2004 Tahoe/Epic failure

[freeman987]

Ive been tasked with a 2004 tahoe z71. Now a couple of hands have already tried fixing this issue and from what i have gathered have made it worse. 1st there was a blown fuse to the fuel pump. That was replaced and then 2nd the starter started "dragging" so the starter was removed and reinstalled and then 3rd. When went to start the vehicle the cigarette lighter started smoking and smoke came from under the dash. So the center console and center storage area of the dash was removed and the wires that could be found melted were replaced. When went to be started all the bells and whistles came on but no crank...this is were I'm brought in. I checked the wiring on the cig port. Found a spot or 2 slightly melted that was missed so I replaced the whole runs up to the first Delphi plug that sits under the center console. Now this was supposed to be all I was needed for so I didn't get crazy with it. Went to start the vehicle and all the bells and whistles came on but still no start. Checked the 15a fuse under hood and it's blown. Replaced it and popped again. Obd2 isn't working either. Spent a day diving into it and haven't found any melted wires. At this point I said sorry I couldn't help I got other priorities. Few weeks went by and I've been called back up. I have a few days to spare. We'll another guy came in and the entire dash is out and everything that has a connecter is unplugged. I'm plugging everything back in and gonna start from the beginning. I'm. Not big on electrical in vehicles and want to help get this tahoe back on the road. What are my order of operations and what can I do to troubleshoot and diag this issue. Sorry for the backstory but figured it might help. 2004 chevy tahoe z71 4x4 I believe it's a Ltz. Has heated Seats etc. Thank you in advance

 

[TollKeeper]

Unplug that center console harness, and replace the fuse. If it doesnt pop, you know you have it narrowed down. Its all about narrowing the focus of a short, which is done by unplugging a suspected harness, and plugging it in piece by piece until you can narrow it down further.

Its likely a harness end weather pack, or whatever they are called, and it being melted internally

The things I have learned watching SMA

 

[freeman987]

Unplug that center console harness, and replace the fuse. If it doesnt pop, you know you have it narrowed down. Its all about narrowing the focus of a short, which is done by unplugging a suspected harness, and plugging it in piece by piece until you can narrow it down further.

Its likely a harness end weather pack, or whatever they are called, and it being melted internally

I was going to do that with everything unplugged. But worried that could mess up other systems if there is something melted together further down the line. I'm still plugging stuff back in.

 

[rockola1971]

Stick clamp on DC ammeter on Negative wire. Have someone watch it. Plug one thing in at a time and tell the watcher to let you know when the amps all of a sudden jump up on the ammeter. When problem harness is found stick a ohmeter on with battery disconnected and ohm to ground to find which wire is shorted to ground. Find schematic and see what circuit that wire belongs to and inspect every inch of it. Dont be surprised if you are pulling up carpet or seats.

Does it have the Bosch stereo? Hint.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[freeman987]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

Thank you all very much I'll be at the vehicle here shortly and will get pics of the nightmare I'm progress. I believe I've got about all the plugs back together. Besides a few that were connected to the seats which has been removed. I let the battery charge over night so we shall see. I'm gonna go by what you fellas suggest so wish me luck and thank you

 

[mattbta]

Good luck

 

[freeman987]

Good luck

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

Basic 2004 z71. 4x4 ltz i believe. So far center console connection unplugged the climate controls in center dash the GM interface (little black box by comfort controls) 2 of the 5 plugs that have the relays up against the firewall unplugged. Still popping the 15 amp cig fuse

 

[TollKeeper]

Unplug the amp there in the center console. Likely not the issue, but its in the area of burnt wires that you described earlier

It being a 2004, it might have Sirius XM. On my Esky, that was shorted out from a bad factory install. That stopped it from popping the 15a fuse for me.

Also, save a but of money, go to the AutoParts Store, and get a 10a circuit breaker, at least thats what I recommend. Circuit breakers always seem to take a bit more current to pop, so I always go one step below for wiring diags. This way when it pops, you just reset it for the next test.

Also, unplug all the wires under your passenger seat. A PDM, or power seat controller, could be an issue.

EDIT: Check all the wiring going to and from the cigarette lighter, and the OBD port hot wire. They are connected.

 

[03catburban]

being it was cranked and lighter area started smoking. Need to check grounds cause starter pulls alot of ampage and with a poor ground it will find whatever path it can and will smoke/ burn wires along the way

 

[freeman987]

Unplug the amp there in the center console. Likely not the issue, but its in the area of burnt wires that you described earlier

It being a 2004, it might have Sirius XM. On my Esky, that was shorted out from a bad factory install. That stopped it from popping the 15a fuse for me.

Also, save a but of money, go to the AutoParts Store, and get a 10a circuit breaker, at least thats what I recommend. Circuit breakers always seem to take a bit more current to pop, so I always go one step below for wiring diags. This way when it pops, you just reset it for the next test.

Also, unplug all the wires under your passenger seat. A PDM, or power seat controller, could be an issue.

EDIT: Check all the wiring going to and from the cigarette lighter, and the OBD port hot wire. They are connected.

Circuit breakers a damn good idea. Just went thru 11 15a minis. I got the amp completely unplugged. Am trying to unplug everything closest to the firewall harness. Like I said earlier vehicle electrical isn't my fortay. When I'm using the ohmneter on the 15a cig fuse under the hood I'm getting 171.5 reading and it's jumps to 174ish when I unplug certain plugs. Mind you I'm not plugging any back in. I feel like I should be able to isolate this problem a little better and faster.

