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Help ! Arch When Removing Relay From Battery

2500HD 8.1

By 2500HD 8.1
in Ask A GM Technician

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2500HD 8.1 Enthusiast

2500HD 8.1

Posted
Posted

On my 2005 Yukon Denail, while I was disconnecting a headlight relay from the auxiliary battery terminal (the little red box near the alternator), I completely forgot to disconnect the battery (duh), and my ratchet arched on the alternator mount.

 

Now the car dies out immediately after starting, the headlights dont work, and the keyless entry doesnt work. I'm sure pretty much the whole electrical system, but those are the things that I have discovered so far. I'm hoping that a fuse blew, and not the PCM or something else major.

 

Any suggestions? Any specific fuses to check. I have checked some of them. How can you tell if the larger ones are blown?

 

Hopefully I dont have to tow it to the dealer.

wct Enthusiast

wct

Posted
Posted
On my 2005 Yukon Denail, while I was disconnecting a headlight relay from the auxiliary battery terminal (the little red box near the alternator), I completely forgot to disconnect the battery (duh), and my ratchet arched on the alternator mount.

 

Now the car dies out immediately after starting, the headlights dont work, and the keyless entry doesnt work. I'm sure pretty much the whole electrical system, but those are the things that I have discovered so far. I'm hoping that a fuse blew, and not the PCM or something else major.

 

Any suggestions? Any specific fuses to check. I have checked some of them. How can you tell if the larger ones are blown?

 

Hopefully I dont have to tow it to the dealer.

 

 

 

Ok first of all that's a bummer, I would grab a test light and start checking all of your under hood fuses. Place your test light to ground then start checking both sides of the fuses it should light up on both sides of the terminals. I would check the big mega fuse in the front of the fuse box that has two posts sticking out should be like 125amp or so. if you want you could also place an ohm meter across the fuses when removed if you have an open fuse it should read OL. on the j case fuse(the larger ones) you should be able to see in there and see if they are blown.

 

I hope this helps you and prevents you having to tow it in if not reply back!

wct Enthusiast

wct

Posted
Posted

you may also want to check for voltage @ the back of your generator at the big post see if you light powers up. if not there may be a fusible link in line from the junction block to the generator. should be a black cable. if you could it would help if you could post the last 8 digits of your vin to see what options this ride has.

2500HD 8.1 Enthusiast

2500HD 8.1

Posted
  • Author
Posted
you may also want to check for voltage @ the back of your generator at the big post see if you light powers up. if not there may be a fusible link in line from the junction block to the generator. should be a black cable. if you could it would help if you could post the last 8 digits of your vin to see what options this ride has.

 

 

The last 8 of my VIN are 5J118831. I checked pretty much all of the fuses that I would think. I do have an 04 Avalanche that I'm making some comparisons, but no luck so far. I'm going to the parts store to test my alternator. A friend said that I could have blown a dial in the alternator? The fusable link between the red box and the alternator looks good.

 

I'll check a few more things.

 

What is the relay or black box attached to the negative battery cable? My 04 Avalanche does not have that. Just some numbers and GM Made in Mexico on it.

 

Update......No luck with anything!!!!

wct Enthusiast

wct

Posted
Posted

the black box that i think that you are talking about should fit over the battery cable and fasten to it is a generator battery control module and talks to the pcm to tell the alt to charge or not it is new for 05 and up. that's why your 04 doesn't have it it. is power from the RVC fuse in the underhood fuse box. I assume that you have power @ the generator right? if you do then your fusible link should be good, Did you get a chance to check the big mega fuse yet? you may have to pull the cover off of the fuse box to access it you might have to pull the brace off from the cowl to the fender 4 13mm bolts to remove the black cover off the fuse box. I'll do some more checking and check back in shortly.

wct Enthusiast

wct

Posted
Posted

you may also want to check the fuses in the ip fuse box on the left had of your ipc open you left door and check all those fuses make sure to check ign 0 and any fuses that has ign in front of it such as ign1 I'm almost certain that your generator is OK your looking at a blown fuse some were. your generator dosen't really have any part of providing power to your fuse box and such as long as you have b+ at the back of it it should be OK. I guess what I'm trying to say is that it shouldn't have any effect on it not starting and keep running your battery should be able to provide voltage to keep it running. I'm not sure if that makes sense. your Yukon will start and run until your battery loses it reserve then it will die and your battery will be dead in the mean time you should have some sort of warning that batt is not charging.

2500HD 8.1 Enthusiast

2500HD 8.1

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I was not able to get the alternator checked because the crappy parts store couldnt check it for various reasons.

 

All the fuses and relays that I can find are good.

 

Thanks guys for the help. I'm still trying.

 

Update........still no fix......I see where the mega fuse should be according to the fuse box cover, but I cant locate it. I have a friend with me now who knows a ton more than I do, and we cant find the 125 fuse????

 

Im giving up......gonna tow it to the dealer tomorrow.

bill190 Enthusiast

bill190

Posted
Posted

Try one more thing. These newer vehicles have all sorts of computers, networks, etc. So....

 

Try rebooting!

 

Remove power from the battery for about 10 minutes (disconnect negative battery terminal). Then reconnect.

kdm101 Enthusiast

kdm101

Posted
Posted
Update........still no fix......I see where the mega fuse should be according to the fuse box cover, but I cant locate it. I have a friend with me now who knows a ton more than I do, and we cant find the 125 fuse????

 

Im giving up......gonna tow it to the dealer tomorrow.

 

The mega fuse is only for a diesel vehicle. It's for the glow plugs.

2500HD 8.1 Enthusiast

2500HD 8.1

Posted
  • Author
Posted

Thanks guys. Yep no mega fuse. Battery disconnect/reboot didnt work. Its weird, I'm thinking I fried a computer or it has something to do with the security/theft deterrent system. The fuse box has power from the battery and no blown fuses or relays (that I could find).

 

The radio, power windows, and power door locks are the only things that dont work (other than the vehicle dying out). Hopefully I'll find out tomorrow from the dealer.

brims Senior Enthusiast

brims

Posted
Posted

Anyone else notice the double posting? You really shouldn't be posting the same question twice and keep them both running. Maybe a mod can merge the 2 and close/lock 1 of them.

TexasAl Enthusiast

TexasAl

Posted
Posted

Swap the starter relay and the alternator relay , with other similar relay to see if they are still working. This happened to me a few years ago, and it turned out to be the fusible link that goes from the starter to the alternator. Make sure you follow the cable carefully, and maybe you can find the problem. Good luck. Be sure to let us know what happens.

 

Al

2500HD 8.1 Enthusiast

2500HD 8.1

Posted
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I ran outta time today, so its going to the dealer tomorrow. I will report back. I have at least 5 friends that gave suggestions also that are curious too.

 

Thanks guys.

2500HD 8.1 Enthusiast

2500HD 8.1

Posted
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Update...I'm pretty surprised. The dealer said that my factory XM module/box was shot!!! Probably unrelated to my mistake with the arching ratchet, or maybe it was. Since the XM module connects with all the other modules, it caused the problems. At least thats what the dealer said. They pulled the old one and ordered a new module. Truck runs just fine.

 

Thanks for all the help. I never would have guessed!!!

TexasAl Enthusiast

TexasAl

Posted
Posted

That's strange. I doubt that the XM module would cause your truck not to work correctly. Let us know what happens.

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