Jeep transmission issue

336wheeler

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Joined
Sep 9, 2006
Location
Boone
So I finally figured out why my freaking Jeep isn't wanting to fire. I pulled the tranny out to make sure I had put the correct flexplate in it - I had. I put my crank position sensor into the bellhousing to make sure the depth to the flexplate was good. The problem - the torque converter doesn't sit far enough back in the transmission casing for the CPS to read the discontinous "squares" in the ring around the flexplate, so in turn it's not getting any blipping action going on to do anything. Can anybody think of a reason why my torque converter won't go far enough back for the flexplate to sit so that the CPS will read the squares? It's 27 spline, non lock-up. It may have rebuilt, I'm not sure. It's in a TF999... I have a new TC on the way, but if nothing is wrong with the one I have then the new TC will sit in the same position. Any thoughts?
 
The TC doesn't effect the position of the flexplate. The flexplate is bolted to the engine and then the CPS sends what it reads to the PCM.
If you're 100% sure you're not getting spark because of the CPS, I would look at the CPS and then make sure where the CPS sits in the bellhousing is in good condition. Also check the ASD relay.
Chris
 
Hmm yeah, you're right... which leaves the fact of the matter being that the CPS still doesn't line up with the squares in the flexplate. Are there wider ringed flexplates made? I have a part # 5300 6328 (iirc), and this just doesn't reach back far enough to the CPS. The way I checked it was that I had the TC in the tranny, bolted the flexplate up to the TC, and put the CPS in the bellhousing of the tranny to see where it landed.... which not on the squares. Unless those sensors are able to read in a severe diagonal manner, I would have to assume that the CPS should be lined up on top of the holes?

A guy told me that I could check the CPS by putting a test light in the cam sensor (two wire plug, plugs into the coil), and watch for intermittent blips. He said that if I had blips, the CPS was right... if I didn't, then I wasn't getting fire from it.
 
Are you sure you had the TC in all the way, sometimes its tough to get it all the way in, you should here 2 full click thuds as it slides in............. push turn thud........push turn thud. with tranny installed, flexplate bolted to motor, TC should turn freely. Also automatic and manual crank sensors may be different one could slide in to bellhousing and project further back i would look at them both side by side. DON'T use a test light on electrical circuits escpecially when you don't understand them. That is the #1 RULE in electrical repair. Otherwise you can fry you computer by sending it a ground. Use a volt meter, you can check the signal at the computer w/ a voltmeter if you have it there you rule out wiring, sensor, flexplate all out. also what year flexplate are you using what year ECU are you using.
 
I'm using a '95 ECU (came factory with a manual), the flexplate is for a '94-'96 I believe, with an auto.
 
do these not have a seperate TCU like an AW4?

I am going through a swap right now which has a 88 engine, 88 TCU, 87-90 flexplate and cps and a 95 TC/trans,93 t-case.

I hope to fire it up tomorrow, but wil see if i have any issues similar to yours, i hope not
 
so the first thing you need is an auto CPS for a 94-96 and then you need to figure out if your 94 manual ECU can reconize that signal, I am thinking not
 
I have the auto CPS sensor that has the proper shape and depth for the TF999. The computer I am not sure of. How could I find that?
 
If your getting a signal from the CPS at the computer. then chances are the The Ecu is not interpreting it or you have another problem totally unrelated.
 
No offense to anyone in this thread, but there is a lot of mis-information and lack there of.

Is this not a factory drivetrain?

I have never found a difference in an auto's CPS or a manual CPS as long as the years are the same. The AW4 (1994 XJ donor) in my CJ has the same CPS as a same year YJ manual and auto. The CPS in my 1999 TJ, that was factory equipped with an AX15, was exactly the same as the one left over from the 2001 XJ AW4 I swapped in it.

There are differences in the CPS as you go from OBDI-OBDII but this doesn't seem to be an issue in your case. I would check to make sure you don't have an AW4 flexplate as it is NOT the same as the TF999 flexplate.

The automatic shut-down relay is what allows the coil to become energized. If the ASD does not get a signal from the ECU (that processes the info from the CPS) then the ASD will not energize the coil, hence, no spark.

Chris
 
Where is the ASD and can I test it? The TF999 is one from a TJ. The harness end from my old CPS was correct, the sensor end was not, so I cut and crimped both. Jpdudejr, do you know the part # needed?
 
no misinfo was given, just basic diagnostics, in order for it all to work the parts have to be corect I made no suggestion of what was or was not correct merely stated you need corresponding parts once you have those, then check the signal at the computer. has the signal been checked yet, NO, I bet the ASD relay is fine since the motor ran proir to auto swap, but thats just me. You can waste your time checking the relay, but i might start where you started messing with stuff, and since he said he cut the wires b/c plug was different, me thinks the CPS's are different.
 
Anybody see a problem with crimping the right harness end with the right sensor end? Otherwise it would need a new wiring harness, correct?
 
I just broke down and ordered the 4.0L CPS relocation kit from Advance Adapters that reads off of the harmonic balancer so that I can quit messing with this shit.
 
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