Good work.

You've probably already sussed this out but the inhibit switch is on the gearshift assembly. Or, at least that's where it is one later cars.

Sometimes they just need cleaning-adjusting; others times, replacing.

Cheers
DD

 

Thanks

I suspect I might have caused a connection to loosen and eventually fall apart while I was in the center console to fix the stop light error module.

My car has '89 gearbox and therefore also '89 shifter from an XJ12, but I expect the differences to be small.

Next task will be to find out where I have caused a vacuum leak. Car started hunting after maybe 2 minutes idle from cold, but stopped doing it shortly after before I found a leak.
I suspect it's under the car at the gearbox, I have been working a lot around the starter to measure connectivity between starter and relay before I was told that I was working on the wrong relay...

 

Leo
Might be worth a look to see if you have pulled the vac tube off the modulator on the front RHS of the box, just above the sump pan. Also check under the A bank throttle body.

 

Thanks. The modulator vacuum tube was mounted, but rotates easyly. A quite loose fit. Hunting stopped when I moved it around, but it also stopped first time after a short while, so that's no guarantee I have found the cause.
I will check under the A bank TB.

I was wondering if the missing signal from gearbox inhibitor switch could cause the idle to be higher ? I can see in the diagram, that the inhibitor switch connects to other things than the starter relay

 

I do not think so. But check the modulator vac tube at BOTH ends, and the 90 degree fitting, and also if it is soft, replace anyway as it may be porous in the middle somewhere.