P0120 and P2135 Reduced Engine Power - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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  #1  
Old 01-11-2010, 11:03 PM
nnolte nnolte is offline
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2003 Chevy TrailBlazer LT EXT
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P0120 and P2135 Reduced Engine Power

My wife's Trailblazer EXT 5.3L gets a P0120 and a P2135 coupled with reduced engine power *very* intermittently. Like once every six months. One time it wouldn't get out of limp mode until I reset the codes. Another time, turning the engine off and on got it out of limp mode (codes obviously were still there).

I am very concerned that she is going to be stuck somehwere and want to get this fixed. I know that P0120 is "TPS1 out of range" and P2135 is "TPS1 and TPS2 out of sync".

Is it pretty much a done deal that I need a new gas pedal assembly or is there something else I should be looking at? Any help is greatly appreciated.
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Old 01-12-2010, 01:47 AM
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the roadie the roadie is offline
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You called it. Very rarely it's a chafed wiring harness between the TPS and the PCM or the fan clutch or its harness (they share the same reference voltage out of the PCM). But you sort of have to start with the TPS if you can't catch it in the act.
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Old 01-12-2010, 08:39 AM
nnolte nnolte is offline
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OK. I'll check out the wiring very closely and then try a new throttle position sensor. I've had problems and replaced the fan clutch before (like many many others) so I'll check the wiring too to make sure it wasn't damaged during replacement.

Thanks for the help.
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Old 01-12-2010, 11:37 AM
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bstromback2002 bstromback2002 is offline
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These are both codes for the throttle body I chased both of them for almost a year and mainly when it was cold outside. I ended up replacing the throttle body.
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Old 01-12-2010, 02:49 PM
nnolte nnolte is offline
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2003 Chevy TrailBlazer LT EXT
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OK. Wait. Looking at the wiring schematic for the Trailblazer (see attachment) I think I had something wrong in my head, the throttle position sensor is the sensor on the throttle body and not the sensor on the accelerator pedal (which is actually the APP sensor).

So it would seem I need to replace a TPS on the throttle body or replace the entire throttle body and not replace the accelerator pedal, right? (after checking the wiring first, of course)
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Old 01-12-2010, 03:08 PM
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Yes you are correct you replace the entire throttle body. Check the wiring back a couple of inches from where it connects to the throttle body, there is a bulletin about chafed wires in that area.
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