2.5L Backup ECU Hunt ~ 1986

[White_Comanche]

I'm inspired to get a backup ECU ever since @Pete posted that recent PSA about this critical piece. 'Cause no working brain box equals no vroom-vroom.

 

My ECU is original, and judging by how it looks it could last my lifetime, but ya never know. Below are pictures of it, and a closeup of the label.

 

I'd like to know:

• What year(s) of MJ & XJ ECUs work in my 1986 2.5L Manual Transmission?
• What Part Number(s) should I be looking out for?

• Will computers from donors that have automatic transmissions work as well?

 

Also, are any of the 2.5L compatible years better than others? I've read that 4.0s can get a small performance bump when installing the right one. Thought I'd ask to see if there's been any new insight discovered.

 

Appreciate all the help guys. I see a lot of these on eBay, but very few that look exactly like my ECU.

 

 

[eaglescout526]

Good news! You have a better range of ECUs to choose from than 4.0L guys. 86-90 ECU is basically the same. I think 87-90 is an upgrade for 86 Renix 2.5Ls as it does away with the WOT switch and relies on the power steering pressure switch to control the fuel ratios. Oh and auto ECUs are gonna be next to impossible to find so I wouldnt worry to much and I think the 86 auto isnt that much different from a manual ECU. 

 

Also youre ECU isnt original. It is era correct but it should have a AMC part number and should say made in france vs mexico.

[Minuit]

Reminder: I'm still waiting on someone to send me a failed ECU and/or TCU for investigative purposes.

[eaglescout526]

10 minutes ago, Minuit said:

Reminder: I'm still waiting on someone to send me a failed ECU and/or TCU for investigative purposes.

Oh I have a failed ECU. The fuel pump circuit doesn’t work and fails to prime and let the coil fire off a spark. 

[White_Comanche]

Hey Eagle, do I search for ECUs like this? I've been seeing a little more than anticipated.

 

Just curious... why am I not seeing any real continuity between the numbers on these labels vs the others that look in this style?

 

Or are these a looping range of part numbers?

 

 

 

 

 

 

 

[eaglescout526]

Yes you’ll search for ECUs like that.
So there’s two labels. The silver one is direct from the manufacture and that’s their part number. Also the date of manufacture can be found below francs. So that one was made the 25th week of 86. 
 

I do believe the part number changes and I’ll have to post the whole list to show you but essentially 86-90 is the same ECU. So you’ll probably see some different numbers and box’s that will say Renix or Bendix. But essentially it’ll be a looping range of numbers that are more so just tied to each model year. Hence why 89-90 got difference ECUs part numbers for the 4.0L than 87-88 but we also know they updated the program for the 89-90 ECUs there. Chrysler didn’t touch the 2.5L as it already was running at peak. 
 

The one on your ECU is a reman ECU. Shame they painted it and took off the original label, morons.