Possible causes – A/C system low or over charge with refrigerant– Faulty A/C refrigerant pressure sensor– Cooling fans in-operative– A/C refrigerant pressure sensor circuit open or shorted– A/C refrigerant pressure sensor circuit poor electrical connection When is the code detected?

Possible causes – A/C system low or over charge with refrigerant– Faulty A/C refrigerant pressure sensor– Cooling fans in-operative– A/C refrigerant pressure sensor circuit open or shorted– A/C refrigerant pressure sensor circuit poor electrical connection When is the code detected?

Possible causes – A/C system low or over charged with refrigerant– Faulty A/C Refrigerant Pressure Sensor– Cooling fans in-operative– A/C Refrigerant Pressure Sensor harness is open or shorted– A/C Refrigerant Pressure Sensor circuit poor electrical connection When is the code

Possible causes – Air leak between the MAF sensor and throttle body– Dirty Throttle body or Mass Air Flow (MAF) sensor– Throttle Position (TP) sensor not seated properly– Faulty Throttle Position (TP) sensor– Faulty Mass Air Flow (MAF) sensor When

Possible causes – Battery charge– Faulty Generator– Generator harness is open or shorted– Generator circuit poor electrical connection– Engine Control Module (ECM) controlled generator– Faulty ECM Tech notes The ECM is detecting a high turn-on voltage at times. Possible causes

Possible causes – Battery charge– Faulty Generator– Generator harness is open or shorted– Generator circuit poor electrical connection– Engine Control Module (ECM) controlled generator– Faulty ECM When is the code detected? The Engine Control Module (ECM) has fault detection circuitry

Possible causes – Battery defective– Loose or missing alternator drive belt– Faulty alternator– Open or short system voltage circuit Tech notes Higher than expected voltage problems are most likely caused by bad voltage regulator. The voltage regulator is part of

Possible causes – Cooling fan harness and connector– Faulty cooling fan When is the code detected? The P0526 code is detected when the PCM has detected a loss of cooling fan speed signal and the condition is present for at

Possible causes – Deterrent key not programmed to vheicle– Faulty Deterrent key– Fualty ignition switch– Poor electrical connection for Deterrent circuit components Symptoms – Engine Light ON (or Service Engine Soon Warning Light)– No or hard engine start situation P0513

Possible causes – Deterrent key not programmed to vheicle– Faulty Deterrent key– Fualty ignition switch– Poor electrical connection for Deterrent circuit components Symptoms – Engine Light ON (or Service Engine Soon Warning Light)– No or hard engine start situation P0633

Possible causes – Dirty Oil– Engine mechanical problems– Faulty camshaft position sensor– Faulty crankshaft position sensor– Timing belt jumped Tech notes There is a factory service bulletin for the following GMC models: 2004-2009 GMC Envoy2004-2009 GMC Conyon2004-2009 GMC Envoy, Canyon

Possible causes – Dirty Oil– Low engine oil level– Faulty Exhaust Camshaft Position Actuator Solenoid– Exhaust Camshaft Position Actuator Solenoid harness is open or shorted– Exhaust Camshaft Position Actuator Solenoid circuit poor electrical connection– Faulty Engine Control Module (ECM) Tech

Possible causes – Dirty Oil– Low engine oil level– Faulty Exhaust Camshaft Position Actuator Solenoid– Exhaust Camshaft Position Actuator Solenoid harness is open or shorted– Exhaust Camshaft Position Actuator Solenoid circuit poor electrical connection– Faulty Engine Control Module (ECM) Symptoms

Possible causes – Dirty Oil– Low engine oil level– Faulty Intake Camshaft Position Actuator Solenoid– Intake Camshaft Position Actuator Solenoid harness is open or shorted– Intake Camshaft Position Actuator Solenoid circuit poor electrical connection– Faulty Engine Control Module (ECM) When

Possible causes – Dirty Oil– Low engine oil level– Faulty Intake Camshaft Position Actuator Solenoid– Intake Camshaft Position Actuator Solenoid harness is open or shorted– Intake Camshaft Position Actuator Solenoid circuit poor electrical connection– Faulty Engine Control Module (ECM) Symptoms

Possible causes – Dirty throttle body– Electric throttle control actuator misadjusted or damaged– Faulty Electric throttle control actuator– Intake air leak Tech notes If there are no intake leaks, clean throttle body, adjust engine idle and erase engine code. If

Possible causes – Dirty throttle body– Electric throttle control actuator misadjusted or damaged– Faulty Electric throttle control actuator– Intake air leak– Poor electrical connection to the Intake Air Control (IAC) valve Tech notes If there are no intake leaks, clean

Possible causes – EGR passage clogged– Faulty EGR Valve– EGR solenoid valve harness is open or shorted– EGR solenoid valve circuit poor electrical connection Tech notes EGR flow malfunction could be caused by a clogged EGR valve or EGR tube.

Possible causes – EGR volume control valve stuck open or closed– Faulty EGR volume control solenoid valve– EGR volume control solenoid valve harness is open or shorted– EGR volume control solenoid valve circuit poor electrical connection– EGR temperature sensor and

Possible causes – EGR volume control valve stuck open or closed– Faulty EGR volume control solenoid valve– EGR volume control solenoid valve harness is open or shorted– EGR volume control solenoid valve circuit poor electrical connection– EGR temperature sensor and