HI Casso - see my current post to my “Instrument Cluster Dead” thread.
No idea why it worked, but I followed Williams suggestion to take both battery cables off the battery and touched the positive cable and negative cable together… Mine were too short to touch together, so I bridged them (disconnected from the battery) with a jumper cable.
Connected both cables back up to the battery, started the car, and the instrument cluster is working perfectly again. Would not have believed it if I hadn’t seen it for myself. The suggestion sounded so weird that I almost didn’t try the suggestion, really thrilled I did and huge thanks to WIlliam.
His post suggested it is some kind of “reset”, all I know is it worked when nothing else I have tried did. I was about to yank the instrument cluster and replace it with another used cluster, so glad I tried William’s suggestion first!!! The power of this forum, wow!
John,
If you go to the old site JagLovers(dot)ORG it has photo archives XJ40 search “Bringing to life faulty module relay DBC 10009” or Fusebox service" or “Resolder relay module” you can see some photos.
Dean
Yes I was following your post from the beginning and then my instrument cluster went dead too. I read that your car would start and run and only the panel was dead, the difference with my car was almost everything was dead, it wouldn’t crank over so obviously wouldn’t start and run. I’m glad to hear you have resolved your problem and it was as easy as just touching the battery leads, I’ve no idea how that would work but glad it did, the electrics on these cars just baffle me, I think @Joe77 is spot on, 'our cars do have a mind of their own ’
John I hope it never happens to your car but if it does, or you suspect a cracked / dry solder joint it helps if you use an eye loop or magnifying glass when inspecting the boards ( at least it does with my fading eyesight ) the cracks can be really tiny so difficult to spot.
My understanding: Capacitors in the car’s electronics retain charge to keep car’s memory settings in place so the car doesn’t have to re-learn every time you start up.
By doing a hard reset (touching neg to pos terminal with neg terminal disconnected) capacitors drain and memorized settings (fuelling etc) are erased. Next start up, car goes into learning mode, learns, then saves settings.
That might be what happened to my 75,000 mile XJ6 yesterday. Had not used it in two weeks but kept it on a battery maintainer. Went to the garage to use the car and if fired right up and would run if I kept my foot on the throttle and RPMs up to 1500+, letting it go back to idle it would die, Same result after two restarts. No check engine lights on. Switched to my trusty 64 year old Morris Minor for my errand. Upon returning, the XJ6 fired right up and behaved completely normally. Has not reoccurred since then. Over the two weeks of inactivity the voltage must have dropped because the radio lost its code.
and it was as easy as just touching the battery leads, I’ve no idea how that would work but glad it did, the electrics on these cars just baffle me, I think