So my 2011 xj 120k miles has been freaking out lately…. It started with my radio cutting volume in and out very aggressively and randomly…. Now today on the way home when the radio cut out , so did the car . It began to lurch every time the radio cut out like clock work . When the radio stopped cuttin so did the car….the dash lights up like a Christmas tree with all kinds of warnings…..(ebd fault , gearbox fault , pedestrian something fault , parking brake fault etc . ) I’m wanting to believe it’s a bad ground but I have no idea where to start , yes I have looked at the obvious but will need to dig deeper as this seems to be a physical problem causing electrical problems

 

Uncle Reggie, what you are experiencing is most likely a loose ground connection. If I had to take a guess, it is up, under the dash in the area near the radio and instrument cluster. Out of curiosity, have you recently had some work done on your car that involved them getting into the dash to do the work? If so, that is the area I would be going after. In short, you will most likely have to remove the radio to look in there and echeck every ground point inside the dash to see if there is a corroded junction or if something is loose. I would look more towards the steering column/instrument cluster area than going towards the passenger seat.

As for what is happening, I cannot say precisely, but it iwould appear that your instrument cluster is loosing power and this is sending a signal to the ECU that it should go through a start up secquence. During this, the engine will loose power. This would also give you every light on the instrument cluster as it is doing its start up check. I had a similar problem on my truck where every time I put it in reverse, the instrument cluster would light up. Turned out to be a flooded tranny sensor. But, yours is going to be more with a bad ground.

 

Hi .so I have check at least every ground that I can see and nothing seems to be out of the ordinary with them . They may be some hidden that I cannot reach without dismantling other parts . I’ve also noticed this issue can be replicated with 95% consistency under braking at speeds usually above 30 mph … if I’m going highway speeds and begin to even slightly tap the brake pedal the “cut out “ will start .. radio will cut out and sound as if the sound is far away , and the adaptive headlights light will begin to flicker. The car has givin many “lost communication codes “ but cannot pinpoint if those are because of a possible bad ground or a bad computer is cause the lost communication causing these issues….

 

How old is your battery?
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Possibly oxidation on one or more connectors on the communication networks that connect to a module. Had this on the medium speed communication network. Involved going around the modules 1 by 1 to sort it once and for all. Worst case scenario is a broken wire on the network. Do a search for how to check the CAN network resistance - it's pretty straightforward. Good luck 👍