Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Procedure (M45)
- Start engine and warm to normal operating temperature. Turn A/C switch and blower switch to ON position. Measure voltage between ground and ECM terminal No. 88 (Pink wire) by backprobing. See. Voltage should be 1-4 volts. If voltage is as specified, system is okay. If voltage is not as specified, go to next step.
- Turn A/C switch and blower switch to OFF position. Turn ignition switch to OFF position. Disconnect refrigerant pressure sensor harness connector located in front of condenser. Turn ignition switch to ON position. Measure voltage between ground and refrigerant pressure sensor harness connector terminal No. 1 (Blue wire). If voltage is about 5 volts, go to step 4. If voltage is not about 5 volts, go to next step.
- Check the following:
- Check for open or short between refrigerant pressure sensor and ECM.
- Check for poor connections at ECM and refrigerant pressure sensor harness connectors.
Repair as necessary.
- Turn ignition switch to OFF position. Check continuity between engine ground and refrigerant pressure sensor harness connector terminal No. 3 (Black wire). Continuity should exist. Also, check circuit for short to voltage. If problem is found, go to next step. If circuit is okay, go to step 6.
- Check the following:
- Check for poor connections at ECM and refrigerant pressure sensor harness connectors.
- Check joint connector-30.
- Check for open or short between refrigerant pressure sensor and ECM.
Repair as necessary. See ENGINE PERFORMANCE and AIR CONDITIONING in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- Disconnect ECM harness connector. Check continuity between refrigerant pressure sensor harness connector terminal No. 2 (Pink wire) and ECM harness connector terminal No. 88 (Pink wire). Continuity should exist. Also, check circuit for short to ground and short to voltage. If problem is found, go to next step. If circuit is okay, go to step 8.
- Check the following:
- Check for poor connection at ECM and refrigerant pressure sensor harness connectors.
- Check for open or short between refrigerant pressure sensor and ECM.
Repair as necessary.
- No problem is indicated at this time. Check for intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. If problem is found, repair as necessary. If problem is not found, replace refrigerant pressure sensor.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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