When I open the drivers door, the interior light comes on. So far so good, but so do the HVAC fans at a very low speed. Both light and fans go off together when I close the door. With ignition on, all heater functions work normally.
I just finished replacing the heater core. Thinking this must be a bad ground. Column and instruments came out to do the core.
Mark,
Many years ago my fans started coming on when they shouldn’t. Turned out to be a failed diode that was supposed to prevent feedback from something else that came on. I realize this is kind of vague, but it was a long time ago.
To track it down, you have to carefully study the electrical schematics, looking for diodes that could form a circuit if failed. In my case, it was an inline diode… a Jaguar part packages in a black plastic case about 1/2" x 2" x 1/8".
Ed Sowell
Thanks for the info. I’ll check it out. I just noticed another detail - when the problem is present, the interior light is dim.
So in summary :
Ignition off, door open, heater fans on low and interior light is dim.
Mark_SF,
I recommend that you provide info on what year and body type (coupe,
cabriolet, convertible) in your post. Jaguar produced many configurations
of the XJ-S/XJS from 1975 until 1996 and it would help others to know which
kind you are having this problem with.
Paul
Good point, it is an 86 XJ-SC.
Fixed it. The ground for the interior light switch was bad. The wire disappears behind the screen demister vent on the upper left, so rather than take everything apart, I added a new ground wire, and everything is back to normal.