Good day all!

i have purchased another Jag, an early 1989 XJS with the Lucas CEI. I have a fair amount of experience with the D-jetronic system in my pre-HE XJ12, but always wanted an XJS. Well, I finally have my dream car! It’s not pretty, and it wasn’t a runner. I’ve solved the non-running issue by diving into the ignition amp/module issue, sorted out the firing order (I always seem to find cars with incorrect spark plug lead orientation) and am diving into getting this car ready for some serious miles.

I have ordered the updated ROM, though I’m not too pleased with how it’s organized. Nearly identical to the manual I have for my pre-HE, just added and more confusing supplements to the end of the book. The wiring diagram is handy though. What I can’t seem to source, are these two wires in the wiring loom that connects to the distributor and to the ignition amp. From what I’m tracing in the book, I’m 99% certain the amplifier wire in this loom is the tach, in fact that’s pretty much the only thing it can be. But what the devil are these two wires? I grounded the wires and went loop testing at the ECU connector with no luck, so I’m a bit lost as to what these were for?

The 4 wires in this pig tail/loom

Dark green solid and a light green/white stripe wire.

 

those are for the one of the switches on the Throttle pedestal. kick down one I think. I'm sure someone else will chime in before i get home

btw you can ditch the dual ignition coil system (if its not already gone) for the single one. The single one is square looking and attaches to where the round one shown in your pic is

 

I already have the new coil coming in, DAC6093

The transmission kick-down switch that is triggered by a rolling cam on the throttle actuator is currently connected. Is there something else off that loom?

 

found a pic.

This switch beside the pedestal. Lhs

 

Curious, that switch is on my 76 XJ12, but missing on mine. I noticed the same kind of switch was moved to the throttle actuator itself and figured it had changed in the 10+ years.

So there are two sensors mechanically triggered by the throttle actuation aside from the TPS?

 

Sure enough, took a look at my XJ:


Here it is on my XJ

And my XJS has that missing, even some witness marks from the little bracket that sandwiches the mount. Odd.

 

maybe they went to replace it and broke the very small bolts and left it. cleaning up a PO stuff is the hardest part in owning an XJS. I think its part of the cruise control system. Do you have cruise control? does it work?

 

Has your car had a transmission swap? If they removed the TH400 maybe they got rid of the kick down switch at the same time.

 

Not sure yet, just picked this up on Friday and haven't been able to get it on the lift yet.
From everything I've been going through, someone did NOT know what they were doing with this car. Spark plug leads were in a terribly inaccurate order, sensors bypassed, etc. They were shotgunning this thing just to get it running.