2012 Tahoe 5.3 Shut down 3 months. Will not start. Help? Ideas? FIXED!

[TerryKing]

THANKS FLESS and WES! OK I will be on it again in the morning... I need to get the spare tire down and then move truck out and open my pit and move it back. THEN I can get at all that... Wow..

This'd Almost Be Fun in the Summertime.... Regards, Terry

 

[TerryKing]

FOUND Something: Going over the Fuel System Control Module tests in the link @Fless sent, before dropping the Spare Tire, AND:

SWAG: Check power on both sides of fuse #21 for the Fuel System Control Module.

So I tried to lift fuse #21 a little so I could probe it. Seems stuck. Use needle-nose pliers.. stuck. Rock it a little and it came apart!!!

I have the top half of the fuse and it looks corroded. The PINS are still in the electrical block. I will go out this morning and try to carefully pull those pins out. I have good Contact spray and will use that first.

Any pointers on handling this kind of broken fuse appreciated!!

@Fless THANKS for your Scientific Guess! It may have pointed to a/the problem.

Regards, Terry

 

[Fless]

Hopefully you can get those fuse legs out without damage. I don't have any good tips for that.

The regular fuses can be tested in-circuit using the test points that are on each fuse, but that won't necessarily test for damaged legs or full circuit continuity.

Hoping for an easy fix!

 

[TerryKing]

@Fless THANKS! I didn't ever notice those test points. Makes a lot of sense. Putting my head-mount magnifier on 82 year old eyes, I see those!

--- LEARNING ---
Regards Terry (Back after another priority job...)

 

[TerryKing]

@Fless THANKS! I didn't ever notice those test points. Makes a lot of sense. Putting my head-mount magnifier on 82 year old eyes, I see those!

--- LEARNING ---
Regards Terry (Back after another priority job...)

Wow do I HAVE to quote myself?? Sigh...

MAIN GOOD NEWS and a large WHAT TO DO???
Tried to extricate the broken fuse pins with several tools/probes etc. No luck. I was worried about breaking the pin stubs off altogether. So I 'connected' a clip lead between the two points.

Seat belt on, Key on.. FUEL PRESSURE right up to 45 PSI. Crank and immediate START/RUN! After 30 seconds the clip lead looked hot and I shut it down. The fuel pressure stayed high for a while after shut down and key removed.

WHAT TO DO??

- LONG TERM I don't feel I can trust the fuse socket . I need to find the two wires (One from Engine Control, one from Fuel System Control Module, right??) externally add a fuse holder and 25A fuse. Does anyone have access to the wiring diagrams and color codes??

- TEMPORARY: Maybe a Situation Horribleus I have used in a couple of corroded-contact emergencies in the past (Like my home power pole circuit breaker contacts with the electric meter bus. Don't Ask!). Vermont Winters are not friendly to contacts. SO:
- Inline "weatherproof" fuse holder with 3 inch leads of about #12 copper stranded wire.
- 25 Amp fuse to fit holder
- Two small ring-shank bronze nails with fuseholder wires wrapped and soldered to the top end of the nails.
- Carefully hammer the nails into the two original fuseholder sockets, same depth as a real fuse would go. At least it's not 120VAC
- Insert fuse.
- Cross fingers and other appropriate incantations. Key in, ON and START ! ? ! ?

Many THANKS to @Fless and @Wes and others fir helping me track this one down... !!

Couple photos follow. Any wire color code / info, pointers appreciated!

Regards, Terry

 

[iamdub]

Wow do I HAVE to quote myself?? Sigh...

MAIN GOOD NEWS and a large WHAT TO DO???
Tried to extricate the broken fuse pins with several tools/probes etc. No luck. I was worried about breaking the pin stubs off altogether. So I 'connected' a clip lead between the two points.

Seat belt on, Key on.. FUEL PRESSURE right up to 45 PSI. Crank and immediate START/RUN! After 30 seconds the clip lead looked hot and I shut it down. The fuel pressure stayed high for a while after shut down and key removed.

WHAT TO DO??

