09 Caravan A/C clutch operation

I wanted to share this fix with you all. This 09 Caravan had no A/C clutch operation and P0533-A/C PRESSURE SENSOR CIRCUIT HIGH stored and current in ECM. The A/C pressure sensor reading in ECM and TIPM (Totally integrated power module) showed around 5 volts and 450 psi which was inhibiting A/C compressor operation. TIPM supplies 5 volt reference and ground to A/C pressure transducer on RH side of engine compartment behind air filter box and then processes signal voltage and sends signal information onto ECM so ECM can determine A/C clutch operation. See attached diagram.

Tested for 5 volt reference and ground to A/C pressure sensor. Found 5 volt reference but no ground. When I supplied ground to the sensor ground wire my pressure reading in TIPM and ECM went to 0 volts and 0 psi. Strange ... there must be a short between the signal wire and ground wire. I removed connector from A/C pressure transducer and also from TIPM and load tested signal, ground, and 5 volt reference and verified no shortage to power or ground or to each other. I tested powers and especially grounds into TIPM and all were OK. I determined that the signal circuit and ground circuit must be shorted internally in the TIPM since we had no ground on ground wire but rather the 5 volt bias voltage from the signal circuit. Grounding the ground wire or the signal circuit gave us the same result of 0 volts and 0 psi as i stated earlier.

I replaced Totally Integrated Power Module assembly with Reman Mopar and installed new A/C pressure transducer just in case old sensor had caused TIPM to go bad. Left key on for 12 seconds after TIPM installed per instructions for TIPM to download vehicle configuration data from the other modules and A/C compressor engaged and worked properly and A/C pressure transducer readings were correct in TIPM and ECM.

Regards