1970 c20 more electrical questions

[70chevlow]

Ok so i have traced my electrical draw problem as far as that when i unplug the dash that it goes away so does this mean it coukd be either the gauges or printed circuitboard is what is drawing tge power or when the gauge cluster is plugged in does it backfeed somewhere.

[airdale94]

It sounds like that it what it's doing, back feeding. Hence your problem. You could have a short to ground in your printed circuit. Try pulling your instrument cluster fuse, it's a small 15a to confirm. Do you have anything staying on, on a key off situation,ie: gauges, a light?

[70chevlow]

I believe fuel gauge stayed on at least a couple times.

[70chevlow]

Ok so i got another dash on ebay and same issue when no dash is connected there is no power draw whe. I i plug the dash in its draws .16 amps so what do i check now? Sorry i just am not good with electrical.

[VetteVet]

Are you able to check each pin on the cluster plug with a multimeter and look for 12 volts, especially on the pink fuel gauge wire and on the gray instruments light wires.

Do you have a gauge dash or a idiot lights dash?

[70chevlow]

It's a gauge dash and I'll check tonight and see if they all have 12v

[70chevlow]

so are the plugs supposed to have 12volts or no? some do some dont

[VetteVet]

Originally Posted by 70chevlow

so are the plugs supposed to have 12volts or no? some do some dont

What I'm trying to find out is if you have power on any of the wires with the key off. The pink wire is the power wire for the fuel gauge and the temperature gauge. The gray wires are for the instrument lights and they only have power when the light switch is on.

The two small wires on 1 and 12 are for the ammeter and they will show power all the time unless their fuses are blown. Did your ammeter work?

That's about it for power wires.

There's a cluster feed fuse in the fuse panel that you can pull and it should kill the power to the cluster. If it has power with the key off you may have a short to a power wire in the fuse panel. Try pulling that fuse with the cluster plug installed and see if the drain goes away. Be sure the key is off.

[70chevlow]

ok so sounds like I must have a short to a power wire than. The pink wire was hot and so are 3 or 4 others ill check exactly what ones tomorrow. So now would I be check the wires behind the fuse panel in the engine compartment or do i have to remove fuse block to access them?

[VetteVet]

Originally Posted by 70chevlow

ok so sounds like I must have a short to a power wire than. The pink wire was hot and so are 3 or 4 others ill check exactly what ones tomorrow. So now would I be check the wires behind the fuse panel in the engine compartment or do i have to remove fuse block to access them?

Well let's skip back up to the power source for the pink wire, the key switch.
In this diagram it shows the red power wire to the key switch which powers the pink wire when the key is on. Normally the pink wire is dead until the key is on but it may be that your switch is shorted and the red wire is connecting with the pink wire at all times.




Looking at the top of the diagram, you see the wires going to the key.
Red, pink, purple, brown, brown/white stripe.

In the second diagram, the pink wire continues down the center of the diagram where it joins another pink wire which is the ignition coil wire, then it continues on to the fuse panel to the cluster pnl fuse.
if the pink wire is hot with the key off then it figures that the ignition coil would also be hot with the key off, If you have converted to HEI ignition and are not feeding the coil from this pink wire then only the cluster would be getting power. Otherwise pulling the cluster plug would still leave the coil hot.



Ignore any arrows,,,, they are for other posts.

There are two screws on the fuse panel diagonally opposite each other that if you take out should let you see the wiring behind the panel. I'll see if I have a picture.