Hi guys, I am having a weird electrical issue with my XJR and I wanted to see if anyone else has experienced something similar. I started getting a bunch of strange electrical faults at once and it is even affecting my aftermarket stereo. Just as a note the stereo is new speakers, headunit and amp and I've installed the same setup in 2 other X308s with no problems, one that has had the system for 5+ years and over a year with no issues in the current XJR.

Anyway Failsafe engine mode keeps coming on randomly and goes away. I have replaced all the vacuum lines and the brake switch when the cruise control failed about 10K ago and had no issue until now. The traction control light also comes on but once again the ABS module was replaced about 15K ago when it failed and no issues. In addition the electrical fault message has flashed a few times for a couple of seconds and disappeared. Recently the car started losing all power until I moved the battery cover. I suspected a loose wire but both terminals are tight, no frayed wires and the junction box behind the spare tire looks clean and all bolts are tight. The battery is one year old. Finally the stereo is bugging out where it has started randomly tweaking and sounding really loud and distorted.

For all these issues to happen at once I am suspecting a ground problem, possibly the ground strap from the trans bell housing to the frame. Another possibility is the ECU is failing but that wouldn't affect the stereo and I know these cars are VERY sensitive to voltage changes. If anyone has some insight or experienced similar symptoms the help is appreciated, thank you!

 

The first basic checks to do:

1. Check the voltage on the battery terminals while the engine is running; what do you get?
2. Check if any of the battery cables is warm/hot while the engine is running; the cables may look very good but they sometimes lose good contact inside their crimped ends.
3. Check (clean, tighten) the connections at the false bulkhead in the engine compartment.