Got a Hummer...Won't Start

JPaul · Sep 22, 2020

I've torn apart the switch before to figure out just how it is failing. There really isn't an easy way to test it without proper equipment and expertise and more time than I would care to spend. It's less work to just swap the switch out since it's been pretty well established that it is the main source of this problem, and not just by the H3 guys. Lots of other GM vehicles that use the same Passlock system tend to have this very problem. You will be a lot happier with that new switch.

Sent from my SM-N975U using Tapatalk

cgalpha08 · Sep 23, 2020

I had PCM of NC tune out the passlock. Not sure what happens then when the switch fails and you dont have the pass lock programmed in there?

I get that its a security thing but as its not my daily i'm ok with that.

720H · Sep 23, 2020

fowlken8 whats the details on your rig looks pretty jacked

fowlken8 · Sep 23, 2020

It's got a lift, volant cold air intake, throttle body spacer, 35" mud tires, 20 inch rims, exhaust, pioneer touchscreen sound system with sub and amp, roof rack with overkill lights. It's an 07 with 130k miles, but I got a very good deal on it.

fowlken8 · Sep 25, 2020

I replaced the sensor... No more lock 1 error..... Drove perfectly for a couple of days. Still having an unpredictable hard start at times. Most times it turns over first try, other random times, 5th...10th try. Hmm. I've realized that I don't always hear the fuel pump turn on, and when I do it stays amazingly fast. Maybe a bad fuel pump?

I replaced it twice on my old 07.

alrock · Sep 26, 2020

If the engine is turning, it's not likely the fuel pump. You may have a failing battery. In AZ they don't necessarily wear out; they break and go from working to not working instantly. Have you had the battery tested? I think you said you checked the cables and terminals but perhaps put a tester on those cables. They could be corroded and weak internally.

Jeepwalker · Sep 26, 2020

I just articulated in a separate post how my pick-up truck (not H3) battery died a couple weeks ago. I had driven it all day to pick up construction supplies at various places around town. Went to jobsite and worked the whole day till night. Then no-start. Got a lot of funky warnings and messages on the LCD dash display (again, not H3). After charging the battery for hours it spectacularly failed a load test. Needle dropped like a rock. New battery and boom! She's all good now. So, you never know. A Harbor Freight load tester might be something to add to your kit, or take the battery to an auto parts store for a check.

fowlken8 · Sep 29, 2020

Should I hear the fuel pump prime reach time I cycle the ignition off and on? Because I don't. I hear it the first time I start it each day and that's it.

I just replaced the pcv hose, mine was smashed flat and cracked up. We'll see if it helped. I'll take a look at my spark plugs soon

alrock · Sep 29, 2020

I don't really listen for the fuel pump on the H3, but I can tell you that on my Silverado it only primes if the truck has been sitting for an extended period, like overnight.

fowlken8 · Sep 30, 2020

alrock said:
I don't really listen for the fuel pump on the H3, but I can tell you that on my Silverado it only primes if the truck has been sitting for an extended period, like overnight.

That's exactly what I wanted to hear. I only hear it after sitting overnight. I too, never pay attention.

I replaced the ignition switch and no longer get the lock 1 error code (so far). It'll start every time, sometimes a LONG crank.

The battery is new. The connections look perfect. I don't know where all of the grounds are at so I haven't checked them. The fuse box looks fine too. All connections and fuses/relays are in place with no corrosion.

I wonder if the PCV hose could have any negative effects? I definitely needed one and replaced it. Could that fix an idle issue?

Happy Hummer · Dec 4, 2020

Time to stop guessing and start inspecting.
Back probe for dc V+ and ground. Continuity tests and ohms values.
I'd start by verifying that I'm receiving solid ground and 12V+ to chassis and engine/starter. Remove them, clean and reinstall.
I'd take the time to probe for 12V+ and ground at the fuel pump. Nothing like corrosion in your connector to ruin the day.

650Hawk · Dec 7, 2020

Although the battery cable clamps may LOOK perfect, if they are the stock POS clamps, get rid of them and replace with some nice clamps, like This:

Trust me, the stock clamps are the cause of many, many electrical issues with the H3.

Got a Hummer...Won't Start

JPaul

Well-Known Member

cgalpha08

"Like Nothing Else"

720H

Active Member

fowlken8

Well-Known Member

fowlken8

Well-Known Member

alrock

El Diablo

Jeepwalker

Well-Known Member

fowlken8

Well-Known Member

alrock

El Diablo

fowlken8

Well-Known Member

Happy Hummer

Well-Known Member

650Hawk

Well-Known Member