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H3 Ignition Circuit Fail - H3 Alpha


Well-Known Member
Peru, IL
Don't know if any of you have run into this, but thought this post might be helpful.

On a few occasions the past two winters, my H3 completely refused to engage the starter circuit. Occurred months apart. Learned a few things:
1) I replaced the battery twice; first time not a waste, battery was weak. Second time not a total waste, since I upgraded to an Odyssey, but, in hindsight, probably wasn't the issue
2) If you try to buy a replacement for any of the Omron relays in your truck, you'll be annoyed. Nobody seems to sell them new or clearly state what the equivalent alternative is. If you go to the parts store and try to buy the run, crank or run, start relay for an H3 Alpha, their notes will tell you that the relay is only for the 5 cylinder. Not a crisis - the relays are identical, so you can try to buy one of the other relays. However, I have not yet actually confirmed that anyone does sell the alternative to the Omron relays that are in our trucks and in many other GM vehicles.
3) Pretty sure my problem was just dirty connections at the relay. Frustrating, because I did a bunch of other stuff (and once again broke the plastic fuse box cover, as it was very cold out when my truck failed to start).

It's been a few weeks since I swapped two relays in the box, effectively just cleaning their connections. Haven't seen a repeat of the issue. Pretty sure the problem was just corrosion on the relay connections.

So, if you turn the key on your H3 Alpha and nothing happens, but all of your electrical stuff is working fine and battery seems OK, step one is to swap the start relay with another relay and clean the connections. Might be a free fix to the problem.

Although, having an excuse to upgrade to an Odyssey battery is not a terrible thing either ...


Well-Known Member
High Desert & Santa Maria
I had a similar problem over a year or two ago. I managed to get a couple of relays at my local dealer and I also found some on the rack at Autozone. It's probably not a bad idea to mark and identify relays when you start shifting them around. Keep a couple in your glove box or console.