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Home >> GMC >> 1997 >> Forward Control 4.3 W, L35, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Controls - Tests W/Codes - 6.5L Diesel (P Series)) >> Diagnostic Trouble Codes >> DTC P1656 - WASTEGATE Solenoid Control Circuit >> Diagnostic Aids

Diagnostic Aids

WARNING: This page is about a different variant/trim than selected.

This diagnostic will set when control circuit does not follow PCM command (when solenoid is requested on, voltage will drop; when solenoid is requested off, ignition voltage will be present). Scan tool has a 5 second on time abort. Wastegate solenoid can be commanded on as many times as needed in 5 second intervals. DTC P0236 may also set when DTC P1656 is set. This diagnostic can be checked at key up. Engine will not respond to scan tool commands at idle (engine unable to achieve boost pressures greater than BARO at idle) or at any engine speed greater than idle (PCM control abort to prevent engine damage).

Fig 1: Wastegate Solenoid Control Circuit Diagram
G96B29521