My Hummer H2 cranks, but won't start. It has new alternator(just installed), and battery(fully charged). It quit coming home one night. It kinda would die and come back. It did it 2 or 3 times. The bat light came on, then quit all together. It would crank, but not start. Wasn't long the battery died. Got it towed. Next morning it started, so i let i run(it was charging). Come back in 15 min, and it quit. Got it restarted (alt was not charging). Wasn't long it quit again. Installed a new alternator, and battery. Truck started ten quit. Charged the battery for a couple of hours. It started, and ran fine. Came out next morning....cranks, but won't fire. No codes on the laptop, no blown fuses, got gas, fuel pump cycles with key.......WTF???

 

Are you sure your Battery terminals are properly secured? Loose terminals cause all kinds of crazy problems.....

 

And check the other end of the ground to make sure it is securely attached to the frame (or engine block or wherever they ground out a H2).

If you REALLY want to get all geeky-like, hook up a multimeter to one of your power outlets (cigarette lighter) so you can monitor the voltage as you drive or try to start your H2. If you are having a system wide power failure it will show on the meter. If the voltage holds but you are still having problems then you know you can start checking other possible issues.

 

Well after some more tinkering a crank sensor code came up. I replaced it, and it still didn't start. I fooled with it, and it started up, and ran like crap. then it quit again, and wouldn't start. I had it towed to the local chevy dealer. They fooled with it for awhile. They found out it had a improperly installed viper alarm, with remote start. They removed it, and fixed a couple of wires. It started right up, ran for 5 minutes, and quit. They did some more testing, and found out the PCM was fried. They ordered a new one that will be here tomorrow morning. They will program it, install it and let me know how it goes. Good news is that everything will be covered under warranty except a couple of hours of labor to remove the alarm, and fix the wires.

 

Just curious: How long has the Viper alarm been in your Hummer?

 

Ok just got back from picking up our Hummer. Apparently that was the problem because she runs great now. Darn computers.....lol....Only had a $200 bill too, and they changed the oil, and washed it. Great guys.

Oh I don't know how long the viper alarm has been in it I bought it used. It is a 2007 with 60k. Aparently it was installed wrong.

 

Thought I would post an update on how things are going.......

Well after driving it home the next morning it quit again. I turned around, and took it back. I barely made it there. It quit 3-4 times, and wouldn't start. They looked it over, and found 4-5 wires corroded in the man harness right by the PCM. They cut out the corrosion, and spliced in some new wires. So far so good. It ran from Iowa to Maryland fine, and fine around here. Guess that fixed that problem.......

However while driving the check engine light comes on. It is a P0420 code. (Catalyst system operating below efficiency bank 1) I clear it, and keep riding it comes back. Getting more, and more frequent. So I call the dealer to see if it is the cat, and if it is covered under warranty. He says yes, and yes. So I contacted a local dealer and took it to them. They ended up replacing the y pipe and cats along with an O2 sensor. No code so far and it is running better. Also no bill all covered under warranty......

Tomorrow morning it goes in to get the exhaust dualled out after the cats.....I can't wait... ....I'll keep you posted on the results.

 

Man did that H2 spend some time at the bottom of the gulf of mexico or something? Glad your being covered under warranty sucks your having so many issues with the same vehicle.

 

im having that problem only during the winter you having a problem with the factory alarm i have the viper alarm and i was told that that created an issue with the factory alarm

 

Big_A
did that fix the problem?