found a new plug. but the wires going to the coolant sensor and the air sensor were broken. they have been spliced into several times–not me, with different color wire. traced original wires back to the right had side. i have a yellow/black------yellow---- blue/orange and a red/blue… the old coolant plug wires are yellow/green and black. my new plug wires—coolant plug-- are white /green and a white/purple. the air sensor plug wires are both white then turns into a red/blue and a yellow /black. my question is, what goes where correctly thanks. michael 85 xjs
Coolant sensor wires are supposed to be UC and YB. Air temp sensor wires are supposed to be RU and YK. Note that the YK wire is also connected to the throttle pot.
If everything is a complete mess, you might skip the wire colors and trace leads straight to the plug on the ECU in the trunk. The coolant sensor is supposed to be connected to terminals 19 and 5. Note that terminal 19 is connected directly to ground within the ECU. That’s the YB wire.
The air temp sensor is supposed to be connected to terminals 20 and 21. The YK wire that’s also connected to the throttle pot is the one connected to terminal 20.
Y/B=yellow black U=blue, what is C? think i found the wires, just need to replace splices. does it matter which wire on the new plug or does it matter which wire goes to which side???
I have no idea what C is. Isn’t that weird? It’s not one of the letters on their legends, but it looks pretty clear on the diagram. It might be a G or an O that got cut off to jamb the wire color label in a tight space; the spot where it’s marked is very snug indeed, but they coulda just moved the marking over to another spot along the same line.
Both the air temp sensor and the coolant temp sensor are simple variable resistance devices. As long as neither lead is grounded internally, it shouldn’t matter which wire goes to which side. You can confirm the terminals are not grounded with a VOM.
Don’t mix up the air temp sensor with the coolant temp sensor, though.
ok, thanks for the info
Michael,
My copy of the 1990/1991 Model Year XJ-S S57 Electrical Guide shows the Coolant Temperature Sensor wires as Blue-Orange (UO) and Yellow-Black (YB). As already mentioned by Kirby the Air Temp. Sensor has Red-Blue (RU) and Yellow-Pink (YK) wires.
As far as I know Jaguar didn’t use the letter “C” for any color wiring.
Paul
thanks Paul…now have to cut back to em wires. multi splices not by me. thanks