- LONG TERM I don't feel I can trust the fuse socket . I need to find the two wires (One from Engine Control, one from Fuel System Control Module, right??) externally add a fuse holder and 25A fuse. Does anyone have access to the wiring diagrams and color codes??

- TEMPORARY: Maybe a Situation Horribleus I have used in a couple of corroded-contact emergencies in the past (Like my home power pole circuit breaker contacts with the electric meter bus. Don't Ask!). Vermont Winters are not friendly to contacts. SO:
- Inline "weatherproof" fuse holder with 3 inch leads of about #12 copper stranded wire.
- 25 Amp fuse to fit holder
- Two small ring-shank bronze nails with fuseholder wires wrapped and soldered to the top end of the nails.
- Carefully hammer the nails into the two original fuseholder sockets, same depth as a real fuse would go. At least it's not 120VAC
- Insert fuse.
- Cross fingers and other appropriate incantations. Key in, ON and START ! ? ! ?

Many THANKS to @Fless and @Wes and others fir helping me track this one down... !!

Couple photos follow. Any wire color code / info, pointers appreciated!

View attachment 389180View attachment 389181

Regards, Terry

It looks like that fuse had a bad connection and, being a relatively high-amp circuit, the connection burned and corroded solid.

I believe that whole top panel that holds all the fuses is removable. You could find a good one from a part-out, in person or online, and swap it. Take a clear pic of it and compare it to one from another car.

I know @Doubeleive is familiar with this multi-layer assembly and might can offer more input.

 

[Doubeleive]

Wow do I HAVE to quote myself?? Sigh...

MAIN GOOD NEWS and a large WHAT TO DO???
Tried to extricate the broken fuse pins with several tools/probes etc. No luck. I was worried about breaking the pin stubs off altogether. So I 'connected' a clip lead between the two points.

Seat belt on, Key on.. FUEL PRESSURE right up to 45 PSI. Crank and immediate START/RUN! After 30 seconds the clip lead looked hot and I shut it down. The fuel pressure stayed high for a while after shut down and key removed.

WHAT TO DO??

- LONG TERM I don't feel I can trust the fuse socket . I need to find the two wires (One from Engine Control, one from Fuel System Control Module, right??) externally add a fuse holder and 25A fuse. Does anyone have access to the wiring diagrams and color codes??

- TEMPORARY: Maybe a Situation Horribleus I have used in a couple of corroded-contact emergencies in the past (Like my home power pole circuit breaker contacts with the electric meter bus. Don't Ask!). Vermont Winters are not friendly to contacts. SO:
- Inline "weatherproof" fuse holder with 3 inch leads of about #12 copper stranded wire.
- 25 Amp fuse to fit holder
- Two small ring-shank bronze nails with fuseholder wires wrapped and soldered to the top end of the nails.
- Carefully hammer the nails into the two original fuseholder sockets, same depth as a real fuse would go. At least it's not 120VAC
- Insert fuse.
- Cross fingers and other appropriate incantations. Key in, ON and START ! ? ! ?

Many THANKS to @Fless and @Wes and others fir helping me track this one down... !!

Couple photos follow. Any wire color code / info, pointers appreciated!

View attachment 389180View attachment 389181

Regards, Terry

I would try and find a local junkyard and grab the fuse box top and swap it out, when you pull it up there are sections under the bottom that are clipped in, a flat head screw driver will release the one you need, you might get lucky by pulling the box top out and be to get to it from under neath or patch a replacement fuse holder in. just lift those grey color handles and pull straight up. when you put it back or a replacement back in be sure it is on nice and snug so you don't have any other issues

 

[Doubeleive]

here is a listing for one online if you click thru the photo's you will see what it looks like underneath, on this one the sections on the bottom have been removed already

Fuse Box Panel Junction Relay Block 22798217 OEM GMC Chevy Cadillac 2010 - 2014✅ | eBay

Quality of product and service are our top priority. We aim to exceed expectations and every opportunity. When you are happy, we are too!.

www.ebay.com

 

[TerryKing]

WOW.. More Stuff I Never Knew!

@Doubeleive Do I understand this right??

So, the entire top panel section with all the relays and fuses PLUGS IN to a series of connectors that come from different sections of the engine and body??

