Loss of electrical power when turning the key; 2002 Z71 Tahoe

[Ec031299]

This has been an intermittent issue. I have a brand new battery, the grounds have good connection, the main ground strap is in great shape. What happens is I will get in the car, usually after starting it a few times within an hour or two, and the security light on the dash will flash like normal, all gauge and cluster lights come on like normal when the key is turned to accessory and then when I attempt to turn it over, I hear one click and lose all electrical power. When I attempt to start again, the same thing might or might not occur depending if the cluster is getting power or not. I don’t think it would be a fuse or relay because the car starts great for weeks at a time. Not sure the starter os the issue because I lose all electrical power to the entire vehicle when this occurs. Maybe there is corrosion on the positive cable somewhere I haven’t found? I’ll be able to check that out later after I get home. Maybe ignition switch?

 

[clandr1]

I would have your battery and alternator tested first, just to check the easy boxes before diving in to more complex problem solving.

Assuming your battery and alternator are good, it may be a loose cable connection problem. My wife's previous car, a Jeep GC, had this same thing happen on occasion and we tracked it down to loose cable clamps for the positive and negative wires on top of the battery. I would remove, clean, and re-install (taking care to tighten to spec) all your positive and negative battery cables that go from the battery to another location (ground, starter, etc.).

If this doesn't work, I would next look at the starter as the culprit. Next time this happens, after taking the steps above, try lightly tapping the starter with a rubber mallet or hammer and see if it fires up. If so, you need a new starter.

Please keep us posted with what you find out!

 

[MassHoe04]

Can you confirm "all" power is lost when this happens?

I have an occasional issue, that I was originally thinking was being caused by a failing pass-lock sensor on the ignition. At first I thought Everything was dead, but I found the radio came on and stayed on after the door opened and interior lights came on when the door opened and stayed on after the door was closed. I think I am narrowing down my issue to be related to switch inside the door latch doing its thing most of the time, but not all the time.

Do you actually have 100% loss of power to all systems? Door locks, lights, radio, seats, etc.? Nothing?
Just trying to help get more information on your situation.

 

[Ec031299]

I would have your battery and alternator tested first, just to check the easy boxes before diving in to more complex problem solving.

Assuming your battery and alternator are good, it may be a loose cable connection problem. My wife's previous car, a Jeep GC, had this same thing happen on occasion and we tracked it down to loose cable clamps for the positive and negative wires on top of the battery. I would remove, clean, and re-install (taking care to tighten to spec) all your positive and negative battery cables that go from the battery to another location (ground, starter, etc.).

If this doesn't work, I would next look at the starter as the culprit. Next time this happens, after taking the steps above, try lightly tapping the starter with a rubber mallet or hammer and see if it fires up. If so, you need a new starter.

Please keep us posted with what you find out!

Thanks for the reply.
Today I checked the battery cables and there aren’t any signs of corrosion maybe other than the smallest amount of dirt on contact surfaces. I cleaned the grounds coming off the negative cable real well, there were several of them on the frame. I am fortunate to have a 2 post lift in my shop so this wasn’t too much of a back breaker. I also cleaned off the positive connections in the little red accessory box. It fired right up so maybe that was it‍. As I said all the connections weren’t very dirty. The ground near the starter was nice and tight as well. I know some people have said just disconnecting the negative and reattaching it will temporarily fix the problem so we will see what happens. With the front dif. and axels coming out, the starter is almost impossible to access without a decent amount of effort removing some things in the way.

 

[Ec031299]

Can you confirm "all" power is lost when this happens?

I have an occasional issue, that I was originally thinking was being caused by a failing pass-lock sensor on the ignition. At first I thought Everything was dead, but I found the radio came on and stayed on after the door opened and interior lights came on when the door opened and stayed on after the door was closed. I think I am narrowing down my issue to be related to switch inside the door latch doing its thing most of the time, but not all the time.

Do you actually have 100% loss of power to all systems? Door locks, lights, radio, seats, etc.? Nothing?
Just trying to help get more information on your situation.

Thanks for your help. As far as I could tell, everything was without power when this happened. When I went out to take a look this morning, there was no power when I opened the door at all so I am hoping really cleaning up all the connections was the issue. This has always been a California Tahoe so there isn’t any corrosion on the frame or in the engine compartment. Has to be some grounding issue if the whole system lost power when trying to turn the engine over. Everything seems to be working fine now, time will tell…

 

[clandr1]

Thanks for the reply.
Today I checked the battery cables and there aren’t any signs of corrosion maybe other than the smallest amount of dirt on contact surfaces. I cleaned the grounds coming off the negative cable real well, there were several of them on the frame. I am fortunate to have a 2 post lift in my shop so this wasn’t too much of a back breaker. I also cleaned off the positive connections in the little red accessory box. It fired right up so maybe that was it‍. As I said all the connections weren’t very dirty. The ground near the starter was nice and tight as well. I know some people have said just disconnecting the negative and reattaching it will temporarily fix the problem so we will see what happens. With the front dif. and axels coming out, the starter is almost impossible to access without a decent amount of effort removing some things in the way.

Good steps, and here's hoping it fixes the problem.

Random questions: are you using the factory side mount battery connections, or are you using top post battery clamps?

 

[Ec031299]

Good steps, and here's hoping it fixes the problem.

Random questions: are you using the factory side mount battery connections, or are you using top post battery clamps?

I still have the factory side mount connections. The positive side being so close to the fuse box makes it a test of dexterity at times to get it hooked back up. Did you convert to top mount?

 

[clandr1]

I still have the factory side mount connections. The positive side being so close to the fuse box makes it a test of dexterity at times to get it hooked back up. Did you convert to top mount?

Yes it does! No, I haven't, but the issues I've experienced (my wife's Jeep and, just yesterday, my friend's 2013 GMC Yukon Denali) were both top post clamp mounts that were causing the issues.

Given that you've eliminated battery connection issues, I'm thinking one of the following scenarios applies given you say you only experience this issue after starting the truck multiple times in a short period:

1. Your battery is running down too quickly which means either your alternator isn't fully charging or your battery is defective
2. Your starter is failing and needs to be replaced

 

[Ec031299]

Yes it does! No, I haven't, but the issues I've experienced (my wife's Jeep and, just yesterday, my friend's 2013 GMC Yukon Denali) were both top post clamp mounts that were causing the issues.

Given that you've eliminated battery connection issues, I'm thinking one of the following scenarios applies given you say you only experience this issue after starting the truck multiple times in a short period:

1. Your battery is running down too quickly which means either your alternator isn't fully charging or your battery is defective
2. Your starter is failing and needs to be replaced

I’d like to think it isn’t the battery as I put a new one in a few weeks ago thinking this was just due to a dead battery. As far as it getting drained too quickly, I’m hesitant to think that might be the case as I started it twice the other day and the third time I tried the car didn’t start. Then, after sitting for almost 2 days, and after me cleaning up all the connections, it fired right up with plenty of cranking power.

The first time this happened, I left the key in the accessory setting, with no electrical power to be clear, and I could hear sort of a sizzling noise inside the dash somewhere. Again this was happening with no power anywhere else in the car which would hopefully just mean one of the grounds was not clean enough or tight enough. When the engine is running it I usually show 14+ volts, usually a little more when I start up cold. I’m not sure if a faulty alternator would cause these issues if I appear to be running at a good voltage and nothing seems to dim while driving. I’ll update if it occurs again and what I try next, alternator or starter. Hopefully I don’t need to!
Thanks again