I have an 03 XJR that is misbehaving. About a month ago I ran over a piece of a truck tire that flew off a truck right in front of me. Immediately I got ASC not available, ABS not available, and ENGINE FAILSAFE MODE on the display and the car would not go over about 5 mph. I stopped the engine and restarted it and everything was OK. For about 1000 miles. Without cause the same messages and the car would only go 5 mph. Restarted and OK again. No check engine light or fault codes either time. After another 300 miles same thing only I got a check engine light, fault codes P1637, P1638, P1642, P1642, P1720, and P1797, BRAKE FLUID LOW, and TRANSMISSION FAULT.

I put in a new battery and the problem started reoccurring after ~ 30 miles. But now I could drive 60mph with the ENGINE FAILSAFE MODE in the display. I had the ABS module rebuilt and still have the problem. I don't get all the codes all the time. P1638 is the only one that occurs every time. All the codes are related to CAN BUS errors. Also when I turn on the ignition the climate control display shows "ER" and beeps ten times.

I have had the car on a lift and gone over the underside looking for damage and could not find anything. The only electrical cables under the car are for the ABS sensors and transmission they look OK. I checked the resistance to the wheel sensors and they are all 1100 to 1300 ohms and no shorts to ground. (If it was an ABS sensor I should get an error like P1165 or P1175, but don't get those errors.) I have cleaned the connections to the ABS module and the ECM.

Any ideas where to go from here?

thanks
Dave Christensen
03 XJR
69 OTS Etype
65 OTS ETYPE

 

Hi Dave
Welcome to the forum.
Last October we also were getting P1638, P1641 and an assortment of other DTC fault codes, but P1638 almost everyday for at least 2 months.

It turned out that the Instrument Cluster module was causing all the DTC codes.
I purchased a used one on Ebay for $89 that was a close fit to our existing ref numbers and software release code in early December 2011.

No more P1638 DTC codes, the replacement process was just plug and play.

We started getting P1120 and p1121 DTC fault codes for a few weeks in August this year (2012). We had the throttle body repaired at ASI on Ebay for $326.

This also was a plug and play replacement process.

All seems well for the last 2 weeks.

Jim Lombardi