My 2010 Alpha has now been at the dealer for a week and still won't start. Here is the series of events/details:

2010 H3T Alpha with only 50k miles (posting here since the H3T forum isn't very active and it's the same motor/electrical as an H3)

Mods are as follows:
PCM of NC tune via HP Tuners
GM performance catback exhaust
Airdoc intake
Odyssey Extreme battery

Timeline:
Winter 2016-2017: Runs rough after cold start. Runs fine after a minute or so. Issue went away in the spring so seems it was temperature related? No idea if it is related to my current issues.

March 2017 - First time it would not start. Randomly started after trying/waiting for 30 minutes.

March-April 2017 - On my commute the next week, TCS and Stability both failed while I was driving. The truck still ran fine until I got to work. After I shut it off, it would not start. After work, it started right up. I think this happened 1-2 more times and now that I think about it, it seemed to only happen on cold wet days. The cab has never been wet and I have never driven through water deeper than the factory rating. Maybe humidity issues?

I then had PCM of NC disable Passlock. Both the no-start issue and the TCS/Stability failure issues went away.

June 2017 - Truck does not start, then randomly lets me start it 2 hours later. After some research, I replace the starter relay and the ignition switch.

July 2017 - Weird issue where the truck won't crank on first turn of the key, but it will on the second attempt. This seems to happen every other time I drive it, but I figure it is an issue with the new ignition switch and passlock bypass.

August 21st - Truck dies for good and won't start for anything. I have it towed to the dealer. I reset to factory tune with Passlock enabled for the dealer to troubleshoot.

August 22nd - The truck won't let the dealer take it out of park to move it.
Then it randomly lets them put it in neutral. When they connect to it, it won't let them connect to the throttle body. Then it begins to keep failing after connection is initialized. They finally determine the BCM is probably bad, and must wait until Friday for new one to arrive.

August 25th - New BCM is installed, but battery is flat dead. Weird! They charge the battery and are able to connect to learn my keys with the new ignition switch. Then it will crank once and stops. A second crank attempt does nothing. Repeating the key learn process yields the same outcome; one crank, then no cranking.

At this point myself and the dealer are at a loss. As far as I know, it isn't throwing any engine codes so nothing obvious like bad cam position sensor or throttle body sensor. I am aware of a known TSB for the throttle body, but I am not sure if it would cause these issues. Any ideas? Has anyone else dealt with issues like this before? I'd like to reach out to other communities to increase my chances of finding a solution, what other GM vehicles are electrically most similar to the H3/H3T Alphas? V8 Colorado/Canyon? Thanks in advance!

 

Wow!
I feel for ya....

Have the battery terminal been cleaned? Changed connectors?
Cleaned sun roof drain tubes if applicable? Carpet wet on passenger side?
Ground wires removed one at a time cleaned, checked for continuity and reattached?
Have you checked the ground for starter? Have you checked to make certain you don't have a dead spot in starter? Have you made certain that none of the connectors at the pcm are bent or corroded, missing?
Also, there with corrosion in some of the main connectors in harness and in fuse box?

 

Thanks for the reply, you really jogged my memory. No sunroof, but about a year ago a water bottle exploded in the passenger footwell and it had to be dried for a day. I am not sure how long it was wet like that before I discovered it. I wonder if that caused the BCM to go bad and possibly corroded some wires. I just told the dealer and they are checking out that area/harness today.

The battery terminals were replaced with new ones when I installed the Odyssey Extreme battery last winter.

The starter switch wire isn't getting voltage when the key is turned, so the drop is happening before the starter.

Thanks again for the ideas, I really appreciate it.

 

Is it possible that there is corrosion in the lower half of the fuse box or a faulty main fusible link?

 

A rodent chewed on the wiring?

 

Bad replacement ignition switch. Might also be a bad starter relay. Electronic parts are man made, even new ones have failure rates.

You should have replaced only the ignition switch, then the starter relay after you confirmed whether the ignition switch changed the problem or did nothing. When you do 2 or more electronic changes at once, you do not know which one to point the finger at when something doesn't work.

Good luck.

 

I should have specified that the starter relay and ignition switch were replaced about 3 weeks apart. The issue happened so infrequently before last week that it was pretty much impossible to troubleshoot until now.

Quick update, the new BCM was found to be bad from the factory. Another new BCM shows up tomorrow so we'll see if that fixes the issue.

They checked for corrosion and wiring damage and didn't see anything obvious. A small part of me wonders if there is a wiring issue that maybe fried the first two BCMs. I really hope not, but I know crazier things have been known to happen...

Thanks again for all of the ideas.