And if I were to pull the fuse block and remove the 15a fuse port should that let me turn the vehicle over?

 

[freeman987]

being it was cranked and lighter area started smoking. Need to check grounds cause starter pulls alot of ampage and with a poor ground it will find whatever path it can and will smoke/ burn wires along the way

Ahh f me..they did say the starter was dragging after the fuel pump fuse was replaced. I know someone got their hands on it and who knows if it was reinstalled right. Guess I'm gonna put the pick and tester away and jack this fkr in up...lame..thank you also. You guys are taking me to school I appreciate the help

 

[03catburban]

Ahh f me..they did say the starter was dragging after the fuel pump fuse was replaced. I know someone got their hands on it and who knows if it was reinstalled right. Guess I'm gonna put the pick and tester away and jack this fkr in up...lame..thank you also. You guys are taking me to school I appreciate the help

Check ur main grounds for corrosion, also a quick dirty test add a temporary ground like a jumper cable clamp to battery to block.

Could also do a voltage drop test on the ground circuit at the battery

 

[freeman987]

Unplug the amp there in the center console. Likely not the issue, but its in the area of burnt wires that you described earlier

It being a 2004, it might have Sirius XM. On my Esky, that was shorted out from a bad factory install. That stopped it from popping the 15a fuse for me.

Also, save a but of money, go to the AutoParts Store, and get a 10a circuit breaker, at least thats what I recommend. Circuit breakers always seem to take a bit more current to pop, so I always go one step below for wiring diags. This way when it pops, you just reset it for the next test.

Also, unplug all the wires under your passenger seat. A PDM, or power seat controller, could be an issue.

EDIT: Check all the wiring going to and from the cigarette lighter, and the OBD port hot wire. They are connected.

I'm getting around 170 to 190 on my ohm read when testing the cig fuse. If I leave the red probe in the cig fuse port I get 190 ohms in the pdm fuse and about half of the rest of the fuses in the driver fuse block. In the 12 way body plug (brwn) I get 90 ohm on one of the ugly brown wires. My question is have I narrowed thus down at all? Smh

 

[Mudsport96]

So is the 15 blowing as soon as you turn the key to accessory? Or only when you try to start it?

 

[freeman987]

So is the 15 blowing as soon as you turn the key to accessory? Or only when you try to start it?

When I connect the battery

 

[Meathead16]

Circuit breakers a damn good idea. Just went thru 11 15a minis. I got the amp completely unplugged. Am trying to unplug everything closest to the firewall harness. Like I said earlier vehicle electrical isn't my fortay. When I'm using the ohmneter on the 15a cig fuse under the hood I'm getting 171.5 reading and it's jumps to 174ish when I unplug certain plugs. Mind you I'm not plugging any back in. I feel like I should be able to isolate this problem a little better and faster.

Do you have the battery disconnected when taking your resistance readings? While actual resistance can offer some guidance in a way, you're moreso looking for continuity.

And if I were to pull the fuse block and remove the 15a fuse port should that let me turn the vehicle over?

Sounds like you might have something deeper going on. A blown cig lighter/obd2 port fuse won't cause a no start condition.

 

[RoyBoy]

When I connect the battery

Buy a blue point YA809 short an open circuit locator. Just follow the directions and it will take you right to a dead short. For anybody out there dealing with electrical problems or not this is a must for your toolbox. It will pay for itself first time you use it good luck let us know what you find.

 

[freeman987]

Do you have the battery disconnected when taking your resistance readings? While actual resistance can offer some guidance in a way, you're moreso looking for continuity.



Sounds like you might have something deeper going on. A blown cig lighter/obd2 port fuse won't cause a no start condition.

I've been doing all this with the battery disconnected. Besides when I was swapping the 15 amp fuses. With battery disconnected I've been putting my ohm meter on the 15a fuse port with the Red lead and using the negative lead to probe every wire I can. Interesting readings. I know .5 or so is a good reading. With all bells and whistles coming on including aftermarket pro install stereo. (I know it could be done wrong). And a no start. I've got just about everything disconnected..I think.lol..what should my ohm meter read wi th just the cig fuse tested with no battery? Oh and I removed the starter because it was jankied with just before this happened. I'm going into the headliner now. Would this be easier to replace the whole harness?

 

[Meathead16]

I'm confused on what exactly you're trying to do. You're measuring the resistance between the power side of the 15a cig lighter fuse and every wire on the vehicle? Power side of that fuse is fed right from the battery so you're basically measuring the resistance between the pos bat term and everything else which won't be of much help with this problem specifically. If testing from the fused side of the fuse you should only be showing a reading on what that fuse supplies, the cig lighter and obd port. A reading anywhere else is indicative of exposed wires touching.

I forget if it's been mentioned or not but have you removed the underhood fuse box and checked underneath? It's a spot loved by rodents and pests for nests, oh my!

IOh and I removed the starter because it was jankied with just before this happened. I'm going into the headliner now. Would this be easier to replace the whole harness?

If everything was copacetic before the starter was jankied with then most likely the starter, or something closely associated with it, needs a fine tooth comb treatment.