2003 xj8 always runs good…until two days ago. Had a coolant hose leak all over the top of the engine. Fixed hose and took car to the wash to spray off engine. Long test drive - all good. Next day, after about a 15 mile trip, the dash Trac lights come on. Few minutes later, the car is getting increasingly sluggish from take offs. Then, it becomes clear that the car is not getting any electricity - radio dies, blinkers die, brake lights die, horn etc. Barely wants to take off from stops. A few more miles, the car creeeeeeps into a parking lot with no juice and dies. Turning the key gets me a couple of clicks…nothing. Call a tow truck and wait. 30-40 minutes later, turn the key - cranking, then roars to life. No dash lights - running strong. Cancel tow. Drive car about 10 more miles with the symptoms of losing electricity starting over from scratch and car again eventually barely runs and dies. 40 minutes, repeat => home. So…alternator? Had it replaced about a 1.5 years ago and happy to do it again if need be. But I’m thinking, something maybe got wet that shouldn’t have - maybe in/around the alternator, or somewhere else? How do I test? At the battery? At the ‘false bulkhead’? Any electrical connectors that might have gotten wet (I sprayed it all over in there) that would cause these symptoms? Any ideas or insight is much appreciated.
Jaguar addressed this almost 20 years ago. I dealt with dozens of cars like this when I worked at the Jaguar Dealer when customers washed the engines.
You will just need to find the offending connector or component and clean/replace.
A diagnostic computer to interrogate ALL modules will help find communication faults to modules, networks or sensors that are ‘offline’ or set a DTC for open/short circuit.
good luck.
bob
600-02 Pressure Washing.pdf (26.8 KB)
I don’t seem to have a diagnostic computer laying around. Which is a problem. And I don’t know what a DTC is. So, maybe I will disconnect all the electrical connectors I can find, spray some contact cleaner in there, and leave them open for awhile to dry them out? Is this a reasonable course of action, would you say?
Many people invest in code readers, some are dealer level that can communicate with many or ALL of the modules in the car.
The modules can log fault codes (**D**iagnostic **T**rouble **C**odes) to help with finding problems.
You can save time by reading the codes and concentrating on the areas that the network finds FAULTY.
You can unplug all the connectors to check for water but it will take some time to do that.
bob
Really appreciate your input MCman. One thing I did try first is to put a multimeter probe on the electrical output of the alternator and the other end on the negative battery terminal to see what is coming out the alternator. With car off, I get 12.6 or so volts (battery is good). The with car at idle, I’m only seeing 11.7 or so volts. As I turn on electrical components (headlights, rear defrost, etc), the volts sink into the 10.6 range - and slowly fall as I leave it all on very long. Is this not a dead ringer for alternator failure? I can see the voltage drop (and stay down) instantly as I switch on electrics - implies regulator failure? Truthfully, I am hoping for a bad alternator because I know I can fix that…
Change the alternator it’s toast.