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I bought an 89 XJ that had a working non-renix engine in it. Over the course of the year, it began to run rougher and become harder to start. Turns out it is quite the Franken-build.
We pulled the current ECU (part no. 56027532) which turns out to be from a 91-92 Cherokee/Commanche depending on which site you are looking on. It is for a MANUAL but my XJ is an automatic. Current mechanic who is trying to sort this out is recommending an ECU (part no. 56027887) which seems to be for a 94' Cherokee or Commanche.
I have gone to several websites trying to determine what part to order based on the harness clips, but one site has 15 different choices for a 91-92 for an Automatic.
I cannot go back to the shop where I bought the XJ. Tried to help out a friend whose business was failing, now the shop is closed and he has ghosted us.
Any help would be appreciated.
Last edited by 96ss2283; Jan 22, 2025 at 06:58 PM.
Reason: doubled photos
I think you have a '89. with an AW4 ? The VIN is an '89 and it does have an automatic but someone before me swapped engines, not sure what year it is
What year engine ? I am not completely certain, but the current ECU was for a MANUAL, part number shown in the picture
What harness/connectors ? Shown in the pictures
How did you get it going? It was running when I bought it but has gradually been getting hard and harder to start, now it will not start unless the ignition is turned to on for about 4 minutes, then it will turn over and run super rough
Why do you think the ECU is faulty, and not some other problem? That has been what the people who have been trying to solve the issues are down to, but truthfully they are not 100% sure
did it ever run well ? It ran well enough in warmer months, but was hard to crank and had a huge backfire right before turning over
What is your auto electrical knowledge? ZIP, that is why I am asking here
I know 0 about Renix. 94 is the first year XJ in Oz, but I do have extensive auto electrical knowledge>>>> DEFINITELY NOT A RENIX ENGINE
here is some things you absolutely must do if you want it running again for any reali$tic $
* download the relevant FSM from cruisers website, I will add a link and a link to that and the OBD1 technicians diagnostic manual
What /Where is cruiisers website?
* identify engine and GB year via entering serial numbers into Chryslers website
* ID harness via this forum
* do some proper diagnostics (using the OBD! link I post) Not seeing any link?
(Hopefully that is the manual written by Chrysler to train their techs back in the day on OBD1, has flowcharts, and is just what you need, download it from my Google Drive.)
Let me know if it is not accessible
As to the other manuals, they are on cruiser54 website, he is the (late) founder of this site. Search his name and navigate to his website.
There are many manuals there for you to download
You need to one that cover your Chassis year and Engine year, so that is why you need to ID the engine via its serail nuber with the online checker
have you done that yet?
Do not be phased when it talks about the DRB1 tool. You do not need it.
A multimeter is needed, it is written for mechanics to understand electronics, so its very handy, but you still have to do some reading
I got a 1990 renix and my ecu dont look nothing like that, and my renix ecu is in the cabin, not engine bay. My jeep has the AW4 automatic and it has its own separate tcu.
You will need to find out what model injection system you have, and if your ecu also is a tcu in one u it or if indeed yljr tranny has a seperate tcu like my 1990 renix jeep.
I have had excellent luck with buying used good ecu's on ebay, for good price, and they have return warrentees via ebay.
There are professional ebay sellers that list a wide range of ecus.
perhaps you can provide photos of your engine components so that smarter folks than me can determine year model injection system you have, also provide any
art number that are o your ecu. look under the dash for the tranny tcu
The renix has a spark coil near the battery. my bids 2001 xj has coil packs for instance, and a fuel rail over the injectors, so it is visually different.
Rockauto has several for a 1992 xj with simular but different part numbers, note they have federal and California emissions versions, and police versions It might be a federal and california are interchangeable so long as you dont need california smog test???
For the above rockauto listings, see the part numbers AND the discription for what they fit, automatic, federal, california etc.... If your engine is right for the ecu you have, it is a 1991 federal engine, but came from a manual shift xj. So id be looking for a 1991 Federal Automatic replacement ecu which Rockauto lists as either a 56027528 or a 56005717 Rockauto says out of stock but others should have that part number
This one on ebay below is a 56027528 which per rockauto site is a 1991 federal automatic. From the info you provided this should work, it is a federal like your current ecu, it is a 1991 like your ecu, BUT it is for an automatic instead of a manual.
per ebay photos, the 91 thru 95 ecu have the same shape. the 90 on down ecu is renix and looks different squared off shape and it is i side the cabin, the 96 on up looks different than yours also. so it appears the 91 thru 95 has same shape, and likely are simular, but it also appears from first website on top of this post that 91 and 92 use same, but not 93, 94, 95 It appear the last three digits represent difference within a series of ecus such as federal verse california, and maybe might also mean police, and perhaps other things like minor tweeks within year models or such. So an exact match of last three digits may not be needed, perhaps, not for sure
Here is a 1993 VIN # plus ECU . I swapped my ECU as you can see because of charging issues.
An "S" at the 8th position in the VIN refers to an Automatic (AW4) which is what I currently have
I jump started a 4x4 which had a dead battery off my 97 xj now engine light is on i have codes for both 02 sensors and a coolant sensor reading is it possible i have problem with ecu
coolant sensor will have an Ohmic value ( 1k or a specific # from the spec.) easily trouble shot
the 02 sensors most likely are ok but there voltage value is extremely low # , would have to have a special tester
The ECU , in my case had issues with startup and idling when cold.... COULD not get the ECU REBUILDER to answer questions. there screwballs .... good luck to you.
The biggest mistake is ordering a unit that's similar to the year. Within a single model year, there can be a ton of variations for different transmissions. I'd first run the VIN to figure out what the factory configuration was. You can get a factory window sticker at https://carfast.express/en/vin_decoder . This will at least give you a baseline from which to select the correct ECU.
Last edited by dolliessoul; Feb 14, 2026 at 10:53 AM.
ECU help need
