Gauge cluster not working at all

[garftree]

hello, just a quick overview of the truck:
so i just picked up a 1986 c20 suburban with a 454 and rebuilt 400 trans. i was planning on pulling the motor and trans(this is why i got it) out putting it in my 79 c10 but im not sure yet.

so it has very little rust, its actually not bad at all, so the only problems that i knew of. it was missing the back window, the gearbox leaked and so does the power steering pump. both he gave me extra.

now that i have had it and went to drive it at night the dash lights never came on, and i also noticed all the gauges except the speedo were not doing anything. so i pulled the cluster and checked it over, great shape all around. so i thought it was bad, so i pulled one out i had from an 86 dump truck, it didn't do a thing, the one out of my c10 (which is working fine) does not work either.

i don't have my multi meter until tomorrow night, or i would test the plug.
i have checked the fuse for the dash its fine.
anyone have any ideas why its completely dead?

 

[Georgeb]

No ground?

 

[Jarhead79]

The 86 dump truck I don't think would work anyways, they're pinned different than the older trucks I do believe

 

[garftree]

the ground from the wire harness goes directly to the metal dash(appears to be factory ground it appears.i really need to get my meter back.

i was guessing the dump truck gauges wouldn't work, just a random swing in the dark, but i would think the 79 c10 cluster would work that truck runs and those gauges worked.


my thought it is the printed circuit, but still the other gauge cluster should have worked. at least something move or light up.

 

[chengny]

Two fuses involved in this.

One - in the slot labeled GAUGE/IDLE - supplies power to drive the actual gauges. The other - a 5 amp in the INST LPS slot - supplies the various instrument lamps. But it doesn't get its power from the fuse block. That power is lead out from the rheostat in the H/L switch.

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[garftree]

I got my multimeter back yay!.
Ill check that other fuse you speak of when I get home tonight.

 

[chengny]

Also - for the lighting issue - verify power (3-9 VDC depending on rheostat position) is available at the dark green wire coming out of the H/L switch.

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As for gauge function, that pink/black circuit goes a lot of places besides the dash panel. The power for the detent solenoid in your TH400 transmission for example:

i just picked up a 1986 c20 suburban with a 454 and rebuilt 400 trans. - is on that circuit. Does the transmission kickdown?

BTW - most of the engine controls on an LE8/LT9 (i.e 454) motor are powered by that circuit as well.

If that fuse is open and you replace it, you might realize a big improvement in performance - if it is the LT9 (TBI) version. If it's carbureted, maybe not such a change. But your transmission should start kicking down.

 

[garftree]

so i got my multimeter and tested everything i could think of, nothing. it wasn't until my 3rd time testing around that i noticed the harness going to the fuse box was crushed looking.
i pulled it apart and it looks like someone hit it with an axe. i rewired them all, and i got gauges. not lights tho. so checked the fuses again both were blown. replaced them and all is well. drove it 2 days now and everything works.
that blast seat belt chime is loud as hell. but it works.