Urgent dash light help!!

[black73cuda]

I guys, i am kind of pressed for time to figure out a issue with my car.. working on a 73 cuda

i am haveing problems with the dash lights... I have done the dash dimmer switch bypass and that works great nice and bright when working.

The problem is is when i go to start the car the fuse number 5 blows... I can pull the blown fuse with the car running and install a new one and all is good until i turn the car off and hit the starter then it blows again?

I was hopeing to get some insight as to what could be causeing this?

My owners manual shows the #5 fuse is a 5amp fuse and it controlls : Cluster lamps, radio lamp, A/C or heater control lamp, Gear select lamp, Ash tray lamp.

Any help would be greatly appreciated   

mike-

[ShelbyDogg]

Solder wires to each end of the blown fuse and solder a tail light bulb to the 2 wires.  When it tries to blow, it will light up bright.  When it does, start unplugging all of the wires going into the ORANGE WIRE plugs.  This circuit originates at your headlight switch, which goes to the dimmer, then that upper-right fuse then to the orange wires.  Those include the glove box light, ashtray light, gauge lights and sometimes the heater switch panel light depending on if you have the delay timer and map light circuit.


Do the light in the fuse deal. It will keep you from blowing 20 fuses trying to find this short ar high draw.
Did it not blow till you did the dimmer bypass?

[black73cuda]

Solder wires to each end of the blown fuse and solder a tail light bulb to the 2 wires.  When it tries to blow, it will light up bright.  When it does, start unplugging all of the wires going into the ORANGE WIRE plugs.  This circuit originates at your headlight switch, which goes to the dimmer, then that upper-right fuse then to the orange wires.  Those include the glove box light, ashtray light, gauge lights and sometimes the heater switch panel light depending on if you have the delay timer and map light circuit.


Do the light in the fuse deal. It will keep you from blowing 20 fuses trying to find this short ar high draw.
Did it not blow till you did the dimmer bypass?

The dimmer switch never worked so i dont know for sure. I left the switch umpluged and used just a jumper wire.



I will try that trick tomorrow, thought it was kind of odd that it only will blow when you start cranking on the car.

[ShelbyDogg]

When you jumped your dimmer connector, you just hooked the middle one to the side one and not the yellow wire right? The yellow one is to turn on the dome light. The other 2 are to dim the dash lights.

[dodj]

Are the dash lights on all the time?  If they are, That would likely be the problem. Normally everything is turned off while cranking. If you're not sure how the dimmer was bypassed, I'm assuming someone else did the job for you? Sounds like a high probability area to be looking. Dimmer maybe jumpered to battery 12v, on the wrong side causing a loop that shouldn't be there? (back through thedimmer to the fuses)

[black73cuda]

Hello, yes i have the plug disconected from the dimmer switch then i ran a jumper wire between the black and the tan wire... i left the yellow one alone.

[black73cuda]

Are the dash lights on all the time?  If they are, That would likely be the problem. Normally everything is turned off while cranking. If you're not sure how the dimmer was bypassed, I'm assuming someone else did the job for you? Sounds like a high probability area to be looking. Dimmer maybe jumpered to battery 12v, on the wrong side causing a loop that shouldn't be there? (back through thedimmer to the fuses)

No the dash light are not on all the time...

i bypassed the dimmer switch myself (jumped the brown and black wire and just left the plug unhooked from the dimmer switch... the yellow one is not being used....

Am i suppose to leave the dimmer switch pluged in and jump the two wires or can i just leave it unpluged from the dimmer switch period?

I have unplugged every thing that runs off that fuse that i could see and it still does the same thing.... fuse will blow as soon as i turn the starter over for a second or 2.

[black73cuda]

Note.... the fuse only blow if i start the car with the headlights on....

in other words, if the head lights are in the off position then i start the car it's ok... i can turn the head lights off and on with no problem.

something must be shorting it the ignition switch?

[dodj]

If it was shorting in the ign sw it would happen all the time. As for the wires you connected at the dimmer, I don't remember the wire colors and I'm away from home so I can't say if if you jumped the right ones or not. But the issue seems to be tied to the hlight cct and fuse5.

[ShelbyDogg]

The orange wires only go to 4 places (if you don't have the light package. 
1. 3 pin connector that goes to gauge lights, ash tray, and glove box.
2. Radio light
3. heater switch panel light.
4. wire for the shift indicator, going up with the ignition switch wires, usually 3rd pin up from the bottom
You unplugged everything, right?

All I would do is remove the jumper from the 2 pins at the dimmer. Put in a 5 amp diode in place of the jumper between the BLK-Yel and tan wires. I would have the stripe facing the center (tan) pin. See if the fuse still blows.  Don't worry about the yellow wire. You can run that to a switched ground to turn on your dome light later.

If you only have 1 amp diodes, hook them up side by side. If you hook it up backwards, the dash lights won't come on, so reverse it.

Tell me what happens.........

[ShelbyDogg]

I have a car wired the same way and it just started blowing the same fuse. I have a wire soldered between the middle pins and the outside pin, but the plug is still plugged in.   Lost all dash lights but the parking lights still work due to being on a different circuit on the headlight switch. I should have my car at my house a week before the Nats so I'll troubleshoot it and see what is happening.  Did you get yours working?  Do you have the dimmer switch plugged in or just wired together at the plug?

I put another working dimmer switch in place of my bypassed one to see if the fuse still blows. If it does, there must be a wire shorting to ground some where.

[mrwfp]

I also had a 73 'Cuda that did the same thing.  Turns out that the cigarette lighter was also on that same circuit/fuse.  It went bad, causing a short that blew the fuse anytime the lighter made contact.  That took out the dash lights and tail lights on my car.