Lights out on many circuits

[Zoopie]

On my '57 lost dash panel, parking and brake lights. Inspected the headlight switch and found the fuse burnt out. Replaced entire switch and still have the above results. Yet the turn signals work. Looked throughout the dash (with mini camera) and didn't find anything. Is there one point of failure or is there something more foreboding? Strange something burnt out the dash light fuse on the back of the lightswitch!

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[Digger]

I'm real poor when it comes to shooting electrical shorts. Need to have the complete wiring schematic for the 57 AND a good elec. trouble shooter. He will find the trouble. Good lick

 

[doug7740]

On my '57 lost dash panel, parking and brake lights. Inspected the headlight switch and found the fuse burnt out. Replaced entire switch and still have the above results. Yet the turn signals work. Looked throughout the dash (with mini camera) and didn't find anything. Is there one point of failure or is there something more foreboding? Strange something burnt out the dash light fuse on the back of the lightswitch!

I own a 1955 Thunderbird, but I think the wiring for the lighting system is the same as your 1957. If the lighting system is the same, the fuse on the back of the headlight switch is for the interior lights and not the dash lights. The dash lights get their power from terminal “I” of the headlight switch through the rheostat. Since you said that the headlight switch was replaced, the rheostat should be working correctly. To verify this you could temporarily connect the blue/red wire from terminal “I” of the headlight switch to terminal “R”, bypassing the rheostat.

I know that you said that the turn signals work, but before I would go any further diagnosing the parking and brake lights, I would still check the bulbs and ground connections at the lights themselves.

The stop lights get their power from terminal “A” of the headlight switch through an internal circuit breaker. After going through the stop lamp switch, there is an internal connection inside the turn signal switch before going out to the stop lamps. I would check the connections at the base of the steering column, under the dash, and the turn signal switch as a cause to your stop light issue.

The front parking lights get their power from terminal ”P” of the headlight switch and the tail lights get their power from terminal “R” of the headlight switch

I hope this information helps.

doug7740
1955 Thunderbird Blue

 

[Zoopie]

Thanks Doug, checked the one bulb in the back and replaced it just in case and checked ground (if blinker works then ground should be good I assume), checked the connections at base of steering column, still nothing. Can I take a jumper off of the battery and apply directly to the different light terminals on the headlight switch to check wire connectivity, perhaps disconnecting the wires from the HL switch before testing?

 

[Zoopie]

OK, from the headlight switch, disconnected the dash lights and jumped the hot lead from the switch to the disconnected dash wire, worked, did the same with the front parking lights, worked...bad switch! Checked with the distributor and they said they were aware of it...nice!!!

 

[doug7740]

To check the headlight switch, I would disconnect all of the wires at the switch and connect an ohm meter between terminals “B” and “A” of the headlight switch. If the internal circuit breaker inside the switch is defective, you should read an open circuit on the meter. Since terminal “A” feeds power to the stop light switch, and internally power to the tail lights and parking lights when the headlight switch is in the on position, a defective internal circuit breaker would be the cause of all of your lighting problems.

doug7740
1955 Thunderbird Blue