Check Engine Light

[CONRAD II]

Ok... Yesterday after leaving work I noticed that not long after starting my sut the check engine light came on. (I have only 17,000 mi) Luckily I have a GM dealer very close to my work and they were more than happy to run a diagnostic test on my truck. I thought the problem could by a symptom of not having my gas cap on properly or something simple like that. However, on my way to the GM dealer I stopped at a red light and turned the truck off. When I re-started the light was still on and my truck had little or no low end power, like it was starting in third gear or something. I drove that way until the next red light (about .25 miles) and then turned the truck off again. When I re-started the light was still on but the truck seemed to be back to normal. It started out in first gear and cycled through normally. When I actually got to the dealer and ran the diagnostic test everything checked out except the following code: P0740. The dealer said it had something to do with the torque converter, but he said that he wouldn't be overly concerned. He then reset things with the diagnostic machine and said to go ahead and drive it for a while to see if the light comes back on. He said he would be supprised if the problem presented itself again, because it was more than likely a glitch. About fifty miles later still no sign of a problem? I plan on visiting my Hummer dealer asap, but I thought you guys might have some insight. Any help would be greatly appreciated...

[CONRAD II]

Ok... Yesterday after leaving work I noticed that not long after starting my sut the check engine light came on. (I have only 17,000 mi) Luckily I have a GM dealer very close to my work and they were more than happy to run a diagnostic test on my truck. I thought the problem could by a symptom of not having my gas cap on properly or something simple like that. However, on my way to the GM dealer I stopped at a red light and turned the truck off. When I re-started the light was still on and my truck had little or no low end power, like it was starting in third gear or something. I drove that way until the next red light (about .25 miles) and then turned the truck off again. When I re-started the light was still on but the truck seemed to be back to normal. It started out in first gear and cycled through normally. When I actually got to the dealer and ran the diagnostic test everything checked out except the following code: P0740. The dealer said it had something to do with the torque converter, but he said that he wouldn't be overly concerned. He then reset things with the diagnostic machine and said to go ahead and drive it for a while to see if the light comes back on. He said he would be supprised if the problem presented itself again, because it was more than likely a glitch. About fifty miles later still no sign of a problem? I plan on visiting my Hummer dealer asap, but I thought you guys might have some insight. Any help would be greatly appreciated...

[H2Singh]

next time press the onstar button, they can do the same online diagnostic while you are driving. Other than that little tid-bit, this is a first I have heard about your problem, maybe some of the hummer "guru's" can advise you.

[CONRAD II]

Light just came back on and the shifting is all f*&^ed up again!!! Goning to the dealer asap!! I am starting to wonder what the hell is going on with my truck that ran perfect just 2 days ago!

[Dan]

My guess is a short in the ignition switch.

[CONRAD II]

the only after market product that I have is a replacement mass air flow sensor... I wouldn't think that would be the culprit. I hope its a quick fix like a ignition switch, nothing major. Anyone have any other ideas...

[Andre]

i have the same problem..look in the tech section

[CONRAD II]

Just got it back, the ignition was the problem. Runs Perfect! Thanks for the help.