Hello my name is Dale and I have a 1986 Jaguar xjs, 5.3 v12 that will not start.
When I turn the key the dash lights go on and I briefly hear the fuel pump switch on then off.
At the cold start relay I have power at the brown wire and can jump to turn the starter at the red white starter wire.
No spark from coil, no power at + terminal
Cold start relay wires
C1 - R/W. r/w
C2- BRN
C4- w/blue, w/blk
W1- w/blk
W2- w/blue/green, w/yellow
New parts List:
Fuel pump & filter, spark plugs, ignition amplifier (module inside), both coils, and a new battery
Symptoms – Put a new fuel pump in and changed the spark plugs and the car started. So I took it to the wash rack and washed off the car. I drove a short distance and the car stopped running. At first I could crank the starter with no start. Now with the key turned it doesn’t do anything, I do hear the starter relay next to the cold start relay click when the key is turned. I jumped between the C2 Brown wire and the C1 Red White wire and could crank the starter. There is gas in the tank. Tried moving the gear selector from Park to Neutral, and tried wiggling the key. It’s as though something in the ignition just turned off. I have replaced the module inside the ignition amplifier, the primary and auxiliary coils, cleaned and tightened electrical connections. The jaguar was running for like 20 minutes and suddenly shut off after washing it off. I thought that maybe the auxiliary coil in the front got wet. That’s why I replaced both coils. Still the car will not start! And where at first there was power going to the starter, because it cranked right after it stopped running. Now no power comes out of the cold start relay C1 R/W wire to the starter, yet the C2 brown wire (HE+) has power.
With luck someone here will may help me start the 86 Jag!
Thanks! - Dale

 

Oh no!
Did you wash the exterior of the cat, or the engine bay?
Pete

 

I washed the exterior of car and front grill area while jaguar was running...
Dale

 

NO 12v at the +ve of the coil is "usually" an ignition switch electrical issue, very common.

Run a junper wire to the +ve of the main coil, and try again.

The +ve TO that coil comes direct from the ignition switch, no relays/fuses/whatever.

 

Hi Grant,


From where do I run a jumper wire to the +ve of the main coil?


~There is 12v at the brown wire at the cold start relay with the key turned on


Thanks Dale

 

Dale,

That will do.

I would connect to coil first, then the "hot" connection.

Just take the commen sense awareness of not shorting that "hot" wire.

 

Success -> I’m really happy!
~Thanks Grant!
________________
My 1986 Jaguar xjs 5.3L V12 started and ran…
With the cold start relay removed, I used jumper wires from the BRN (HE+) wire to both the RED/WHITE starter wire and to the coil (+) terminal. Then connected I the battery -> She started up and ran for a few minutes before I disconnected the battery again. Yet, I did not use my key in the ignition; just connecting the jumpers at those locations and the battery served to start up the car and enabled her to keep running.
Awesome! – Now how do I isolate or identify what is wrong in the ignition system?
Regards - Dale

 

SWEET.

Now you need to get the electrical section of the ignition lock unit out of the car.

This is fiddly, and once out, it can be opened up and restored very easily.

To get that bit out, remove the lower dash panel, and peering into the area at the back of the switch, you SHOULD see a SMALL phillips head screw at about the 7 o'clock position. Remove this screw, and wiggle the switch out of the lock section.

Seperate the loom connector.

I place the switch in a clear plastic bag, and open the tabs, and seperate the 2 sections. Reason is, there is a small pawl and spring inside that IF it takes off thats it, shows over, you will NEVER find it.

Clean up all the solid grease, and the contact pads. Lube with some electrical grease, sparingly, and reassemble. It can be tested out of the car using an ohm meter and common sense. I then replug it to the car loom, and using a screwdriver I operate the switch to start the car, once satisfied, I then refit to the lock and refit that small screw.