.com/events/291222137697593/

I'll be there! (most likely hanging out at the R&P 4WD / Jeep Lid / Metal Cloak Booth.) Would be a great chance to come say hi, introduce yourself, and talk Jeep for a bit.
 
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