Question about 2004 Chevrolet TrailBlazer

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Reduced power light/ service on 2004 trailblazer accelerator pedal does nothing 8 mph max. This happened after long trip when I did a short stop. Tried again turned ignition off and on after traveling 1 mile slowly and appeared ok.

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  • Ron Glazer Jan 04, 2011

    Thanks for this comprehensive answer. Would a scan tool such as the Equus at $88.52 do the job? My mechanic wants to hook it up to the computer and charge me $90 to read the codes. Is a scan tool the same as his computer (If so obviously his would be more sophisticated). Is it possible to have mechanic read the voltages using a volt meter to check voltages and not have to pay for computer?

  • Ron Glazer Jan 04, 2011

    Great answer. I used other help services and did some research on my own, but this was by far the most comprehensive!

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  • 10,515 Answers

Hi,

Your truck has a system that is called "throttle by wire" installed in it. What this means is that there is no actual throttle cable, the throttle plate is actually opened and closed by the computer. The reduced power light will come on when there is a problem somewhere in this system. If there is a loss of signal from any of the position sensors, the system will go into a reduced power mode and you will have virtually no power at all. Turning the vehicle off and back on will reset the fault until the next time the fault is present. A diagnostic trouble code will also be stored in the computer that will pinpoint where the failure was (or is.)

This is usually caused by a bad Accelerator Pedal Position Sensor (APP Sensor). It is located on a bracket above the accelerator (gas) pedal.


ACCELERATOR PEDAL POSITION SENSOR VOLTAGE (4.2L)

© 2008 Mitchell Repair Information Co., LLC.

Throttle Position (1) Volts

At Idle

APP Sensor No. 1 Less Than 1.1

APP Sensor No. 2 Greater Than 3.9

Wide Open Throttle

APP Sensor No. 1 Greater Than 2.0

APP Sensor No. 2 Less Than 3.0


(1) Measured at sensor or as seen on scan tool.

Let me know,if needed further assistance.

Hope i helped you.

Thanks for using ' Fixya ' and have a nice day!!

Posted on Jan 04, 2011

  • taran_2005
    taran_2005 Jan 04, 2011

    Thanks for your response!!

    When a fault is detected within the system, the Powertrain control
    module turns the Check Engine Light on (engine symbol), stores a fault
    code and displays "Reduced Power".


    90% of the time, the
    failed component is the throttle body itself. It has internal sensors
    that fail, and are not serviced separately.
    The only way to know for
    sure though, is to have the module scanned for codes, to see what was
    stored. Parts for this system are expensive, so accurate diagnosis is
    key. Often times, places like parts stores will performance an "OBD" scan
    for free, in hopes of selling you parts. If you can't find such a
    service, you may need to take it to a shop and have it looked at.
    The
    fuel gauge is also a common problem, but its not related to the vehicle
    not starting. Most of the time, the sending unit in the tank is bad,
    which will require tank removal. Its about a $70 part and about 3 hours
    labor to perform that job.

    Be advised that i would prefer dealer to take care of it as i have seen many times autozone and other stores would sell you parts that is usually not required ( wrong speculation ).However, if you have the trust on your mechanic, that is absolutely fine.

    Let me know,if needed further assistance.

    Hope i helped you.

    Thanks for using ' Fixya ' and have a nice day!!

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I replaced my accelerator pedal position sensor on my 03 trailblazer because reduced engine light came on and when gas pedal pressed it did nothing. with new sensor it still does nothing, what do I do


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What causes the "Reduced Engine Power", "Service Stability Control" and "Traction Control" warning lights to come on?


the "Reduced Engine Power", problem causes the PCM to disable "Service Stability Control" and "Traction Control" turning on the warning lights to come on for those systems . The reduced engine power is because of a problem with the electronic throttle control system or as GM calls it TAC system . Reduced Engine Power Mode
When the PCM detects a condition with the TAC system, the PCM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:
• Acceleration limiting--The PCM will continue to use the accelerator pedal for throttle control, however, the vehicle acceleration is limited.
• Limited throttle mode--The PCM will continue to use the accelerator pedal for throttle control, however, the maximum throttle opening is limited.
• Throttle default mode--The PCM will turn OFF the throttle actuator motor and the throttle will return to the spring loaded default position.
• Forced idle mode--The PCM will perform the following actions:
- Limit engine speed to idle by positioning the TP, or by controlling the fuel and spark if the throttle is turned OFF.
- Ignore the accelerator pedal input.
• Engine shutdown mode--The PCM will disable fuel and de-energize the throttle actuator.
© 2017 General Motors Corporation. All rights reserved.



Drive by Wire training Your best bet , take it to a GM dealer

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Reduce Engine light on; battery light on; low charge from charging system; vehicle won't run faster than 30 mph


You may have damaged the ECM with a power surge from shorting out the alternator. Try to reset the CPU program using a code reader and look for fault codes while you are at it

Jan 26, 2014 | 2004 Chevrolet TrailBlazer

2 Answers

Chevy Reduced Engine Power and Auto Gear Transmission


still sounds like another sensor is bad. take it to shop and have it tested would be my suggestion. good luck.....

