Another traction/ reduced speed problem alpha 5.3

[Empigt]

I'm having a problem with a 2008 hummer 5.3 alpha h3. This problem has been going on over a year now. Only codes thrown are o2 sensors and low voltage to from ignition switch. I've read about all sorts of problems causing this. So my first go to was the throttle position sensor. Did that with no fix. Installed a new ignition switch, still no fix. Put new speed sensors at each wheel. Still no fix. I checked for any broke or wore wires in the engine bay. Pulled the plastics off the harnesses and nothing broke or wore. I seemed to notice if I wiggled wires under the dash it would start. So I thought the aftermarket keyless entry/remote start may be causing the issue. So I had a professional rip out the old system that had a chip key bypass module, and install a new full system. That didn't work either. But the hummer seems to start better when it's cooler so if it starts in limp mode if I run the a/c and get the cab cooler inside, then shut it off and then start it it will start in normal mode. So far have invested close to $1500 just trying to fix this issue. I hate going to a dealership as I know how much of a rip off artist they can be. I had a friend take his convertible to a dealership because the power top wouldn't retract correctly. The said a new top assembly was needed at the cost of $3000. He brought it to me to see I I could repair it. It took me 5 minutes to look it over and find an small folding umbrella and fallen behind the seat into the top bow assembly lodging it. Pulled it out and all was fine. And I'm sure that dealer ship saw that and was about to charge $3000 for what I just did for free. Sorry to make this so long. Any help would be great. Thanks.

 

[Empigt]

Also forgot to mention. I replaced the battery and cable ends. And master window switch on the drivers door as it wasn't locking any of the doors except the drivers door. The switch did fix that. But not the reduced speed problem.

 

[alrock]

You may want to put up the specific codes as that may help others help you. It does sound like a wiring issue, and those with more experience than me might be able to help you troubleshoot. Like I said to another poster today, those aftermarket remote starters tend to cause issues.

 

[alrock]

One thing to think about with remote starters and the like. Typically these are installed with Scotchlock connectors. Those connectors use a guillotine type blade with a cutout to strip the plastic insulation and contact the wire. However, I believe it's likely that it may often cut a few strands of the wire. That wouldn't be an issue if those cut strands always stay in contact with the metal guillotine, but if they pull back over time as the wire flexes and bounces, you may effectively reduce the overall gauge of the wire, thus limiting connectivity.

It's just a theory of mine, but I believe it's one of the issues that affects vehicle's electrical systems.

 

[Empigt]

That was my thoughts as well. And the newly installed keyless entry remote start. I told the guy so he didn't use those but instead soldered all connections and liquid electrical taped the connections. I'll have my code reader here tomorrow and pull the codes again. I did find a broken wire at the oil pressure sender. Funny thing is the oil light seamed to work normal on with the key then goes out after starting it. But fixing that hasn't helped either. I wish I had a full scan system that would read voltage from all the systems and sensors to help narrow it down.

 

[Empigt]

Pulled codes again today and got 2 new ones. P0449 p0452 both having to do with the evap system. Will those through it into reduced speed? I checked evap wiring to the canister in the rear and the purge pump on the engine. Saw a video on checking the purge pump by unplugging it and the hose to the rear canister and starting the engine then checking if the outlet for the rear hose sucks your finger. This one didn't so the purge pump isn't stuck open. Check hoses to the rear for cracks. None that I saw. So still looking for what's going on.

 

[Empigt]

Well after a year of this thing giving me hell and buying all kinds of parts. I finally tracked down the problem. It was the green plug itself that goes to the ignition switch. And that plug ain't cheap. Simple 5 wire plug ranges from $59 to $102. I found out 07 and newer Saturn's use the same plug on their ignition switches. Local u-pull-it had a few Saturn's so got one for $2.00. Not a bit of trouble now the last 2 days. It now starts every time hot or cold. Still need to look into the evap codes that the hummer it throwing.