87 guages not working...

[martindc1]

Ok I'm new to the 73-87 trucks. My K(V)-10 gauges are not working and I'm having trouble finding information in searches. The speedometer and illumination work, but the temp, oil pressure, fuel gauge and ammeter don't work. It seems like when I turn the lights on the temperature gauge goes to 270. Any ideas on where to start looking? The truck does have a snow plow on it and imo the wiring is a little cobbled but not too bad I guess.

[jhngardner367]

try tapping hard on the face of the dash,with the key ON,and see if it makes them work.
If it does,they have a loose contact,where their studs go through the metal contact clips(see my post: 'gauges/'85lwb).
If they still don't work,reach up under the dash,and wiggle the push-in connector,at the back of the cluster,and push it in firmly.They sometimes come loose.
If neither of these work,you may have a bad printed circuit,and the cluster will have to come out,to replace it.

[bilfman]

First thing to check is if the sending units are hooked up. Temp will be on the drivers side, typically a green wire on the side of the block. Oil usually drivers side either by oil filter or distrubutor. My last truck had no sending units. Found some at a wrecker and all was fine.

[oldschool18]

did you just buy the truck or is this something that just started, my uncle has a 79 and someone put newer dash in it and i had to rewire it wasnt to bad to do. if you got the time pull the bezel and take some pics and some pics of your main wire harness and i'm sure you can get some advice

[martindc1]

Just got the truck within the last week. I'm pretty happy with it, but it has a few kinks to iron out - this being one of them. Not bad for a 25 year old truck though.

So the gauges are on the same circuit as the taillights? Since the taillights etc work correctly it could be a ground or faulty PCB?

[martindc1]

Oh and another bit of information is that when the dims are on the brights indicator light is on. Also the horn doesn't work.

[martindc1]

Ok the newest update is that the fuse was blown. All the gauges work when I replace the fuse but the fuse only lasts about 30 seconds. The buzzer doesnt sound all that great. The fuel tank was just replaced too, so I'm wondering if there is something wrong with the sending unit.

[hartbraker]

if the fuse only works for about 30 seconds, that means your wires are shorting out somewhere. Either there is a bare wire that needs covered somewhere or two wires are touching each other somewhere in the circuit. Can be a pretty annoying problem to fix as it takes time to sort through all those wires. Check places where wires could possibly rub or where many wires are grouped together to start and work from there.

The sending units often need adjusted if they're inaccurate... i.e. if you know the tank is full and it's not reading full... just something to consider.

[martindc1]

One funny thing that happens is that if the lights are on, the temperature gauge maxes out - this is with a blown fuse. So I'm wondering if the wire from the sending unit could be the problem?

[martindc1]

If I unplug the fuel sending unit the fuse still pops. So I guess the problem could be in fuel gauge wire leading to the sending unit. I have another idea that it could be an abandoned wire somewhere from the oil pressure gauge - see my other post. I'm about to pull my hair out.

[martindc1]

With the cluster plug unplugged the fuse still blows almost instantly. So I'm guessing the short is in the wire coming out of the fuse block. Looking at the schematic im trying to figure out if anything else is powered off this circuit. Im going to have a closer look at the fuse block to see if the cobbled up snow plow wiring has anything to do with it.
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[bilfman]

Electrical gremlins can be a real pain. You need a general understanding of autoelectrical to chase this stuff down. Sounds like you have a decent grasp of it. It is mostly time and eliminating variables form this point in. Work through 1 thing at a time, trace all wire in the circuit and carry on to the next. Eventually you will find the issue. I had many gremlins on board when I got my dually. Oil pressure, temp, tach, heater fan, wipers, dome light, cargo light, cab lights and dash lights.

I took all these on 1 at a time and got each working. It is very hard to fix an electrical problem via forums as they can be so many different things. Though a blown fuse is a short somwhere in the circuit.

[hatzie]

I agree once you know which circuits its just work to chase em.

Fuse 1 feeds the cluster IGN power wires, 4WD light, & Seat Belt Buzzer

If you have em these are off fuse 1 too... Cruise Control and Aux Battery Relay