2010 Manual 5 Speed, 107k miles,

Noticed this weekend when I went to start the truck it didnt. I had put the key in, pushed in clutch, turned the key, and the dash flashed and nothing happens. No crank no sputter, just nothing. Let clutch out and put back in, same thing. Turned key all the way back to off and then pushed in clutch and turned key same exact time and it starts. It starts every time after this even if I do it the slow way. Seems to only be a problem if it sits for a half hour or so. Tested it again tonight seems to be the same deal. I have a new battery so I dont think its that.

Starter motor doesn't seem to be struggling, only takes a few turns ( 1 2 3 boom) and we turn over.

My first thought was the truck is older, so maybe gotta wait for the fuel pump to build some pressure
I did notice when I try from cold and turn the key and wait the fuel pump sounds a little sad (not sure how it usually sounds) ... but if it was a fuel pump problem I feel like it wouldnt start at all or would run like ****, OR take a lot of turns to turn over, but its starts real quick when it wants to

The 2nd try/ doing all the steps at once seems to work well, just odd. Was wondering if it could be the clutch safety sensor going bad? But then letting clutch out and going back in should work, unless that sensor latches a fault once ignition is on.

Anyone got any ideas?

 

Have you performed the first mod to be done to every H3/H3T? In other words, are you still using the crappy azzed OEM Battery Terminal Connectors? If so, hack them off and replace with a quality aftermarket set like Stingers or your favorite brand.

What is the resting voltage of your battery?

If you suspect the clutch safety switch, disconnect it and clean both the switch and harness side connection with CRC electronics cleaner. Do the same thing with your ignition switch. The CRC E Cleaner should be standard garage equipment for anybody with vehicle/equipment more than a few years old.

Photo below courtesy of hummerz.

 

Today went to start it, no dice, tried the everything at once trick, nothing..

Not turnover, no click, first thought was maybe the battery is low and the alternator didn't charge it last time I drove. Voltimeter I have reads off the cars dc plug, said 12.2, so a little low, tried to jump it for a while. Let it get up to 12.9, nothing. dash shuts off briefly when I try and nothing happens. Checked battery out, it had some corrosion, so maybe battery cable is no good. All other accessories in the car turn on, air, radio, lights, clock hasn't been lost.

Tried cleaning the contacts and jumping again, I don't get anything.

Is this a starter problem now? I feel like if it was battery cable I wouldn't be getting any power anywhere. Starter wasn't struggling last night.(click click boom). I'm starting to think starter solenoid isn't getting any power?

 

also doc didnt get to try to clean the contacts on the ignition housing like you said, because I wasnt sure where to start? Is it just the two screws on the plastic underneath and then I can disconnect a plug and spray? or do I need to pull the whole thing out and disassemble? The key barrel itself doesnt seem bad, I dont feel any resistance or binding when I try to turn it. is that also a spray of crc down into the barrel then insert the key and jiggle?, or is that a wd 40 job?

also also, terminals have not been replaced far as I know, nothing loose and havent lost power yet so I dont think its them but hey anything possible

finally, where is the clutch safety switch, anyone got a diagram or video on that? I havent had much specific luck searching the web.

 

Your analysis is flawed. Having sufficient power to start is an entirely different animal than seeing some lights and the radio turn on. The failure rate of the OEM Battery Terminals is about 95-100%.

Instead of looking on the internet for your clutch switch, take a look under the dash at the clutch pedal arm where it connects to the firewall.

WD40 is garbage, not a lubricant, but a solvent. I do not own any, no use for it.

The ignition switch is a to screw and do. Scale of 1-10, 10 being most complicated with special tools, about a 1.5. There are vids posted here an on the web for the "H3 Hummer Ignition Switch".

Take a look at this thread........... Ignition Problems

 

Sounds like the neutral safety switch on the clutch pedal bracket.
Follow the clutch pedal up under the dash.
Look @ the pix below. I would first wiggle the wires and see if it will start while wiggling.
Clutch Pedal Position Switch - GM (15101582)

 

Doc, if the terminals were bad wouldn't I not see power anywhere or could they be just **** enough to prevent me from starting?

 

It takes 12.4-12.8+ Volts to start. Dash lights etc..... can illuminate with voltage much lower, even in the upper 11 something range. A car battery is not like a gas tank, when resting voltage is 12.3V it is DEAD. Even a tiny bit of voltage loss is important.

Now, think about a fully charged battery only half azzed connected to the vehicle.............. see the issue?????

 

Ended up giving up and getting a tow as it was cheapo by me since the shop was less than 5 miles away, turned out it was the starter relay guys,

relay wasn't much fortunately

But thanks for all the help!

 

That was easy and should always be the first thing to do when checking for a failed circuit.
GO TO THE UHFB & CHECK FUSES /RELAYS!
If you researched this site you would have seen numerous posts from me advising to SWAP RELAYS to check results. In your case simply swapping #78 with #88 would have solved your issue. Hope your a$$ doesn't hurt. Live & Learn.