Aug 13, 2012 | 2002 Chevrolet TrailBlazer

1 Answer

Error code p1271 on trailblazer


That trouble code is faulting the accelerator pedal sensor. The APP sensors are located in a TAC module mounted to the accelerator pedal bracket. There are three individual APP sensors within the TAC module. Three separate signal circuits, low reference circuits, and 5v reference circuits are used to determine the accelerator pedal position. The APP sensor signal voltages increase when the accelerator pedal is depressed.

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2 Answers

My 2004 trail blazer has codes of 2101 1516 and 601. replaced the throttle body accuator and throttle body. still get the codes but can be erased unless the temp ouside is less than 30 degrees and the...


The code P0601 means the internal memory of the PCM (computer) has failed self-test. The PCM may need to be reflashed or replaced. The other codes will probably go away after this.

Feb 04, 2011 | 2004 Chevrolet TrailBlazer

1 Answer

Check engine lite is on, power lost lite is on. code p1276comes up. replaced throttle body, but no change. volts at vac fuse 14 both sides. will not accelerate over 1800 rpm's. 2004 trailblazer with 6cyl.


Your CODE P1276 refer to the Acelerator Pedal Position, Sensor 1 Circuit Range Performance.

Probable cause: Wiring, APP or ECM


GM - P1271 Accelerator Pedal Position Sensor 1-2 Correlation

I also found this... though its for Trailblazers... but may give you a clue:
Reduced Engine Power Message and/or Check Engine Light with any Combination of the following DTCs: P0107 P0112 P0122 P0452 P1120 P1220 P1221 P1271 P1275 P1280 P1481 P1515 P1540 P1633 P1635 P1639 P1682 #PIP3192 - (Oct 18, 2004)

Reduced Engine Power Message and/or Check Engine Light with any Combination of the Following DTCs: P0107 P0112 P0122 P0452 P1120 P1220 P1221 P1271 P1275 P1280 P1481 P1515 P1540 P1633 P1635 P1639 P1682 PCM Repeat.

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Condition/Concern:
Reduced engine power message and/or check engine light with any combination of the following DTCs: P0107 P0112 P0122 P0452 P1120 P1220 P1221 P1271 P1275 P1280 P1481 P1515 P1540 P1633 P1635 P1639 P1682

Recommendation/Instructions:
If the SI diagnostics did not isolate a concern, the following information may be helpful:
- Inspect the main engine wiring harness between the PCM and the generator assembly for a potential short to ground. There is a metal wiring harness retainer in this area that secures the main engine harness. If the harness conduit is mispositioned, some of the wiring may become exposed and chaff on the harness retainer. This may eventually cause the exposed circuit to short to ground.

- Inspect the 3 harnesses that connect to the PCM for potential shorts to ground on the metal PCM mounting bracket, just below the PCM. There are plastic harness retainers on the PCM bracket that secure the harnesses to the PCM bracket. If the harness conduit is mispositioned, some of the wiring may become exposed and chaff on the PCM bracket. This may eventually cause the exposed circuit to short to ground.

- If a chaffed circuit is found in either of the above locations, repair the circuit using the necessary SI procedures. Once the circuit is repaired, tape the area of the affected area of the harness to prevent the wires from becoming exposed in the future and secure the harness using the original harness retainer.

This applies to 04:
- 4.2L 5.3L LL8 LM4 Engine with DTC - P2120 or P2122 or P2123 or P2125 or P2127 or P2128 - kw low MIL pedal power reduced #PI01746 - (Feb 17, 2004)
- 4.2L 5.3L LL8 LM4 Engine with DTC - P2120 or P2122 or P2123 or P2125 or P2127 or P2128.

When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.

Condition/Concern:
MIL light on. Reduced Power message on DIC. Possibles DTCs P2120 and/or P2122, P2123, P2127, and P2128.

Recommendation/Instructions:
The APP harness is clipped to the accelerator pedal bracket. The harness may chaff on the upper portion of the accelerator pedal causing a short to ground. Verify the harness is not chaffing on the accelerator pedal. After repairing the short, reposition the harness to ensure no contact between the harness and the accelerator pedal.

Hope helpes.

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2 Answers

Code drive 5 . My 2004 trailblazer posted a code "drive 5". It showed the "reduced engine poweer" light, and would not respond to the accelerator pedal. I had been driving in slow traffic. I pulled over,...


Thottle body sensor, accelerator pedal sensor, restricted air flow...will all trigger this fault light. Go to your local Autozone, they will run an OBD scan for free, and explain the fault codes to you so the correct repairs can be made.
Good luck...i hope this helps, please rate me a fixya.

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1 Answer

2003 Trailblazer loses power, I am getting codes P1271 and P1271p/d


#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) 
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) 

Jul 16, 2009 | 2003 Chevrolet TrailBlazer

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