Yes, makes sense. The engine computer is very picky about the sensor inputs and can do some odd things when they're wrong. Interestingly, not everyone gets a no-start condition when the coolant temp sensor isn't hooked up or is bad but it does cause assorted issues.

This guy has some good info - this link is specific to the CTS (coolant temp sensor).

Sean's Jaguar Tech Pages - A Coolant Temperature Sensor Emergency Switch

This is probably related to your idle issue thread.

 

Thats Great news! Pleased to see you got somewhere. Just out of interest Which sensor are you talking about? the only reason I ask ask I just finished re-building the wiring on mine, Conceivably mine is an 83 with Lucas Ignition but it started and ran well without the temp sensors connected, maybe someone with more experience will explain further.
Just read that bit about the temp sensor, you learn something new about these cars everyday, must note that one in the book for further reference.
Cheers and good luck to you.

 

if its the 2 wire sensor it could certainly cause a no start.

 

should i replace my coolant temp sensor ? How does this affect my idle issue. Thank you for the info.

 

That makes sense, although I can't imagine what cut it. I had a bad connection to the temp sensor, and my car wouldn't start very easily. The ECU uses that signal to enrichen/lean the fuel mixture. With no resistance whatsoever, I could see the ECU not sending a fuel signal at all to the injectors.

 

my jag wont start again.. It tried to start but died again. i will replace my cts and the harness and go from there...

 

Do you have a digital volt meter? You can test the sensor and the harness easy enough. The resistance values are listed in the ROM. I can send them to you if you don't have them. If this is your problem, you just unplug the sensor, test the resistance value and if it is in range, it isn't the problem. You plug it back in, go back to the ECU, unplug it, and check the resistance values at pins 1 and 5 on my car (I think) and see if they are the same. If not, you start back tracking until you find the problem.
Someone post a quote that says something about replacing parts seldom being effective, but almost always expensive.