I need to find a fuse

asilverblazer · November 4, 2004

I have been replacing the bulbs in my instrument panel as they burn out, the last one was in the 4wd switch. I wasn't sure what bulb to replace it with so I took the wire leads to the new bulb and placed them on the terminals of the board, it worked but I shorted it out removing it, My big question, I blew the circuit that lights all the instrument panel LIGHT BULBS, not LED's. For example with the parking lights on the only in dash lights are the PRND321, Odometer and LED's on the 4wd switch and HVAC control, dome and courtesy lights work, the rest are dead. I checked every fuse in the panel on the side of the dash and in the electrical center under the hood, none are blown. So unless I have bone headed this one and missed finding the blown fuse, I can't find the problem. Can anybody help guide me to the exact fuse, fusible link, circuit breaker to check, other than the ones that say "Instrument Cluster", or "Light" in some form?

Many thanks for the help.

sperry · November 4, 2004

There's an "Illum" fuse on the left bussed electrical center... 10A

(The lower left side of the IP/Dash)

asilverblazer · November 4, 2004

There's an "Illum" fuse on the left bussed electrical center... 10A

(The lower left side of the IP/Dash)

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Are you sure this is it, because I have checked at least twice, and it looks good, are there any others. I'll replace it tonite and see if it fixes it.

Thanks

sperry · November 4, 2004

That's via a schematic...

Most anything in the path could have fried. Is it the cluster only?

asilverblazer · November 4, 2004

That's via a schematic...

Most anything in the path could have fried. Is it the cluster only?

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Its the whole dash. Maybe the fuse is messed up not "blown" like I would expect.

sperry · November 4, 2004

IGN 1 and IGN 0 fuses OK? So it effected the guages too?

or just the filament lights..

asilverblazer · November 4, 2004

IGN 1 and IGN 0 fuses OK? So it effected the guages too?
or just the filament lights..

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Just filament lights.

I checked both of those too.

sperry · November 4, 2004

I can't post the sch here or the way the e-mail is addressed. E-mail me with the e-mail addr you're at so I can attach the print.

(I'm going to lunch in 5 min!) or wait for apx ½ hr.

asilverblazer · November 4, 2004

I can't post the sch here or the way the e-mail is addressed. E-mail me with the e-mail addr you're at so I can attach the print.

(I'm going to lunch in 5 min!) or wait for apx ½ hr.

<{POST_SNAPBACK}>

You've got a PM.

Thanks

asilverblazer · November 5, 2004

I can't post the sch here or the way the e-mail is addressed. E-mail me with the e-mail addr you're at so I can attach the print.

(I'm going to lunch in 5 min!) or wait for apx ½ hr.

<{POST_SNAPBACK}>

You've got a PM.

Thanks

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Well I looked at every fuse connected to these lights, no luck. I called a dealer to see if they had any suggestions, they told me either the BCM or head light switch, I looked at the schematics and I think they are right. One of those two things must have got fried. Does this sound possible, or reasonable? By the way does any one have part numbers for the headlight switch, and BCM? Is the dealer the only one capable of programming the BCM?

Thanks for the help, and a special thanks to Sperry for the help.

sperry · November 5, 2004

Borrow a compatable cluster and try it. They have been known to go dead. You could isolate it better that way. Speedo shops may be able to fix it, since (if it did toast) they would have to xfer odo, etc, and charge you to attempt the recovery too.

If it's the BCM and it's stock, the replacement has to be programmed. The dealer hooks it up to a download for your truck and flashes the info back into the new one.

Bummer...

asilverblazer · November 6, 2004

Just an update...

I don't think it is the instrument cluster because all the lights don't work.

I unplugged the head light switch thinking that that might eliminate one possibility.

This leaves only the BCM to blame, if that is the case, if I disconnect the gray wire from the BCM thus eliminating its control of the lights, could I control the dash light via the switch. My thinking is that the BCM is turning the "daytime" dash lights off (bright Radio display) and not switching the "night time" lights on. So If the BCM is bad preventing the lights from coming on, unplugging the wire would allow the switch to turn them on. It makes sense to me but typing it probly don't.

Thanks.

sperry · November 6, 2004

You isolated that... I somehow, had a mind-set that it was the cluster only.

OK, no voltage from the BCM, everything else is there... But this went out from an OOPS. so I doubt that the Light sensor would be to blame.. But worth a check.

I'll keep checking here... Are your documents adequate?

TROYROBO · November 7, 2004

it's the headlight switch--blew mine about 18 months ago in my 2000 gmc--got a new switch from dealer --fixed problem--also bought a backup switch off e-bay in case it happens again

asilverblazer · November 9, 2004

Well I narrowed it down to the BCM because the headlight switch controlled the head lights and parking lights properly. I figured the ownly variable is in the BCM and with unhooking the headlight controller there was no change in the problem. I knew it wasn't it just the cluster because all dash lights were not working, the radio, HVAC, etc.

So since my last post I pulled the BCM out and looked at it real good trying to find a visible burn (long shot I know). No luck at this point I decided I need to buy a BCM, if that doesn't work a head light switch and if that doesn't work a new truck.

After rolling it around in my ticker I remembered that the power door lock switch and window switch lights were on the same circuit as well, so I go back out to see if they work. Dadgum, they do! But they aren't controlled by the dimmer. So I messed with the dimmer some more, earlier I just rolled it to dim and back up to bright with no luck, but I messed with it enough this time to get the lights to flicker on. To sum it up the dimmer works at absolute highest possible setting, I must be careful not to hit it or either the dome light comes on or the lights go out.

All in all I am glad thats all it is, thanks for the help guys and Troyrobo wish I coulda read your post sooner.

Thanks again.