02-05 Chevrolet, Buick, Oldsmobile and GMC Mid-Sized Utilities Reduced Power Light On and DTC P1680 P1221 and/or P1271 Stored in the PCM - kw fan clutch SES light power MIL 4.2 LL8
| Subject: | 02 - 05 Chevrolet, Buick, Oldsmobile and GMC Mid-Sized Utilities Reduced Power Light On and DTC P1680 P1221 and/or P1271 Stored in the PCM |
| Models: | . |
The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.
Condition/Concern:
Reduced power light on and DTC P1680 P1221 and/or P1271 stored in the PCM
Recommendation/Instructions:
Monitor the 5V reference to the Accelerator Pedal Position ( APP ) sensor, circuit 1274, using Peak Min/Max on a Fluke 87. Refer to Si document 1454678 for the 5V reference schematics. Command the fan clutch control "on" with the Tech 2 at 50%. If when commanding the fan clutch on, the 5V reverence spikes to battery voltage, the concern is the 5V reference shorted to battery voltage intermittently inside cooling fan clutch. Replace the fan clutch to repair this concern.
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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.
Models:
(02 - 05 Chevrolet Trailblazer and Trailblazer EXT) and (02 - 05 GMC Envoy, Envoy XL and Envoy XUV ) and (02 - 05 Buick Rainier) and (02 - 04 Oldsmobile Bravada)
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