Electrical Problem with 72' Barracuda (lighting)

[rcuda22]

I'm am having trouble with getting all my lights to work. Ive done a complete restoration of the car and I'm now in the final stages of finishing things up. I have fixed all the wiring harness exactly to match the diagram. The problem I'm having is that the tail lights brake lights fog lights and sidemarkers do not work the reverse lights do and the headlights do but they are on different circuits so that makes sense. I suspect it is the headlight switch that is the problem because both flashers are brand new and like I said I know the wiring is correct. Also I have good grounds for all circuits. One more thing I'd like to mention is that the hazards work but the the signals do not i know that the turn signal cam is good because I rebuilt the column with all new parts. Any help or thoughts would be greatly appreciated. Thanks Ryan.

[74challenger03]

did you check all the connections? pm SLOTTS ,he could tell you if its the headlight switch. Jim rebuilds all the dash switches and is a great guy. This is his e-mail   jsrestorations@rocketmail.com

[rcuda22]

I have checked all connections. Thank you for letting me know about him I will contact him!

[dodj]

There is a seven wire connector behind the driver's side kick panel. The 18 gauge black wire needs to have 12 vdc on it for your tail and park lights to work. Check there with a meter and you will be able to determine if the problem is with the dash wiring/switch or the rear wiring harness. 

[rcuda22]

I checked the voltage at the black wire and I'm showing 12 volts unplugged from the rear harness connector but once it's plugged in I show right at 3 volts on the rear harness side of the connector on the same black wire. Do you have any idea what could be causing this?

[Jamiez]

Most likely corrosion in the wires/connector.  If you have 12v on 1 side of the connector and 3v on the other then there is a resistance between them.  You can set most multi-meters to read resistance (ohms, or the little upsidedown horseshoe looking thing ). I would put 1 meter lead on each side of the connector and see what it reads.  Under normal conditions this would be a very low number probably less than 1 ohm.  Based on the numbers you gave, you will see a much higher number.

You might be lucky and it's just grime or corrosion in the connector itself.  In which case you can probably clean it and coat it with dielectric grease to prevent it from coming back.  If it's in the wire, then you're going to be replacing the wire.   I would also measure the connector end of the wire and the output end (which ever bulb it goes to) for resistance.  Again it should be a very low number...high number is bad.

[dodj]

Well you know it is not the switch now. I agree with Jamie, your connector probably has a bad connection causing the 9vdc drop across it.

You have proper fuses in the fuse panel? A fuse that is tooo large will sustain a short (not a dead short) for a while and high load will draw down the 12v, but will eventually burn wire insulation.

[HP_Cuda]

Resistance is futile... sorry had to say it.

Sounds like either you have to clean the back half of the wiring harness or buy a new one.

[dodj]