ECU Firmware Version Info Needed

Can someone please let me know what the current version of the ECU firmware would be for a 2000 XJ with the 4.0 and AW4? I can't seem to find this info anywhere.

When I was looking up ECUs for my '98XJ I ran across some information that said the last two letters on the part number for the ECU would determine the firmware version. For example, AA would be version 1, AB would be version 2 and so on and so forth. In my searches, I found an AF part number (but this is for a '98XJ ECU).

You probably already know this and I don't know what the most current version for an '00 would be...

TerraWombat said:

When I was looking up ECUs for my '98XJ I ran across some information that said the last two letters on the part number for the ECU would determine the firmware version. For example, AA would be version 1, AB would be version 2 and so on and so forth. In my searches, I found an AF part number (but this is for a '98XJ ECU).

Click to expand...

IIRC, the ECU part numbers determine which firmware load the ECU should receive, not necessarily the version of the firmware itself. I think we may be saying the same thing in different ways, though

Just curious, why are you asking this? Building your own ECU?

TerraWombat said:

When I was looking up ECUs for my '98XJ I ran across some information that said the last two letters on the part number for the ECU would determine the firmware version. For example, AA would be version 1, AB would be version 2 and so on and so forth. In my searches, I found an AF part number (but this is for a '98XJ ECU).

You probably already know this and I don't know what the most current version for an '00 would be...

Click to expand...

This is correct. After 15 years of working at Chrysler dealers I have never heard of it referred to any other way. The only way to know if your software is up to date is to check the PCM number with a scan tool, write down the number, and contact someone at the dealer level to run your part number to see if it can be updated. Without the number it is just a guessing game.

SleeperXJ said:

Just curious, why are you asking this? Building your own ECU?

Click to expand...

Maaaaybe

The long-term goal here is to come up with an ECU arrangement geared towards engine swaps. There are two basic ideas I'm looking into; right now I'm just figuring out which approach may be more feasible. None of them look particularly good on paper, but this is all very preliminary right now.

Idea #1: run two ECUs - the factory one and the third-party one for whatever engine is installed. Use the third-party ECU to handle keeping the engine running and the factory one to handle instruments, etc. I can see this potentially being really complicated from an interface standpoint between the two ECUs as well as having to modify the software on both ECUs to suit. It would almost certainly require a 'translator' box to be plugged in between the two ECUs; think of how Montana Fab's AW4 shifter Override works only on a much more complicated scale and you won't be far off.

Idea #2: run only the third-party ECU, firmware-adapted to the XJ. Depending on the design of the ECU in question, it may not be possible to fully interface with everything the factory one normally controls / samples. Custom wiring harness required to connect that ECU to the XJ's wiring bus.

Idea #3: same as above, but using a factory ECU. This raises the same basic issues.

Like I say, it's all just in the is-this-feasible stage right now. Figured I'd start with whatever on the OEM side is current as a baseline and go from there - and, while I'm glad to see that there are a couple of open-source ECU projects out there (FreeEMS, OpenECU, etc.), they're not really going in the directions I want to take.