fb97xj1

Hello there. First time poster, need some help. Bought myself a completely stock and practically rust free 97 XJ (AW4/NP242) a couple months ago to give the Mustang a much needed break. It (the XJ) was all sunshine and rainbows up until two weeks ago when the rpms started acting funny. There was no CEL, but my first thought was TPS or IAC) so i bought an Actron code reader. The only codes given were a P0700 and a P1964, which seem to come up quite a bit from what i have read so far. Just yesterday the CEL came on. Scanner spit back a P1698, which is probably what triggered the P0700, so i checked the DLC voltages with and without the TCM connected and it would seem as tho the TCM is bad, or atleast suspect.


TCM connected with key on:
DLC 3 and 4 = 1.398 to 1.422
DLC 3 and 5 = 1.349 to 1.433
DLC 3 and 11 = 0.015 to 0.23
DLC 11 to ground = 11.92


TCM disconnected with key on:
DLC 3 and 4 = 2.358 (+/- 0.002)
DLC 3 and 5 = 2.358 (+/- 0.002)
DLC 3 and 11 = 0.016 to 0.020
DLC 11 to ground = 11.92


Ill check the ohms in the morning just to be thorough, but i already suspect the TCM as being the problem. Now, i have read that the 97 TCM was a one year deal and can be very hard to find. I checked mine and it is indeed a 56027951. Flipping fantastic. Is it possible to swap the TCM harness connector in the 97 to fit a 98 TCM, or is there more to it than that? This OBD2 stuff is still new to me so i am still learning whats connected to what.


Anything you guys and gals can add is greatly appreciated. Thanks.

fb97xj1

Update: ohms read 59.8 for 3 and 4 as well as 3 and 5 at the DLC.

CCKen

I don't think I understand how you were taking your readings.


TCM connected with key on:
DLC 3 and 4 = 1.398 to 1.422
DLC 3 and 5 = 1.349 to 1.433
DLC 3 and 11 = 0.015 to 0.23
DLC 11 to ground = 11.92


TCM disconnected with key on:
DLC 3 and 4 = 2.358 (+/- 0.002)
DLC 3 and 5 = 2.358 (+/- 0.002)
DLC 3 and 11 = 0.016 to 0.020
DLC 11 to ground = 11.92

Here's a chart you can work from:


You should be reading from pin cav 3 to 4 or 5 and 11 to 4 or 5 to look for the 2.5 volts. Key to RUN/ON, engine not running.


And for the resistance reading (battery disconnected, key to LOCK), from 3 to 11. 60 Ohms.


But by the looks of the 3 and 4 readings/3 and 5 readings, it would look like when the TCM is disconnected the voltage reading is within range.


I don't know what you are doing here: "ohms read 59.8 for 3 and 4 as well as 3 and 5 at the DLC."

fb97xj1

Sorry about that, yesterday was apparently "one of those days", and then some. Good lord! The voltages quoted in bold for 11 to ground should have read 16 and ground on my part, not 11. My mistake. And the values for 3 and 11 was me checking voltage for some reason. And the ohm test was done using 3 and 11. Hand me the dunce cap, and i will wear it with pride lol.


Corrected post:


TCM connected with key on/engine off:
cav 3 and 4 = 1.398 to 1.422v
cav 3 and 5 = 1.349 to 1.433v
cav 16 to ground = 11.92v

TCM disconnected with key on/engine off:
cav 3 and 4 = 2.358v (+/- 0.002)
cav 3 and 5 = 2.358v (+/- 0.002)
cav 16 to ground = 11.92v


Battery disconnected:
cav 3 and 11 = 58.9 ohms

CCKen

What were the voltages for 11 to 4/5?


Regardless, it looks like the TCM is dragging the CCD Bus down


58.9 Ohms is a tad off which makes me think the instrument cluster (or the CCD Bus wiring) is off a bit.. Normally you would see 60 Ohms dead nuts.


