Low Power Mode with Wet Roads

[trad04]

Hello,

I have a 2008 H3 that is intermittently entering Low Power mode when I drive in wet conditions. I have already checked and fixed the sunroof tube and have verified that no moisture is getting into the cab in the normal areas (yaw sensor/BCM). The issue appears to be coming from somewhere external but I can't seem to figure out where. On dry days I have no issues, but on wet days it will almost always enter low power mode after some variable amount of time. Then when it sits for a bit and restarts issue dissappear. Any suggestions are appreciated.

 

[08H3]

Any codes?

 

[trad04]

C0240 and P2138

 

[alrock]

Throttle position sensor is a part known to fail, and both your codes suggest that as a possibility.

 

[08H3]

Agreed. I would start there. Or the associated wiring.

 

[trad04]

Ok thanks for the feedback, I have checked the wiring to the TPS and it looks good, but I can try replacing it altogether. Is it common for water to get to this while driving in wet conditions?

 

[trad04]

Just spoke to my son and I forgot that we actually already replaced the entire throttle body about 4 months ago. Everything I find online points to the accelerator pedal sensor. Just not sure how that is related to wet weather since I already ensured that the sunroof lines aren't introducing water into the cab.

 

[Happy Hummer]

Stop. Put down the parts cannon and back away!! Lol!
Start doing some diagnosing. Visually inspecting all wires and testing to see if they carry a load would be a good start. I recommend a back probe and varying test lights. You'll need schematics. Also, the connector at the tb is a known issue with GM based vehicles to corrode and fail. The pedal can also be problematic with the connection and the green crusties.

 

[Happy Hummer]

Also, check and verify your ground points behind the air box and located nearest the abs/ecbm. You'll want to remove these from there bolt/screw and tug test and look for corrosion and clean all this stuff up and reinstall.

 

[trad04]

Ok, I'll have to do some research on how to test for load, but we have visually inspected everything we can get to in the engine bay and under the driver and passenger dash areas. Do you have a photo or specific locations for the grounds you mentioned? I'll definitely check those out. It definitely had moisture getting in when I first got it before I cleaned out and fixed the sunroof tubes.

 

[trad04]

Son finally brought the hummer back home and I was able to look at everything. There is no moisture getting to any of the electronics through the cab on either the driver or passenger sides. It sat in heavy rain all day and did not have any issues after. Then I took it for a drive, hit a puddle, and it went into low power mode. I have looked at all visible wiring and connectors and can't find any issues anywhere. The ground locations in the engine bay look great. Any suggestions are appreciated.