Recently replaced the entire front bulkhead wiring harness on my 1987 XJ6, but have an intermittent major issue. Two possibly related items?

1. Whenever the battery is connected, the brown and black alternator warning light wire has a +12 V coming through it, and the battery is just barely charging around 12.5 V when running.

2. Also not sure if this is related when the car gets hot or if it’s been driving for a while the car will completely die. Zero electronics. Nothing comes on when the key is removed, re-inserted and switched.

Sometimes I can get it to turn back on by just waiting and then taking the battery leads on and off.

It did this before and after I replaced the harness, as the harness replacement was intended to address some additional problems (which it did, but still chasing some functionality after getting the car running again).

 

Has the ignition switch been replaced? In example #1, is the battery fully charged when taking these measurements?

 

i agree with Slofut, the Ignition Switch is suspect.

 

And they are made of unobtanium.

 

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another unobtainable XJ part ?? First it was the throttle cable, now the ignition switch ?
There must be a conspiracy, when you consider MK-2 / S type ignition switches are available new.

 

Google "Jaguar DAC1607"

They're out there....or so it seems. I wouldn't wait too long before buying one, though!

Cheers
DD

 

I checked, most sites are "Click Bait", ( "this product no longer available).

Moss Motors shows it for $300.00

Norman Motors also shows one for about the same.

I have two old ones, condition unknown.
What goes bad is the rear mounted ceramic section with wiring (the "tumbler" ??), not where the key is inserted. And that part can be dismantled and serviced / restored.

 

Fred get some contact cleaner, D5 is best but there are others that are available from auto parts stores and lowes/H Depot, and Harbour Freight. Uncover the switch and find a convenient access hole to spray it well inside (with the little straw) and operate the switch back and forth a few times. This might clean it well enough to work for a long time to come, at least while you're looking for a replacement.
Bill
As Jose said, you're looking to clean the switch electrical contacts on the back, inside. Not the keyslot and tumblers.

 

it has nothing to do with the ignition switch somehow the black and brown ground to alternator has a positive charge coming through it

 

The black/brown wire isn't exactly a ground wire. Well, sort of.

It should be ground with the engine not running and then go to 12V "+" with the engine running.....providing the alternator is working.

Cheers
DD