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Old 08-19-2017, 04:13 PM
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Default Hummer h2 2003 reduced engine power


my hummer 2003 h2 had check engine light on and reduced engine power. Clear the code back on the road, drove for few miles and code came back few times, got these few things done to fix the issue:

Replaced the throttle sensor at first that didn't do the trick,
second time
replaced throttle body, (with gm parts) not aftermarket
and it was running great up tp 1600 miles after 1620 miles reduced engine power came back on again.
Now i am tired of this problem. I have changed the accelerator padel sensor as well and it gave me code 2 times today after doing all this!
If someone could please help me out with this issue
what do i need to do with this madness!!
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Old 08-21-2017, 06:27 AM
H2 Chief's Avatar
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Look at your temperature gauge, is it overheating? Hummer does this as a safety feature. Just a thought..
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Old 08-23-2017, 09:12 AM
Join Date: Apr 2010
Posts: 88

There are a few common issues that can cause this problem,

A wire breaks about 6" from the throttle body in the harness,
corrosion at the plug on the TACM,
Disagreement of the position sensors
Loose grounds

Do you have a way to pull the freeze frame data record to see what was going on at the time the code was set?

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Old 08-24-2017, 04:21 AM
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Location: Birmingham (UK)
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The "codes could be very significant, what were they?

Last edited by oceanbrave; 08-29-2017 at 04:40 AM.
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Old 08-28-2017, 05:13 PM
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Join Date: Jul 2012
Location: North of Denver
Posts: 36

I had a guy crack the temp. sending unit and it put the ECM into reduced power mode on another GM 6.0 LQ4 engine. Check the connection at the temp sender, check the temp sender.

Otherwise, spend the $100 and have someone with a TECH II find the problem for you. Otherwise you are just throwing money a the problem.
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