no power to under dash fuse panel

Hello, I was changing my battery terminal connectors a couple of days ago and ran into a problem. I noticed that when I started the truck (07 cm) that i had no dash controls, stereo, fan, power windows, mirror, etc. I figured I popped a fuse, but upon further inspection I do not have power to any of the fuses under the dash.
I checked every fuse with a multimeter and they were ok. I double checked the battery connections and they seem ok. the truck starts fine. is there a relay or fuse in the engine bay that controls that fuse panel? I don't see anything obvious.
thanks for any help.

 

RIP your main fuse.

Did you short out the battery or accidently put the terminals on backwards? Sounds like the main fuse that powers the interior fuse box has blown out.

 

No, there is no way that it was reversed, the wires wouldn't ever reach. I did do more checking and I am getting power to some of the fuses in the dash panel. If it were the main fuse, would the truck still start? Also, dome lights work. Is there a fuse behind the kick panel?

 

The "main" fuse is really a block of multiple fuses. One of which directly powers the entire interior fuse box. Yes the truck will run with the interior fuse box dead but you will have almost no functionality in the interior.

You are now saying some of the fuses in the interior fuse box do have power?

The main fuse is in the engine compartment, there is one large power wire coming from it into the back of the body control module/interior fuse box. You could check for 12v at the connector to verify power is coming into your interior fuse box.

 

This is the power coming into the interior fuse box. If this wire has 12v hot when key on/running your interior fuse box is getting power. If it does not have 12v with key on then your main fuse is blown.

If you have a voltmeter this is a quick easy check.

 

yes, some of the interior fuses have power, that was my bad.
I checked the nut at the end of the main fuse chain and it has 12V.

 

The plug I just posted coming into the body control module is the other side of the wire on the nut at the main fuse. Verify power there also.

Then try to post a list of which fuses have power vs which ones do not. If you have power coming into the interior fuse box but things are still not working, obviously you have other problems. Need to isolate which fuses are “dead” not power on either side of fuse.

 

It is all of the fuses on the inboard side the fuse panel toward the driver that do not have power.

 

I'm wondering if it has something to do the the accessory cut relay behind the kick panel. not sure how to test that though.

 

Are you sure? Did you test for power coming into the connector in the back of the interior fuse box? All of the fuses you mention are directly powered by it.

 

i'll double check.

 

Can you list out the name of some of the fuses that do not have power. I think my diagram may be flipped. Need to verify the side I am looking at is in fact the driver side.

 

The fuses in the Orange box are controlled by the ACC Cut Relay, The fuses in the Red box are powered directly from the power input from the main fuse. The green ones are power by ignition switch

Need to isolate which grouping doesn't have power.

 

no, I'm an idiot. I got it backwards. laying on my back upside down I got turned around. it is the outboard side.
I checked the lug at the fuse box again, it has power

 

on the left in this image. I think that is what you are showing in green above

 

Check this fuse 7.5 AM1

One side of it should have power. I believe it is blown out and replacing it will fix your problem.

Verify one leg has 12V, check to see if that fuse is blown out.

 

You are a legend! Back probing the fuse it showed it was good (multimeter) but 12V only showed up on one side. It must barely have had conductivity but no current could flow. I replaced the fuse and life it good. Thank you very much for your patience, help, and tenacity, I really do appreciate the help. Have yourself a great weekend.

 

It is kind of confusing but that fuse takes the 12v signal coming into the interior fuse box and feeds it into the front side of the ignition switch. When you turn the key on the ignition switch passes the power on to all the relays and then fuses that were not working.

With that fuse bad you had no power going into your ignition switch which means none of the relays were operating when you turned the key on.

Glad you got it fixed.

 

Hi Jeff, I have a similar problem in GMC Sierra and hoping you can help
I did the same apwisher where I disconnected then connected my battery, then half of my accessory electronics stopped working. I checked the fuses under the hood and the dash, all are working BUT the fuses responsible of the non-working parts are NOT getting power V12 while other fuses of working items are fine

- Working items:
1- Radio
2- Aux
3- x1 power outlet
4- passenger window front and rear
5- dash backlights (only during daytime)

-Non-working items:
1- driver side windows front and rear
2- x2 cigarettes power outlets
3- left turn signal (the blinking inside but the lights outside are not corresponding, I checked light bulbs and they are working)
4- lock/unlock switch (I heard a click in the Harness Connector when I click it but no action happening). The remote is working with the car, it turns the lights and horn on BUT it doesn't open the locks)

I have the following errors when I plugged in OBD2:
- P0606
- B2615

I changed and re-flashed the BCM, now the "engine" sign is gone but the problem remain the same!

