That drawing is timeless

 

Almost ready to go in.



Anyone know what these numbers and tags mean. I figured the 3.58 one myself.

 

@AVOS- any word on the TCM?

 

Not yet, he is traveling for the moment and will return next Tuesday, but he is aware of it, so hope he will already have some time to think about it.

 

Have you tried driving it with the code to see if the trans shifts at all?

 

How odd it may sound, I don’t want to brake anything when I can avoid it, so would like to take steps carefully.

Actually I have no doubt that the TCM will work as such (I am not getting an “incorrect part fitted” error) so could give it a go, however the behavior will not be representative/useful imo due to the ECU going in a sort of limp mode, so I don't have the urge to try (yet).

I see if I can sniff the CAN bus, that will probably reveal the true issue, but will be for the weekend.

 

I noticed that there seems to be a secondary plug that plugs into the connector that than plugs into the TCM. The connectors on my car look very fragile so I'd just double check all the connections.

Since you're only getting one code I was thinking that it's just a communication's issue.

 

Heads Up to those upgrading to the HU15 (older) diff.

I'm quite glad I got the front plate locally with the HU15 diff. You will have to do some fabricating for the exhaust hangers so don't throw the old one into the dumpster just yet.

Here's the old bracket next to the "new" mounting plate.





and done:

 

 

Adam, good work so far, how are you going to tackle the flange issue? Use one of those adaptors? Any thoughts on prop alteration? is there any need?

 

Are you talking about the pinion flange for the jurid coupling?

 

This is the perfect time to install poly bushings in the rear as it is out of the car. I am sorry I never mentioned that the plate had to be modified for the exhaust, but it has been a few years & many mods ago.

 

Which bushings are you referring to?

 

Yes..

 

I'm not sure what it depends on but when I was looking for the diff I noticed that the junk yards would specify 3 bolt or 4 bolt.

I got a 3 bolt out of the XJ12 and the flange is the same pattern as the 3 bolt on the original diff so no modifications to the flange were necessary. Besides the exhaust hangers it's a direct swap.

 

I put it together today. The exhaust sounds awesome.

I took it around the block and as soon as the trans shifted into 2nd I got a message "Transmission Failure".

I tried a few things like keeping the rear ABS sensors disconnected, disconnecting ABS, disconnecting the CAN bus line from the TCM, and all it gave me is more trouble codes. The trans will not shift and goes into limp mode as soon as the car doesn't know how fast it's going.

@AVOS - please let me know once you know more as I don't see a way around getting the TCM reprogrammed.

 

Have just send the CAN scan, hope that I have done it right and will help. So when we have solved the DTC issue, it will still require fine tuning to get it right (at least that is what I expect), so guess at least 2 to 3 weeks from now before it will be ready. I hope I get another TCM soon now, as that might speed up the process. I’ll get back to you in a couple of days, and will check if he can do just a ratio change (unless you want to wait for a full tune).

 

Well the car is stuck in 3rd gear. The 3.58 makes it surprisingly driveable in this 1 gear only. Also I noticed that when I clear codes when the car is running the check engine light goes out and stays out while the trans code cones back which makes the motor feel like its out of the limp mode but the trans is still locked up.

 

Somehow my post got cut off. I'm not sure if it's OK to drive the car stuck in 3rd. Anyway, would it be possible to do the gear change only in the TCM and than an upgrade to the tune once it's ready?

 

ok guys, what do you think of this?

1998 XJR with 4.2 and 3.58 rear end - YouTube