Hi all,

So i recently bought a new tach and water temp gauge, both by auto meter. The only difference between these gauges and my old ones is that my water temp gauge has a built in light and not the bulb type light it had before. Well after wiring these up together and connecting them to my light switch they fried the circular spring that is used for dimming. The spring got to hot and broke basically. So i got a new headlight switch. What im wondering is why is it destroying the switch like this. Everything is grounded right. Am i missing something here? The only solution ive thought of as of now is wiring the lights for the tach and water temp gauge to a switch separate from the normal light switch. Any ideas Thanks

 

Is it possible thet these new gagues are pulling more of a load through your headlight switch? When I upgraded my 65 to halogen headlights, I also upgraded my headlight switch from the standard 65 to a 69, which is designed to handle a heaver load (because of the dual headlights on a 69). I got the idea from a member of my local Mustang club, who has done this before. I had to use part of the mounting assembly from your old switch, which the 69 switch doesn't have, but the connectors are exactly the same, so no splicing or modification to the wiring is necessary. Everything works fine with my new switch so far. If you think that this might solve your issue, PM me and I can provide you with additional information on the upgrade.

 

I went with halogen lights and installed relays to handle the load on the switch. I also made a new wiring harness because the original wiring was causing the driver side headlight to be dimmer. This made a big difference in the lights brightness.
Pictures and info:
http://chris66dad.tripod.com/id15.html
You can buy a premade harness and relays here for $30:
http://www.lmctruck.com/features/fbr/FBREL1.htm
It is for a Ford Bronco but the connectors are the same for Mustangs with a single High/Low bulb.

 

I think the problem might be the increased load from the gauges. They both are connected to the blue/red wire which connects to the headlight switch assembly. At first i had both of them connected together and then to the blue/red wire but i found my new radio doesnt need a light wire going to it so i connected one of the gauges to it which is basically the same thing since the radio wire is blue/red. I would hate to have to wire these gauge lights to a fuse box separately but i cant keep buying headlight switches. The 69 switch is a good idea but i dont know if it will make a difference since its the gauge light load that is kill the switch and not the headlights.

 

Using the headlight relays will just about eliminate all of the load on the switch. The switch will only see the pull in current of the relay which is very small.
The harness I listed is plug and play with no modification to the original wiring

 

what if i install a relay between the gauge lights and the headlight switch? would that decrease the load the switch experiences.

 

It would be overkill for the gauges but would probably work. The load the headlights pull is 100X that of what the gauges pull so you would just be pulling the load on the HL switch down below max. The better idea as mentioned would be to put the relay on the headlights and decrease the majority of the load. Putting the relay on the gauges decreases 10% of the load, putting it on the headlights decreases 90% of the load on the switch.
http://www.danielsternlighting.com/t...ys/relays.html

Jon

 

I was under the impression that the gauge light wire that connects to the headlight switch is separate from the headlights themselves. The whole switch isnt breaking. Just the spring used to adjust the brightness of the dash lights. Its getting to hot and melting but i thought that wouldnt involve the headlights.

 

The headlight switch is all one piece, it is the relay/fuse for all the lighting, the dimmer coil is part of this switch so power goes through it just as it does for the headlights, TS, etc.
Jon

 

I also suggest headlight relays. I have the RJM relay harness.