So are the fuse sockets and relay sockets part of the removeable top?
IF I unclipped the top panel and the SECTION connector for that upper-right area, I could trace what wires went to that fuse??

Wow. So I am thinking that if I can do a 1/2Ass temporary connection, then in the Spring/Summer I can take this totally apart, get a used replacement top section (With an intact F21) reassemble it and have THAT fuse situation resolved.

I was already thinking that later I should remove, contact clean and replug ALL the Fuses and Relays.

Is There a decent aftermarket manual for these vehicles that would have most of this information?? I've done a lot of GM and Ford work but I'm about 20 years behind.

IT PLUGS IN. Blows my mind. All THOSE connectors should be cleaned next Spring. I Think. 200,000 plus miles on Vermont highways with salt air.. NOW I'm nervous... Should (semi-obviously) disconnect battery before removing that top panel??

Can't thank all you 'guys' enough! Regards, Terry

 

[Fless]

So, the entire top panel section with all the relays and fuses PLUGS IN to a series of connectors that come from different sections of the engine and body??

So are the fuse sockets and relay sockets part of the removeable top?
IF I unclipped the top panel and the SECTION connector for that upper-right area, I could trace what wires went to that fuse??

Yes to those three questions. Each harness block underneath will snap out of the upper part that holds the fuses and relays.

All good suggestions from the forum. You could look on Facebook Marketplace, Next Door, Craigslist, or a local junkyard, etc. for someone parting out a similar truck and see if they would sell the upper part of the underhood electrical center. Just be sure to inspect carefully, maybe pulling out all the fuses and relays and making sure the contacts are solid.

EDIT: you can also look at www.car-part.com, select your vehicle info, Zip code, item desired, and see yards that have your part, the price, and the distance from your Zip.

 

[Joseph Garcia]

Solid answers and explanations to questions, along with recommendations for next steps. That is why this Forum ROCKS!!!

 

[Stshack]

Hi Everyone,
My 2012 Tahoe has run very well for years. Winter starts were OK.

I had to leave it for 3 months to travel to Middle East. I added Stabil, fresh gas before shutdown. Ran battery maintainer. It 'rested' 3 months in my barn in Vermont.

No Start. If cycling key on and off after an hour, it may do a quick stumble. No actual start. Waited for 3 above-freezing days, added some electric heat under fuel lines. No start. Battery good.

What should I check out next?? Ideas on what is wrong?

I will borrow reader and check for codes today.

Any advice / suggestions appreciated!

Regards, Terry King
...In The Woods In Vermont
The one who dies with the most Parts LOSES! WHAT DO YOU NEED??

Try a system hard reset - remove the negative cable off the battery - wait 5-10 mins - hook back up, try starting it again...this sometimes solves a lot of problems.

 

[hagar]

That is a common problem, you need to replace your entire fuse block. You either call gm with your vin, it will come complete with all fuses installed, or you need to find a good one at a wrecker with all the same options. You really need to make sure they are the same ones if going used, they all plug in the same and look the same, but there are different fuse locations activated and not activated on various vehicles. Generally a loaded up Denali one will work in a lesser model unit because it has more fuse locations activated, but a lesser model won't work in a loaded truck because of locations missing the little fuse metal connectors inside.

 

[TerryKing]

OK Here's the UGLY BUT RUNS for now. THANKS to everyone who helped with this. It's an amazing Forum of Friends...
AND Thanks for the parts pointers; I have found a VIN matching fuse panel within 50 miles. THAT will be the actual solution.
BUT In The Meantime:
The UGLY connection with soldered Bronze Nails, 25A Fuse and holder:

That carefully hammered in place, just aside the broken-off fuse legs. I sprayed some contact anti-corrosion stuff first.

The Fuel Pressure came up to 55 PSI and started immediately. After warmup pressure was 45PSI.

(Don't know how to put text to right of that....)

Warmed up, ran smoothly all the time. Locked brakes and put some throttle/torque in Drive (in the barn..) All smooth running.

So I need to carefully secure that fuseholder and get the cover back on.

