Hi everyone,

I appreciate any help I can get with my H3X issues. The vehicle is currently sitting in the dealership service department. I have a 2007 H3X with ~67000 miles. I've owned it since March of 2022. I looked, and no old threads seemed to be the same to mine. Apologies if I missed something in my search.

Context

The problems started in August with DTC P2135 (Throttle/Pedal Position Sensor/ Switch A/B Voltage Correlation). The car would intermittently go into limp mode and display errors in HUD: "stabilitrak system, traction failed, reduced power." No idling issues. I couldn't tell what caused limp mode. Turning it off and back on usually reset limp mode and it could be driven again.I'm not a mechanic, so yes, I googled and started shotgunning parts at it. I replaced the throttle body with an aftermarket part. Previous owner tole me he replaced the pedal assembly in Jan 2022. I reset the code with a scan tool. Initially the car drove fine after the throttle relearn procedure. Then, after the first hard acceleration, the car now always goes into limp mode.

After the throttle body replacement I have DTC codes P060E (Internal Control Module Throttle Position Performance) and P0121 (Throttle/Pedal Position Sensor “A” Circuit Range/Performance Problem) and a rough idle after it goes into limp mode. It didn't have the rough idle before. I took the car into a repair shop. This was their analysis:

“Removed intake tubing and commanded the throttle body to open in increments to 100%. Found reading would only go to 36% when commanded to 40% and above. Inspected the connector and harness to find a recent repair to the throttle body connector. Appears that the OE wires were cut and new wires strung from the PCM connector. Found good circuits and reading at each connector of the throttle body connector. Watching live PID data found good data from the throttle body to the PCM while opening and closing the throttle plate.

Ran vehicle with intake boot off and found TPS is adjusting with engine running. Found PCM rejects high snaps of the throttle body and the data flatlines. Internal driver in the PCM cannot handle the data, causing the fault code. Original throttle body most likely took out PCM driver.

Recommend replacing PCM and reprogram. Retest.” The shop wanted a lot of money for what seems like a plug and play procedure after the PCM is programmed.

In Oct 2022 I ordered and tried three different remanufactured and reprogrammed PCMs. 1 from Flashmasters on Ebay and 2 from PCMofNC. The Flashmasters PCM threw weird codes, and the PCMofNC PCMs didn’t fix the issue. All were returned. I can't find a new OEM PCM.

WHERE WE ARE TODAY AND QUESTIONS

I took the H3 to the closest thing I have to a dealer in my area, a Cadillac/Chevy dealer that used to be a Hummer dealer (Denver CO).

I gave them a remanufactured OEM PCM from Rock Auto and asked them to program it and troubleshoot if it didn't fix the issue.

Then sent me an inspection report that said they programmed and installed the PCM, but they think I need to install an OEM Throttle Body because the vehicle "chuggs and sputters". They also said I now have DTC P0603 (Powertrain Control Module (PCM) has failed its own Keep Alive Memory (KAM) self-test).

I think the P0603 is because I had to disconnect the battery in the dark and didn't have the right tools, and I probably didn't tighten the terminals back up all the way.

Here are my questions for the dealer before I replace the throttle body. Any other questions I should ask? Anything I should try?

1. Did the dealer do a throttle relearn procedure, or reset the throttle with the scan tool? Does this H3 need to be driven above 40 MPH for the relearn?
   
2. Any risk of cleaning and reinstalling the original original OEM throttle body to see if that fixes the chugging?
   
3. Are DTC P0603 and a new throttle body potentially related?
   
   1. How does the battery test?
      
   2. Do the terminals need to be tightened?
      

I really appreciate any help and that fact that you made it this far in a long thread.

Thanks

 

Welcome to HF. Should have came here before going to a dealer.

1. Did the dealer do a throttle relearn procedure, or reset the throttle with the scan tool? Does this H3 need to be driven above 40 MPH for the relearn?
2. Any risk of cleaning and reinstalling the original original OEM throttle body to see if that fixes the chugging?
3. Are DTC P0603 and a new throttle body potentially related?
   1. How does the battery test?
   2. Do the terminals need to be tightened?

Answers:
1. Have no idea what the dealer did if you don't. Throttle relearn is, start vehicle with new TB in place and do NOT touch the Accelerator for 3-10 minutes. It relearns all by itself in some time. Once the idle smooths out, done.
2. Not if you use TB Cleaner only and if it does not have internal defects.
3. Nope. If you are still trying to use the Crappy Azzed OEM Battery Terminal Connectors, you found the problem.
1. With a Volt Meter = 12.6V or higher or in needs a charge then retest.
2. No. See below.


Here are your simple solutions. Get it OUT OF THE DEALERSHIP!!!!! Dealers are the LAST place to take an out of warranty vehicle for repairs. This is actually a simple DIY.
A) NEVER use an aftermarket cheap knock of TB. Big part of your problem. Buy an ACDelco TB and swap out the garbage. You might get away for a while on the cheap, but it will eventually come back to make you spend more $$ to replace what you thought was a $$ save. Fix it right the first time.
B) Replace the OEM Crappy Azzed Battery Terminal Connectors with a quality aftermarket set like Stingers or your favorite brand. There are a zillion threads here on that, have at reading some if you care, Known problem. The OEM are junk, after a few remove and retighten = toast. First mod to be done to every H3/H3T to rule out that known source for electrical Gremmlins.

Good luck.

 

Another though.............. almost hurt myself.

Is the recently replaced Accelerator Pedal an ACDelco?

Limp mode can be caused by many issues. A clear example is where either the TB or Accelerator Position Pedal Sensor (APS) built into the H3 pedal assembly do not correlate to each others position. They loose communication, or an unexpected variance is seen by the PCM between the two. The PCM at that point cannot determine what exactly if the driver calling for with the pedal. The default is Limp Mode. Until that correct communication is seen by the PCM, gonna be a lot of limping.

Think of it this way. If you were trying to pull out of the driveway and the PCM mistakenly thought the APS was calling for wide open (floor it), you would be out of control in the neighborhood. So the PCM itself can play a role, but it is always the easy stuff first. New TB, test. Then new Pedal Assembly, test. Making sure each are working properly BEFORE you go to PCM, PCM wiring harness, connectors etc...

By the way, does your H3 have a sunroof? If so, has the passenger side floor been wet?

 

14582A

 

Hey @Doc Olds and @hummerz ,

I appreciate the replies. This is what ended up happening:

I had the dealership put in an OEM throttle body that I bought. I could have done it myself, but the vehicle was already there, and I didn't want to bring it home, install, and then have to take it back for them to troubleshoot some more. With the remanufactured PCM and new OEM throttle body, can was driving great for a few days. Then it died on the way freeway on the way to the airport. The dealer had suggested replacing the MAP connector because they thought one line was loose.

I ordered the MAP connector and installed it. Haven't had any issues since then. I don't know if the earlier pedal assembly was AC Delco. Replace before I got the rig.

I think in my particular case, the issue was the PCM.

I will replace the battery terminals now just for piece of mind. Anybody recommend a good set with a quick disconnect?

Thanks again y'all.

 

Oh, and @Doc Olds , to your question, yes it has the sun roof, but the previous owners did a clean out of the drain valve recently, and I'm aware of the drain blockage issue. I'll make sure to monitor