Ford Repair Questions? Ask a Mechanic for Answers ASAP
Have you been able to check for any trouble codes in any of the modules on the vehicle?
Just wondered if you had any other codes besides P1290.
Was the sensor you replaced behind the alternator on the cylinder head?
Ok. We will need to check the wiring between the CHT sensor and the PCM (Engine Computer) which will require a digital multimeter that can measure dc volts and OHMS (resistance). DO you have a meter? Since the sensor did not fix the problem, it is either the wiring or the PCM. If there is an issue with the CHT sensor or those codes are in the PCM, the AC will not turn on.
Ok. We will need to unplug the sensor and disconnect the PCM wiring connector. Then we will need to measure the resistance (OHMS) between the sensor connector, wiring harness side and the PCM connector harness side.
Disconnect the battery also when testing for OHMS or you can damage the meter.
Place one meter lead on the (WHITE/VIOLET) wire at the CHT connector and the other lead on pin #38 on the PCM connector. Then wiggle the harness around. Your meter should read 0.0 OHMS.
Then test the (BROWN/WHITE) wire at the CHT connector and pin # ***** the same way. Below is a picture of the PCM connector so you can locate the pins.
It is mounted under the dash on the passenger side behind the glove box. See below.
What does the meter show when you touch both of the leads together?
Ok, you do have a wiring issue between the CHT sensor and the PCM. Inspect the wiring harness and follow it from the CHT sensor to the firewall to the PCM.
Also, check the connector on top of the engine. It is a rectangular connector. Below is a picture of the wiring in that connector C192. Do the same test from the CHT to that connector with it unplugged and then do the test from the other side of the connector to the PCM. This will tell us if it is on the engine or between that connector and the PCM>They are pins #P and #R