Intermittent dead pedal

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99Dyna

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06 GMC Yuk XL Denali. 220k miles, runs great except......every so often, when taking off from a stop, when i push down on the throttle pedal the truck will start to move, but then its as if the throttle linkage/wire was disconnected. The truck idles, doesnt bog or make any odd sounds from the engine. So i push the pedal down about 1/2" and keep it there, truck will start to move, then makes some gear or motor sound from low in the dash, the rpms drop to idle, the truck stops moving, i have to lift off the pedal, push back down and truck will start to move again. If i take off from stop and push the pedal down more than say 1", everything is fine all the time. Brought it to 4 shops and nobody can figure it out. Of course it doesnt do it when i take the mechanic for a ride. Shows no codes, disconnected neg cable for 5+mins to "reset" and didnt fix issue (i read to do that somewhere). Figure its the Throttle Position Sensor, so got new pedal, then got new throttle body, but issue still persists. One mechanic said that the pedal assembly is the pedal, a motor, and sensor, but I thought that is all 1 piece. Not sure where to look next.
 

rockola1971

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Check wiring for intermittent open (broken wire(s) from the plug to around 8" up the wiring harness from TPS. Are you getting a "reduced engine power" on the instrument cluster?
 
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99Dyna

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Check wiring for intermittent open (broken wire(s) from the plug to around 8" up the wiring harness from TPS. Are you getting a "reduced engine power" on the instrument cluster?
No reduced engine power or anything. Once that dead pedal comes on, if i push pedal all the way to floor, that engine just idles, i hear some gear whining noise, and that would be it. Then i lift off pedal and all is ok. Other than this issue, the truck is great. Well, sometimes, like twice a month, it does have trouble starting, like not enough fuel. Kinda cranks, and coughs, for 3-5 seconds then starts. Forgot about that. Had all the fuel lines and vacuum lines checked and all was good. Did a pressure test.
 

bigdog9191999

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where are you located? it would be curious to hook up and do some data logging when it does this.

as mentioned above is probably tps and or actuator, or the position sensor on the pedal. unless you have a wiring issue, which there has been known issue to the tps. seems like dorman has a replacement plug for these also
 

OR VietVet

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No reduced engine power or anything. Once that dead pedal comes on, if i push pedal all the way to floor, that engine just idles, i hear some gear whining noise, and that would be it. Then i lift off pedal and all is ok. Other than this issue, the truck is great. Well, sometimes, like twice a month, it does have trouble starting, like not enough fuel. Kinda cranks, and coughs, for 3-5 seconds then starts. Forgot about that. Had all the fuel lines and vacuum lines checked and all was good. Did a pressure test.
As has been said, this is a known problem with the drive by wire rigs.
 

Scottydoggs

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check your truck for abs codes in history, need a abs scanner to see them. my truck gets a dead pedal with tc is on and it detects a wheel spun, then the pedal just goes flat out dead for like 5 seconds. no abs lights or check engine light nothing lights up. but i get a abs code in history. if i turn the tc off it dont do this ever. if i hold the tc button in for 8-10 seconds to turn off stability control it finally flashes a service stability message on the cluster. i suspect my issue to be the ebcm.
 
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99Dyna

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where are you located? it would be curious to hook up and do some data logging when it does this.

as mentioned above is probably tps and or actuator, or the position sensor on the pedal. unless you have a wiring issue, which there has been known issue to the tps. seems like dorman has a replacement plug for these also
Im in New Philly Ohio. If it was a wiring issue, wouldnt it at any pedal position? This only happens with the first maybe 1/2" of pressing down on the pedal and it doesnt happen every time.
 
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99Dyna

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check your truck for abs codes in history, need a abs scanner to see them. my truck gets a dead pedal with tc is on and it detects a wheel spun, then the pedal just goes flat out dead for like 5 seconds. no abs lights or check engine light nothing lights up. but i get a abs code in history. if i turn the tc off it dont do this ever. if i hold the tc button in for 8-10 seconds to turn off stability control it finally flashes a service stability message on the cluster. i suspect my issue to be the ebcm.
I'll ask my guy if he can check for ABS codes and next time a drive truck, i'll turn off the TC and see what happens. Thanks
 

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