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Sudden Unintended Acceleration on GM vehicles caused by water short in the connectors. The focus of this report is the 2007-2011 GM full size trucks and the connectors.

Through extensive research and tests between August 2019 and September 2020, I have determined that water intrusion into the instrument panel (IP) to body harness connector 205, which carries the APP sensor signals to the ECM/PCM has the potential to cause sudden unintended acceleration in some of the 2007-2011 GM full size trucks. Water can short connector 205 through body leaks and/or condensation. This may cause an increase in voltage on the APP signal circuits that does not exceed the predetermined value to trigger a code. Water in connector 205 on these vehicles can also potentially cause a malfunction in the BPP/Brake switch status circuit.

I have also determined water intrusion into the connector 109 on the full size truck line has the potential to cause false activation of the APP circuit.

I have confirmed this by simulating a water short in connectors 109 and 205 by using jumper wires and water. I have confirmed that water can cause the voltage to increase on APP circuit 1 and APP circuit 2 and not exceed the predetermined value to trigger a code and enter reduced power mode on GM vehicles. It all comes down to surface area exposed as to the final voltage change. As these vehicles become older and seals start leaking more, the likelihood of the APP circuits shorting increases. Because of the known water leak into the connectors containing the APP wires and verification that water can cause false activation of the APP circuits, it is my conclusion that in rare events this water could increase the voltage of both APP signals in some of the 2007-2011 GM full size trucks. One example is if water is in contact with the 5 volt reference and the two APP signals in the correct amount, the ECM can misinterpret this as the accelerator pedal being pressed. A second is the voltage to sensor 1 and sensor 2 could be shorted to 5 volts but sensor 2 is also shorted to ground such as in connector 109. There are many possible combinations of voltage changes that could be caused by water in connector 109 and 205 that the ECM may not recognize as a fault and cause the vehicle to accelerate with out driver input.


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Man am I Ever glad my trucks still have a throttle cable. I really dont want a complete computer controlled vehicle ever, just enough tech to maximize fuel efficiency and that's it.

Thanks for sharing this info... I assume this is another "unknown" problem gm won't admit.

What made you decide to diagnose this.... a dangerous situation?

Al
 
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Understand... thanks for sharing.
 
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