No power and no Fault codes with traction control on

Jeff Diagnostician Australia Posted   Latest   Edited  
Unsolved
Braking
Driveability
2014 Chevrolet Silverado 2500 HD LTZ 6.6L (8 LML) 6-spd (1000)
Reduced Power When Traction Control On. Normal Power When Traction Turned Off

Vehicle brought to us after being at another workshop and had brake pedal position sensor replaced. Fault occurred after brake pedal position sensor replaced had no drivability faults prior. No fault codes in any modules and no warnings on dashboard. We don't have GM factory dealerships in Australia and we have been doing warranty repairs and general repairs on these vehicles for many years. Scan tool data appears normal, we have recalibrated brake pedal position sensor and brake fluid pressure sensor with no change in symptoms. Any Help would be appreciated. Vehicle only has 30.000 kms on it.

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Manuel Diagnostician
New Jersey
Manuel Default
 

Please list all calibration ids in pcm tcm abs

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Jeff Diagnostician
Australia
Jeff Default
 

Thanks have attached.

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William Technician
West Virginia
William Default
   

Have you checked the reduced power history in the K20 ECM data with GDS2?

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Helpful
Interesting
Jeff Diagnostician
Australia
Jeff Default
 

Reduced power history has Reductant fluid low in history. Have checked data and is showing full on all sensors and have done a reset on reductant system also. Thanks.

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William Technician
West Virginia
William Default
   

In the future “reduced power“ has a very specific meaning to us in the GM world. The correct terminology would be "lack of power” or “Low power”. Lack of Power The engine delivers less than expected power. Little or no increase in vehicle speed when the accelerator pedal is pushed down part way. Refer to #PIT5206G. You have a bad brake pedal position sensor or one that has been incorrectly…

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William Technician
West Virginia
William Default
   

The reason you have no message on the DIC is because the system is in brake override mode. The information is in the bulletin. The newer vehicles do not let you powerbrake the vehicle. The ecm limits the engine rpms when it sees the brake pedal is also engaged.

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Rick Diagnostician
Texas
Rick Default
 

Was a brake pedal position sensor relearn performed in the BCM after the switch was replaced? We have seen several vehicle with unusual symptoms until the relearn was performed. HTH

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Agree
Jeff Diagnostician
Australia
Jeff Default
 

Yes we have done the reset and also left battery off over night and carried out reset again no improvement.

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Rusty Owner/Technician
Massachusetts
Rusty Default
 

Sounds to me like it “thinks” it’s got wheel spin. I’d start by looking at the individual wheel speed data.

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Jeff Diagnostician
Australia
Jeff Default
 

Road tested and graphed all wheel sensors and all read same speed but thanks.

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Dwight Owner/Technician
California
Dwight Default
 

Why was the original sensor replaced? Have you tried installing the original sensor to see if the problem reoccurs?

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Caleb Diagnostician
Indiana
Caleb Default
 

Could you please post a pic of the fault as it reads on the dash?

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Jeff Diagnostician
Australia
Jeff Default
 

There is no fault codes and no warnings on dash at all but reduced power when traction control on. switch traction control off and full power returns while still driving.

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Caleb Diagnostician
Indiana
Caleb Default
 

When u say " Reduced Power" you mean it feels like its stuck in "4wd low" or dragging a boat anchor??

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Jeff Diagnostician
Australia
Jeff Default
 

Limited rpm will only rev to around 1300 rpm still changes gear etc but wont rev out until traction switch turned off. Will free rev fine but once driving no power no revs.

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Caleb Diagnostician
Indiana
Caleb Default
 

Can you watch scan data for steering angle, yaw, and lateral accelerometer? Is one of them way off? Are any ABS solenoids being commanded on when this happening?? Can you please give us the voltage on the brake pedal position sensor?

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Jeff Diagnostician
Australia
Jeff Default
 

No abs solenoids activating and yaw and lateral sensors normal steering angle at 0 in straight ahead changes positive and negative when turned.

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Ricardo Diagnostician
Michigan
Ricardo Default
 

Are you doing the bpp and bfp sensors calibration with OEM tools or with autel? I've run into a few times that autel says the calibration is done but there's no difference I then use tech 2 or gds depending on car and it works first try

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Jeff Diagnostician
Australia
Jeff Default
 

Have tried calibration with Autel and also Gscan 3 (i think is gds) but still no change in symptoms. No abs solenoids activating and yaw and lateral sensors normal steering angle at 0 in straight ahead changes positive and negative when turned.

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Caleb Diagnostician
Indiana
Caleb Default
 

No way too get PIDs 2&4 to populate? Is there any change if you unplug the BPP an leave the TC on?

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Tom Diagnostician
Illinois
Tom Default
 

Make sure the brake sensor is installed correctly , seated. Make sure all module sees the same data pcm ,bcm,abs . Hth good luck.

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