Hello all, newbie here, just picked up a 1998 XJ Sport two door, 4WD, 4.0L, with a manual transmission. Been trouble shooting CELs and error codes in an effort to get it inspected here in Texas. Have it down to the two codes below, and it seems like the PCM 'thinks' the vehicle has an automatic transmission, but in fact its a manual. The previous owner installed a re-mfgd PCM at some point, and I haven't been able to find much on the subject of different PCMs for auto vs manual, or re-programming, etc.

Error codes from Autozone (& text from factory service manual)
P1698: No CCD message from TCM (No Trans bus Messages)
P1899: Park/Neutral switch stuck in park or gear (incorrect input state detected for the Park/Neutral switch, auto. trans. only)

Part number of currently installed PCM
P56041534AE

Questions
- Do the codes above suggest the PCM 'thinks' its an automatic ? (i.e. looking for a TCM signal, not knowing if vehicle is in park/neutral)
- Are there specific PCMs for auto vs manual, or are they the same and just programmed accordingly ?
- If there are different part numbers, can someone help me identify correct one for the M/T ?
- Assuming we need to buy a new PCM, any advice on vendors ?

Thanks in advance, this site has been an enormous help.

 

Looking at the parts manual there are a lot of different PCMs and they certainly have different codes depending on engine and gearbox type. So yes, there are Manual and Auto PCMs.

The parts manual can be found here: https://cdn.xjjeeps.com/pdf/en-us/19...ts-catalog.pdf
Page 209 has it all on, engine code ER0 is the 4.0 with transmission code DBB.

Past that I have no real knowledge of this subject. Hope this helps though.

 

Thanks very much for the link, yes that's a big help as I had not been able to find a full parts list like that anywhere. And pretty clear the PCM I've got is for the auto instead of the manual...lovely. But hoping someone else might chime in to confirm the errors are a result of that, would make sense but hoping for some feedback before spending the $ on a new (to me) PCM.

But guess I need to start searching online for this one...56041 531AB.

Thanks again.

 

just stick the part num in google

https://www.fs1inc.com/engine-comput...m-pcm-oem.html

 

Yes, seems to be readily available but still hoping for some clarity on the errors before spending almost $200. Also if anyone has experience with buying PCMs from them...fs1inc ?

 

Reading reviews on Google and BBB complaints decided to stay away from Flagship One, bought one from a highly rated ebay seller instead, we shall see. Will update thread upon receipt and installation.

 

Those codes ABSOLUTELY indicate the PCM is looking for an Auto transmission. There IS NO TCM on a stick shift. (You are the support son) Later XJ's may have the switch on the clutch pedal that MIGHT be associated with the second code mentioned, but I believe it's called something else "officially".

The manual tranny PCM should solve your problem.

 

That must be nice. The P.O. put the incorrect PCM in my 95 (I called the dealer to get the correct part number and it didn't match what was in it) and it took months of watching the used marketplace to find someone selling the proper PCM for a 95 with the AX15.

 

Does the used PCM come with a matching ignition key & barrel ?

It was my understanding that why the resellers program the VIN, to get around the matching key/immobiliser issue

(I have a spare '99 PCM to sell, but no matching key)

 

I did have to provide the VIN for the PCM programming, for exactly the reason you mention, but honestly not sure it matters on mine since its a Sport and does not have the immobilizer far as I know.

Found several re-sellers offering the correct unit, should be here Thursday, fingers crossed it clears the CELs and we pass inspection. My son is pretty jacked to drive it to school.

Still confused as to why they put the wrong one in, and it was something they ordered as it even has a sticker with the correct VIN on it, not like they pulled one from the salvage yard...who knows, sure it won't be the last head scratching we do.

 

If the computer had a Vin sticker matching the vehicle, it's likely that the P.O. swapped the auto transmission out and put a manual in.

 

Would probably agree with you, but have the original window sticker where it shows as a manual 5 speed. And everything is bone stock. Maybe they couldn’t find the right one as you mentioned yourself, or got a good deal, or didn’t bother to check it., who knows. It’s actually running fine, just can’t clear the CEL.

 

That is strange then - you can call the dealer and get the right part number for the computer. Does the Vin sticker look like it was molested, slapped on by a P.O. or maybe a rebuilder of computers? (The 97+ computer is a different style than the 95, neither of which had Vin stickers for me).

The engine should still run fine, the difference between the computers usually is in the transmission handling (basically, since there's no TCM the ECM can't find it - hence the code you're getting) and options between models.
My 95 ran just fine with the wrong computer, but I'm guessing the old one was a manual since it never triggered a code, or maybe the obd1 didn't care..

It's also possible that the computers all have the same components and something got messed up in that one so it thinks it's an automatic and is executing software code paths that are for an automatic that are disabled when set to manual tranny mode...

Who knows, but it's triggered a code for a component that simply isn't present on a manual Jeep, so it isn't right and since usually you need no trouble codes to pass inspection, it's gotta be corrected.

 

Sorry, yes it was definitely a rebuilt component, had a sticker dated 2013, a sticker with the VIN, and one about being “remanufactured”. Guessing they just did a search and bought it without cross checking the part number ����*♂️

It did pass inspection during that period, but guessing they had a shop that didn’t care, or maybe they pulled the bulb for the CEL. Not sure the error code alone would result in a failed test since it’s not really emissions related. But it can’t pass with the light on regardless.

Read a few posts about bypassing the park/neutral signal with a switch, wiring from the clutch to trick the TCM signal, etc. And if I couldn’t find the part I might try it, but as you said I just want it corrected and to move on.

Thanks for all the feedback, will post an update once the PCM is installed.

 

Good news and bad news...the new PCM (correct one for a manual tranny) seems to have cleared the earlier error codes (P1698 & P1899), but now the gauge cluster has stopped working. We ran the diagnostic test holding down the odometer button and the cluster seems to be OK, but only the parking brake, turn signals, etc are showing...no speedo, tach, oil press, fuel...and most importantly no CEL flash during startup, as in it's not working.

Our main goal was to get it inspected which in theory should pass except of course the CEL isn't working.

Any ideas for the gauge cluster are appreciated, or if anyone knows if Texas will pass a car with no problems...other than CEL not working. Thanks.