dash lights issue

[str12-340]

So this is about a 1970 Dart with new stock wiring (M&H). It has a standard dash cluster (not rallye). It has a cluster of Sun gauges (5 in all), also all new and also newly wired by me. I wanted the gauges to dim with the dash so I wired the new gauge lights to the instrument fuse ON THE HOT SIDE, with its own fuse.

I have had the dash lights go out a couple of times and it and each time the bitty 3 amp fuse in the fuse box was blown. The gauge lights never go out. Put in a fresh fuse - turn on the parking lights, dash lights come on and dim properly. Today I figured out the if the dash lights are on WHEN I START THE CAR it blows the fuse almost immediately when the engine catches. Replace the fuse and have the lights off when when starting, and then turn on the dash lights while the car is running and they work fine. I tried a bump up to a 5 amp fuse, but those blew during start up too.

Anyone have suggestions as to where to start?

 

[CRUZE 418]

Just tried peeking in behind my fuse box on my '69, looks like I piggybacked to a spade on the back side of the instrument fuse.

 

[Oldmanmopar]

I tied into the ash tray light wire. Ran all wires and hook ups through the lighter hole and notched and old ashtray. Gauges held in up by the dash screws and stopped from dropping by the tach resting on the pad.

Everything can be unplugged and removed without evidence of them being there. Used a piece of a dash cap to protect the pad

 

[67Dart273]

So this is about a 1970 Dart with new stock wiring (M&H). It has a standard dash cluster (not rallye). It has a cluster of Sun gauges (5 in all), also all new and also newly wired by me. I wanted the gauges to dim with the dash so I wired the new gauge lights to the instrument fuse ON THE HOT SIDE, with its own fuse.

I have had the dash lights go out a couple of times and it and each time the bitty 3 amp fuse in the fuse box was blown. The gauge lights never go out. Put in a fresh fuse - turn on the parking lights, dash lights come on and dim properly. Today I figured out the if the dash lights are on WHEN I START THE CAR it blows the fuse almost immediately when the engine catches. Replace the fuse and have the lights off when when starting, and then turn on the dash lights while the car is running and they work fine. I tried a bump up to a 5 amp fuse, but those blew during start up too.

Anyone have suggestions as to where to start?

You say on the "hot" side. You mean you have it hooked to the tan wire or is it hooked on the orange wire(s) side?


Is it possible a grounding issue with the sun package?

Last, have you tried disconnecting the Sun group, and the problem goes away?

A puzzle, for sure

 

[str12-340]

The aftermarket gauge light wiring is attached to the side of the fuse that is hot without the fuse in place - I believe that it is fed by a wire that goes from the headlight switch to the INST location in the fuse box. There is an inline fuse for the aftermarket gauge wiring so that the power for the aftermarket gauge lights does no go through the factory fuse at all (to avoid overloading it). The other side of the fuse is attached to 5 or 6 factory orange wires (two connectors) that feed all the original dash lights - cluster, radio, heater controls, shifter position light etc.

 

[str12-340]

The question is a good one so I disconnected the aftermarket gauge lights from the system. The dash lights work fine without the engine running. I shut them off, started the car and they work fine with the engine running. Shut the car off, left the lights on and started the motor and the fuse blew, so I don't think it is in the aftermarket gauge lights.

 

[67Dart273]

Do you have a feel that anyone kinda hacked up the wiring? I can think of no crossover point that would connect the start or run circuit with the instrument lamps.

In case you are unaware, here is how they work. The headlights switch has two power sources. One, only for the headlamps, comes from the big welded splice in the ammeter black wire behind the cluster.

The park/ tail/ dash lamp power comes from a fuse in the panel. When the light switch is in park or head, power goes from the switch, through the dimmer control, and out of the tan wire, down to the fuse panel INST fuse. That then goes out on orange wires to all of the dimmer controlled dash lighting.

I am stumped

 

[CRUZE 418]

I'm confused as to where you have power connected. I have 2 sets of 3 gauges in 2 cars hooked to the male spade that would be directly behind the instrument fuse in you fuse box. It's a piggyback orginal connector behind the instrument fuse. I have never had a problem. My tach light is also in this line, so 4 lights. No inline fuse either, that's the instrument fuses job.

 

[str12-340]

I'm confused as to where you have power connected. I have 2 sets of 3 gauges in 2 cars hooked to the male spade that would be directly behind the instrument fuse in you fuse box.

I'm glad that you have had no problems, but the fuses are sized for the load that they are expected to handle. If you add things to the spade that you are using, you are adding to the load on the fuse because you are adding them after the fuse (power for the addition goes through the fuse). To avoid this you can add things to the opposite side of the fuse (in effect before the fuse) and protect the added wiring with a fuse in that added wire.

 

[CRUZE 418]

Well, that may be so, but I don't have a problem, haven't had a problem, nor have I upped the fuse size.
I'm out.