Checking a light dimmer switch

[Flchallenger]

71 challenger and was dissambled new wiring harness installed and blowing the dash light fuse. Pulled the switch out and it doesn't have a smooth transitiion on the ohm meter when I turn the dial. Cleaned it with electrical cleaner. I have a multi meter with several ohm settings 200 to 2m. What setting would I use? any advice on how to check this switch. Lights did work but fuse blue.

 

[Flchallenger]

Ok so I put a multi meter on it at one end of the range I get 3.4 ohms set on 200 ohms. I rotate and it jumps to a 1 in the center area and back to 3.4 or 3.6 at the other end of turning it. Is it bad? Dead in the center? I don't see how it can read resistance in one are but not another. Maybe the contact is not pressing constantly against the contact? Any advice/ideas ?

 

[Challenger RTA]

Being in one position for a long time erodes or melts the wire.HEAT.

 

[Flchallenger]

I need to replace it then. Thanks

 

[devinism]

I need to replace it then. Thanks

That still won't cause the fuse to blow, unless you can see the rheostat (spring) loose and hitting the metal body of the switch. An open circuit, which is common on ebody dimmers (I've rebuilt hundreds of them), will just cause no dash lights.
The orange wires are dash lights, radio light, and possibly others. Look for one going to ground. Wrong bulb, broken bulb in the socket, etc.
I've even seen the plug for the dimmer (3 wire) wired incorrectly. One of the wires is a ground for your dome light system. Connected to the wrong terminal and ........power to ground.

 

[73-Cudah2]

I have a quick question if one bulb is out will they all go out then
in the dash?

 

[73-Cudah2]

Also have you opened a headlight switch for 73 Cuda?
If so how did you open it by bending the crimped edge
up?

 

[devinism]

I have a quick question if one bulb is out will they all go out then
in the dash?

No

 

[devinism]

Also have you opened a headlight switch for 73 Cuda?
If so how did you open it by bending the crimped edge
up?

I have rebuilt 100+. I have a very small cutoff wheel on my dremel that use to put a small cut in the middle of the crimped section. It makes it easier.

 

[73-Cudah2]

Is there an inter fuse that can blow? I read a post and someone said that if so you have just replaced it or
what are common things you find wrong and have you posted and pic of the internals of the switch?
thanks!!

 

[devinism]

There is a circuit breaker internally, but it only affects headlights.

What isn't working?

 

[73-Cudah2]

Dash lights but now the running lights are out, 5 amp fuse has no power from headlight switch and no power going to dimmer. I think the dimmer is bad also. I just trying to get the 5 amp power then check dimmer also.
I test with key on position and checked all the fuses only the 5 amp doesn't have power going to it and
that powers the dash lights.

 

[73-Cudah2]

Here is a diagram to bypass dimmer switch not sure if correct tho?

 

[73-Cudah2]

Until the dimmer is repaired.

 

[devinism]

Power goes through the fuse, then into the headlight switch (terminal B2 (pink?)). Then out of the headlight switch (terminal R) and splits. 1 wire to the dimmer switch, 1 to tail / running lamps.

No power on either side of the fuse? Clen off the terminals on both ends of the fuse, and the terminals that the fuse snaps into.

 

[devinism]

Here is a diagram to bypass dimmer switch not sure if correct tho?

Yes. Just make sure you jump tan to the yellow with tracer wire. The solid yellow is the ground wire for the dome light function.

 

[73-Cudah2]

Okay I took mine apart, not seeing anything that could be bad in the switch?

 

[73-Cudah2]

So it's All mechanical internal so not sure what are you looking for when it goes bad?

 

[73-Cudah2]

I didn't crimp it back to gether until I test it.

 

[73-Cudah2]

Tested and it still only works for headlights? Thanks for your help. any tips as to why running lights fail to turn on?
key is in on position when tested.