My H2 has some electrical problems. Well, a lot of electrical problems. And I don't know where to start.

It seems that it's most often affected while in rain/snow. Every couple days I'll get "reduced engine power" with some code or another, always relating to the TPS. I used to have it real bad, but replacing the throttle body and it's associated sensors really helped. Now I just carry my scanner plugged in all the time and when I get reduced engine power I quickly clear the code and it returns to normal.

I was on my way home in the driving rain/snow/sleet today when I could feel a slight miss. I've seen this before and it's dried up and gone away. Right as I was turning onto my road I got "service 4wd", and started throwing code P0300 engine misfire not specific to a specific cylinder. I've been all over/under the truck looking for frayed or damaged wires with no success. My transfer case is permanently lit up for N on the dash and when I hit 4wd high/low/etc it flashes for a minute then returns to N. So I can't shift the trans.

I'm fairly certain all this can be chalked up to a bad bundle of wires somewhere but I for the life of me cannot find it. Any suggestions on where to look would be greatly appreciated. I'm at my wits end.

 

First thoughts were either a ground issue or that rain/snow could well be causing a water ingress problem.

This is what I found for P2135 and related issues:-

• Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
• When the TAC module detects a condition within the TAC system, more than one TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
• If this DTC is determined to be intermittent, refer to Intermittent Conditions .

Also see the attachment.

Your other issues may be related...

 

Thanks for the info. I've already replaced the harness going into the TPS and have "wiggled" every wire between the TPS and the pedal with it running to make sure there were no loose connections.

The TAC is the one on the firewall correct? I wiggled that but didn't actually pull the connections. If it's replaced, do I have to do a re-learn process or reprogram in any way?

 

Not sure where it is located or programming requirements, however not all modules are programmable e.g. the Air Suspension Module which I passionately know more about.

If the TAC module isnt not programmable it may be a case of matching matching the GM Part Number to a replacement unit (check for any GM bulletins on number changes)


There seems to be a lot of discussions about cold water and TAC's I also found this which explains more about the system.

Its a lerning curve for all of us!

 

Had a similar issue and it was resolved by replacing the fuse box under the hood and fixing some wire that were chewed by rodents. It would throw codes randomly when it rained, and when some of the bare wires would make contact. I would just take a look and see if you have any frayed wires etc under the fuse box.

 

I have had wires chewed on the under side, I didn't detatch the physical fuse box. I did look everywhere for chewed wires though. I guess I should look under the fuse box.

I replaced the throttle position sensors at the pedal yesterday, which yielded no results. Still P1516 and P2135. I just ordered a new throttle actuator control module before I saw jakeys post. I'll pull the fuse box today and look for chewed wires. I did inspect the TAC on friday and it looked solid, no connection issues, signs of water intrusion, etc.

I did notice when I pulled up my floor mat my carpet was damp. I have a slight drip apparently that is coming from the A pillar, but I can't figure out where it's getting inside.

 

Took the fuse box out, unplugged all hte stuff and plugged it in again. There was no evidence of frayed wires, broken wires, nothing loose, etc. Buttoned it all back up, went around the block. No issues. Took it to the car wash, washed the salt off. Re-caulked the top lights, which I think is where the water was coming in. The lines were all clear from the sunroof, but I took of that wind deflector for the sunroof.