Hello all, I have a brief question about a jaguar xjs 3.6 we have in at the moment with running issues. I'd like to know if anybody could check what voltage they get at the ecu pin 5, this is the supply to the CTS I believe.
I am only getting 3.6v out of pin 5 of the ECU from what ive been reading others have said they get 5v which i would expect as other sensors are getting 5v. Please note: Ive checked the wires from the ecu to the CTS and they are all ok in terms of continuity. The car runs fine if CTS is unplugged as I guess it reverts to a base map inside the ecu rather than live data. If others get 5v at pin 5 im hoping thats why the car is running rough as its mis-calculating fuel quantities due to the lack of supply voltage.
Thanks alot.
Jay.

 

If you disconnect the CTS does the 5v on the ECU recover?

If it does I would check the CTS with an ohm meter to make sure the resistance values are good, ie not jumping around, also check the signal wire back to the ECU is not shorted to ground, you will need to disconnect the plug at the CTS & ECU to do this.

 

 

Then I would suspect the problem is the 5v reference in the ECU.

If you have a variable DC power supply you could use this, or 5volts of batteries (4.5v would probably do) to connect to the CTS as the reference and see if the car runs.