Hello, I have a weird one. I have a 91 XJS with a V12 I recently rebuilt and included a new gear reduction starter. The car was recomissioned after being parked for some years due to engine issues. The car runs great, but the problem I am having is the car does not crank/restart once it has been driven for a period of time. It always starts cold, but once driven for 20 or more miles, nothing, no click, dead. I originally thought it was the starter relay under the hood, but after swapping out about 4 of those, I realize now it must be something under the dash. I can start the car every time by pulling the hot and the starter wire off of the relay and arcing them together. The car cranks right over and starts immediately but it is rather annoying to pop the hood to start the car. As I recall, there is another relay under the dash somewhere that coud be defective, or the starter switch itself is defective. I don't believe the starter relay is receiving the start signal from the ignition switch/relay in the cabin. There is not even a click from the relay when I turn the key to start. Other work arounds are simply to install an override start button from the relay, but that is kind of a backyard fix. Thoughts? Thanks for your help.

 

Do you have a test light ? or voltmeter?

A couple preliminary checks

Next time you have a 'no crank' condition see if the white/yellow wire at the starter relay has 12v +"+ with the key turned to start. If not, suspect a problem with the ignition switch

Also check the the black/green wire at the starter relay is ground with the gearshift in P or N. if not, suspect a faulty or misadjusted neutral safety switch

Cheers
DD

 

Thanks!

 

Check out the Fuseable Link on the Battery Positive in The Boot Trunk (Its basically just a joiner with a Fuse that pushes together) so give it a good clean

The Fuseable Link can become disconnected just by looking at it! Often when changing the Battery

Or more likely got jolted apart on a drive out

Its almost on a 'Hair Trigger' and only require a small amount of movement to disconnect it and then when you turn the Key you get nothing! not even a 'Click' failing that try cleaning the Lug on the Self Starter