Would appreciate any help please

 

What year make model engine size ect. I dont have access to an GM stuff but I think I know of a source online. I need more info on the vehicle, type ect.

 

its GMC Sierrra 1500, the year 2008 SL. Engine 4.8L Gas. I checked more fuses under the hood and it seems some also are not getting any power (ones related to the non-working items). I just checked the mega 175amp fuse coming from the battery and replaced it. Nothing changed and the problem is still there!

I also checked all the fuses in the underhood fusebox, some area not working (especially the one related to the truck accessories)

 

Can you list out the labels of the fuses that are not getting power, that control the non working accessories?

Form looking quickly some other big fuses in the engine fuse box could be the problem.

60A LBEC1
60A LBEC2

These two fuses seem to branch off and power other smaller banks of fuses. Could me more but if would help to know exactly which of your fuses do not have power.

 

Thanks for the reply Jeff! Here is a list of the fuses which are not working (please note that I turned the engine on and tested them all BUT some might not have power since that specific accessory is not incldued in my truck model)

The 60A and 40A I checked visually and they looked fine, I didn't check them with multimeter since I assume they look fine. I can test the above 60A fuses and replace them if you believe they are the problem!

 

I don't think the Fuse #s line up between your graphics. Based on everything you are describing I really think its a bad fuse somewhere. The GM diagrams are not exactly easy to read but I will look at them closely.

I would set your multimeter to the continuity check (beeper) and check every fuse in the fuse box. They should all beep and have continuity.

 

I did check all fuses under the good and dash with the beeper, all beeped and not damaged (I only checked the small fuses, not the 40A or 60A, these ones I checked visually). It's only when I check with lighter that I notice some fuses are working while the rest are not.

I did a test on the dash fuse block and focused on Left and Right turns fuses. The right turn fuse has power going through it while the left does NOT have power, it correspond with the state where my left turn signal is not working.

I checked the wires coming into the under hood fuse block, all are running fine. I'm not sure if the fuses that are not working in the under hood block because they are not active or in use OR its because there is something blocking the electricity from going there (like faulty PCM or software).

Any help is greatly appreciated, I have been stuck with this problem for a month now and driving the truck without left signal is dangerous

Im checking the 60A fuses you mentioned above today and will update you shortly

 

Which fuses specifically are you referencing here? " Left and Right turns fuses"

I just figured out the secondary table is for the interior fuse box in the dash. The top graphic is the engine fuse box. correct?

 

The more I look at this I am pretty sure your LBEC 2 60A fuse is bad. It powers over half the interior fuse box including the power outlets and most fuses you marked off in red on the interior box.


For the power outlets.
Battery ----- LBEC 2 Fuse ------ AUX PWR Fuses.
This fuse is the only thing in the way between the AUX fuses and the battery. The only way they wouldn't have voltage is a break in the line.

I am seeing Driver side lock fuses, driver side blinker fuses all trace back to this LBEC 2 60A


The right turn and stop fuse is on LBEC 1 and is working. The left turn and stop fuse is on LBEC 2 and is not working. More evidence I think this is all tied to a bad LBEC 2 Fuse.

I would check all of these "bigger" square type fuses, especially LBEC2 (I think they have a viewing window in the top) This diagram you posted shows its to be #74 fuse, the wiring diagram I am looking at shows it to be the #72 fuse. That is why I say check them all.

 

OMG!! you were 100% right, its the LEBC2 and the location is 72 (I had the wrong diagram online, I checked my diagram in the car fuse block cover). For the life of me, I have no idea how the fuse was removed but someone removed it from its location. I found the location empty and it looks it was removed recently since the place is clean and not dusty like the other slots. I put a 60A fuse and now everything works like a charm.

You are a lifesaver, thanks a lot <3

 

That will be $100 Bob, joking but no telling what a dealer would have charged. Have to love the internet, a few messages and 20 mins of studying a diagram and it’s fixed.

congrats, now you can go enjoy your truck again even if it’s not a Toyota.

 

You really got to love the internet! I have been looking and trying for over a month. I already paid over 700$ for BCM and reflashing which was not the problem obviously! When I texted I had a good feeling that you will be able to figure this even though it was not a toyota lol

thanks again, next truck will be a Toyota for sure