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Discussion Starter · #1 ·
hello all. i have a 4.2 04 with 143600 on the clock. ive been having an issue where using large power draw such as windows or using heat on full blast or anything that highly draws power very suddenly will cause reduced engine power with code p2138 "Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation" which means the value of both sensors within the accelerator pedal do not 'agree' or correlate within their parameter. the issue does not ever occur without manipulating something that draws power (eg. only happens rolling up/down windows, turning on heat) my battery tests well, although i feel that an alternator not properly regulating voltage could be a culprit. ive pulled the accelerator pedal and tested it with a multimeter and it tested fine. recently ive been able to use my windows and the heat at the same time with not much of an issue until today i tried to start it up with the blower already on 5 and temp was on cold instead. the issue occurs as soon as the engine starts. as soon as the ac compressor is engaged after the starter solenoid shuts off, it draws enough power to make this happen. i would love to be enlightened by someone with ideas. thanks guys
 

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I would start by checking all the ground connections you can find, including the negative battery cable to battery negative terminal connection. You might even want to check the negative battery cable for integrity to make sure it is not the problem. Also, there is a "hidden" ground connection in the passenger compartment, under the carpeting just to the right of where your right foot rests on the gas pedal. Those can come loose.

Good Luck!
 

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Discussion Starter · #3 ·
I would start by checking all the ground connections you can find, including the negative battery cable to battery negative terminal connection. You might even want to check the negative battery cable for integrity to make sure it is not the problem. Also, there is a "hidden" ground connection in the passenger compartment, under the carpeting just to the right of where your right foot rests on the gas pedal. Those can come loose.

Good Luck!
would testing the continuity between both the negative and positive battery cable to the starter housing while cranking the engine be an effective way of testing connection?
 

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No it would not. What you describe is sort of a [email protected]$$ed way to do a voltage drop measurement of the positive battery cable from the battery to the starter. To do it properly, you would connect one lead of a digital multimeter (DMM) to the positive battery terminal and the other lead to the starter where the positive battery connects to, and then crank. The voltage displayed is the voltage drop, and only gives you half of idea if the positive battery cable is OK or not.

What you really need to do is to remove both battery cables and measure the resistance of each cable from end to end while flexing the cable all along it's length. The resistance should be zero ohms or very, very close to zero ohms (like .1 or .2 ohms max). While you have the cables off, take a peak at the copper wire underneath the insulation at each connector. If you see green ,then the cable has begun to degrade and the best thing to do is to replace it.

When you reconnect the battery cables to the engine and starter, make sure the connecting surfaces are clean and free of grease.
 
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