The Bullseye Shot by @Fless : "SWAG: Check power on both sides of fuse #21 for the Fuel System Control Module."

Just THANKS. I'll try to pay this forward. Regards, Terry

 

[Fless]

Success! Keep your eye on the MacGyver leads and make sure they're not getting too hot when you're running it.

 

[TerryKing]

@Fless, I ran this for 10 min or more and felt the top of those nails. Not hot at all as I felt it. I measured the voltage between the two tops and it was .018V (18 millivolts) and I assume that was mostly from the resistance of the fuse/holder.
I was able to ziptie the fuseholder a bit away from the edge and was able after some juggling to get the top cover completely in place (Always difficult).

Still runs OK.. that will be the situation until May.. I need to go back to Eqypt in 3 weeks; my wife has a job in an International School in Cairo. I will be working "at home" there on Educational Kits for EE students for next school year. Nice little light microcomputers and low currents!

BUT: I am wondering what's the best "Put a car to semisleep for 3 months" approach?? In the past it's been Fresh fuel and Stabil and Battery Maintainer. Worked OK several other times. MAYBE it would be better to disconnect battery and leave the maintainer on it. That way there is not 12V across so many (possibly corroding) connections? I'm afraid there are Salt Ions on the loose. Any suggestions / comments / pointers appreciated! Um, Maybe should start another thread farther up the Forum tree for that???

Regards all, Terry

 

[Fless]

If the 18mV measurement was while the truck was running, okay. But if the truck was shut off, that's more than 4A based on the minifuse (25A) conversion charts, which are estimates. The charts goes to only 10 mV.

https://m.roadkillcustoms.com/wp-content/technical-pdf/Mini%20Fuse%20Voltage%20Drop%20Chart.pdf

I have no idea about the storage issues.

 

[TerryKing]

@Fless, I ran this for 10 min or more and felt the top of those nails. Not hot at all as I felt it. I measured the voltage between the two tops and it was .018V (18 millivolts) and I assume that was mostly from the resistance of the fuse/holder.
I was able to ziptie the fuseholder a bit away from the edge and was able after some juggling to get the top cover completely in place (Always difficult).

Still runs OK.. that will be the situation until May.. I need to go back to Eqypt in 3 weeks; my wife has a job in an International School in Cairo. I will be working "at home" there on Educational Kits for EE students for next school year. Nice little light microcomputers and low currents!

BUT: I am wondering what's the best "Put a car to semisleep for 3 months" approach?? In the past it's been Fresh fuel and Stabil and Battery Maintainer. Worked OK several other times. MAYBE it would be better to disconnect battery and leave the maintainer on it. That way there is not 12V across so many (possibly corroding) connections? I'm afraid there are Salt Ions on the loose. Any suggestions / comments / pointers appreciated! Um, Maybe should start another thread farther up the Forum tree for that???

Regards all, Terry

OK, AllGood!! and here's the final WhatIDid: Got used 'good' fuse block assembly. Disconnected battery negative.
- Used "Deoxit" (https://www.amazon.com/gp/product/B00006LVEU/) on most all connections:
- On the bench: Removed, cleaned and re-inserted every small fuse and relay on the used fuse block: Coated their pins and used small handle-wipe with Deoxit to clean up the fuse/relay sockets. (Some had a little white deposit).
- Turned fuse block over and inspected all downward-facing pins large and small. Wiped every one with swab and Deoxit. None looked bad.
- Inspected the mating chassis connectors and made sure they were all physically seated correctly. Did light spray of Deoxit across all those connectors, then wiped any excess on plastic parts.

CAREFULLY positioned the fuse block in place with the arms that secure it. It's fussy to get them at the correct angle. Took couple tries to get the block to finally drop evenly in place. THEN seated the retaining arms that pulled the block down, mating with the chassis connections. Carefully rubber-hammered a little on both ends and assured the block was fully placed and plugged in.

Reconnected battery negative. Drivers seat, seat belt, key, deep breath and VROOM.. Checking.. everything Works!
Long Saga and GREAT help from this Forum...
Best Regards, Terry King ...In The Woods In Vermont

 

[Geotrash]

Thanks for following up!