'03 TB, V-6 Reduce Power light with codes P1221, P1271, P1635
July 26th, 2008, 3:39 PM
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'03 TB, V-6 Reduce Power light with codes P1221, P1271, P1635
Have a 2003 Trailblazer, V-6 with about 80K miles. The SES light has been on, but recently started getting the Reduce Power light. Now theReduce Power light comes on right away. Error codes are always P1221, P1271, and P1635. My wife always runs the fuel down to just fumes (she won't listen) and it's pretty hot out here in Arzona. Was wondering if that's related as I thought this might be fuel system related? Anybody have any experience with this? Any help is greatly appreciated!
July 27th, 2008, 9:12 AM
#2
RE: '03 TB, V-6 Reduce Power light with codes P1221, P1271, P1635
#PIT3138A: 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 - (Nov 1, 2004) [/align][/align]
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
[align=left]
Models:
.[/align]
[hr]
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.
.
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) [/align]
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
[align=left]
Models:
.[/align]
[hr]
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.
.
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) [/align]
November 8th, 2008, 10:09 AM
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RE: '03 TB, V-6 Reduce Power light with codes P1221, P1271, P1635
Just wanted to say thanks on this one! (Better late than never.) It was the fan clutch. When I finally had the fan clutch out you could see that there were two broken wires where the wiring harness enters the clutch. Pretty obvious in hind sight. Thanks again for your help!
May 23rd, 2013, 4:59 PM
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Reduce Engine power SES light PLEASE HELP
I have replaced computer, throttle body, 2 app sensors, cleaned sensors, went through the wiring, I am tired of guessing and having dealerships tell me they do not know what to tell me. This reduce engine power every 10 mins or less or more for 4 months is getting on my very last nerve. 
December 20th, 2018, 10:50 AM
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#PIT3138A: 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 - (Nov 1, 2004) [/align][/align]
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
[align=left]
Models:
.[/align]
[hr]
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.
.
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) [/align]
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
[align=left]
Models:
.[/align]
[hr]
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.
.
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) [/align]
Last edited by lakicha freeman; December 20th, 2018 at 10:52 AM. Reason: Wrong spelling
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