I wouldn't hesitate to replace the TCM based on your readings. - but that's me.


Here ya go... LOL

CCKen

BTW...Good luck finding a 1997 TCM. They are so rare they make hen's teeth look as common as roadside gravel.

fb97xj1

Thanks lol. Here is the rest of my test.


TCM connected with key on/engine off:
cav 11 to 4 = 1.289v
cav 11 to 5 = 1.260v


TCM disconnected with key on/engine off:
cav 11 to 4 = 2.30v
cav 11 to 5 = 2.30v


Youre not kidding on trying to find a 97 TCM. I called around to see if anyone might happen to have one or if they had any leads on who might. Nope. Looks like i need to take it to the stealership. Maybe i can fix it, who knows. Ever open one?

CCKen

Dealer won't work on it.


I've never opened one, even if I did I wouldn't know what to do. You may want to verify that pins and pin cavities 6 and 7 are free from corrosion.


You might try a '98+ TCM. The TCM connector pin outs for the '97 are the same as the '98+ except the '98+ has three circuits for the Input Speed Sensor and the Output Speed Sensor.


In '98 there was a AW4 design change that introduced an ISS and a different OSS. The '97 doesn't have these so the '98+ TCM internal diagnostics may be looking for these inputs but the '97 AW4 won't be giving them, which may trigger a DTC.


Why don't you see if you can get a '98+ TCM from the bone yard and see if it works - then let us know.


I think the '98+ TCM mount feet are different than the '97 so some adjustment will need to be made.


Here's the pin out:

fb97xj1

Thanks for the pinouts. I think those 3 pins are going to be a problem as it would seem as the 97 PCM was superceded by another part number in 98, according to ebay anyway. So i guess i am back to square one.



BTW, why wouldnt a dealer work on mine? I was just hoping to have them hook it up to a DRB and see what the TCM tells them.


















Anyone ever hear of, or deal with allcomputerresources? They sell refurb'd PCM and TCM for Jeeps. Thinking about giving them a shot.

CCKen

The part number was superseded in '98 because it manages a different version of the AW4, as explained above.

Work on it means open it up and 'work on it'.

If you leave it installed and take the Jeep to the dealer, they will put their DRB III tool on it but it may only show a code.

Get ready to pay $100 for nothing.

Do one of those online junk yard parts locator sites for a TCM, or check with that outfit you mentioned.

fb97xj1

Sorry to leave this in limbo for so long, which isnt cool, but other projects kept popping up. Mustang stuff.

My P0700 was the result of a dirty ground. G101 (near the dipstick) in particular was covered in oil (needs a valve cover gasket) that found its way between the block and into the threads, but it wasnt loose. So i hit it hard with electrical cleaner, pulled it apart, sanded/wirebrushed everything to clean metal and noticed an immediate improvement in shifting. And i did find another TCM, which has been working just fine for the last month. I will assume the old TCM was just fine so i will keep it as a spare. The only codes have been 12 and 55. Awesome.

CCKen

Thanks for the follow up, but I do have a question. When you say G101 (near the dipstick), what do you mean? G101 is at the coil mount studs.

fb97xj1

Well color me corrected, G102 was covered in oil. Must be one them days, been having quite a few lately. I was going by the FSM as it shows 2 locations for G101, in every illustration covering it. Assumed it was another Jeep thing. There is mention of G102 on the connector locations page that says "near engine connector C107", which i found, but as far as an illustration calling out G102 by name, nope, just an N/S (not shown). Jeep mustve given the proofreader off that day when the FSMs were sent off to print. Thanks alot, Jeep proofreader guy. I hope you run out of blinker fluid.

BlueRidgeMark

My usual local independent shop replaced my '97 just a few months ago. Then the replacement went bad and left me beside the road, so I had it towed to the dealership. They spent a few days making sure it was the TCM, and then replaced it. The first and second replacement were both obtained through CarQuest, and nobody mentioned there being anything difficult about getting one.