70 Cuda Tail lights & side marker lights not working

[71340RT]

I drove my 70 Cuda to a Mopar cruise in party last saturday and left just before sunset. When I turned on my lights my lights on key in buzzer started buzzing. I pulled over to realize my headlights were the only lights working. I pulled the buzzer wire off and drove home with my 4 way flashers on. I have only checked the fuse and went ahead and replaced it even though it looked good. I'm not sure why the buzzer comes on when I turn the lights on but there has to be a issue somewhere causing it. My lights still don't work and I'm not sure where to start trouble shooting this problem or if someone has had a similar issue and what they found. My wiring harness is still the original for a 70 Cuda with ralley dash cluster and really has no splices that I  remember anywhere. I have been driving my Cuda for 3 years since it's restoration and have had no electrical issues at all and it just made a 300 mile round trip with no problems just the weekend before this happened and I used the lights all weekend.

[72hemi]

That's really odd. The only thing I could suggest is to start checkign grounds to see if some came loose or something.

[Moparal]

Maybe your hl switch went bad or pulled out half way. Or the ground screw loose to the switch panel

[MEK-Dangerfield]

The headlight switch was my first thought too. All the lights that are out for you, should be on when you turn the switch to the parking light position.


  Mike

[71 DEPUTY]

DOES the cig. lighter work??? it shares the same fuse as the marker lights.

check the headlight sw. connector- see if there is + 12 volt to the pink wire- if so then the sw. could be toast!

[71340RT]

DOES the cig. lighter work??? it shares the same fuse as the marker lights.

check the headlight sw. connector- see if there is + 12 volt to the pink wire- if so then the sw. could be toast!

I checked the cig. lighter and it does not have power to it. I have another headight switch but I'm not sure that is the problem. I forgot I was plugging in my dash light conection under the dash about a week ago and pulled the cig. lighter wire off by accident and blew the fuse putting it back on but I put a new fuse in then. I'll check things out more this weekend to see what I find.

[71340RT]

Ok I changed the headlight switch and the side marker & tail lights still do not work. I used a jumper wire at the headlamp plug to make the tail lights and the side markers work but they still do not come on. I'm not sure if this a ground problem or not but I thought they would come on with a jumper wire. I'm going to look at the wiring diagram in my shop manual and see if I can find where all the grounds are located.

[Chryco Psycho]

I would start tracing power , check at the firewall & see how far power goes

[71340RT]

The problem seems to be the road lamp relay as I pulled the wire off it late last night and everything works fine with it unplugged. I'm not sure if I fried the relay but I was at shelbydogg's house today and we could not get the relay to energize when we put power to it. I'm going to check out all of the under dash wiring this winter and try to see if I can find someone who can fix my relay as the only ones reproduced ar for 71 Cuda's and they are 4 prong and mine is 3. Everything seems to work fine now and I think I must of messed it up when I blew the fuse putting the wire back on the cig. lighter.

[71 DEPUTY]

mopar didn't use relays to power the parking lights.

at the headlight switch check to see if there is + 12 volts at the pink wire-if so then headlight switch is good.
if not- check the fuse boxlower right side- should be + 12 volts on both sides of fuse for being good- also check behind the fuse box for a melted/ bad connection.

Find the two back wires on the connector- with the headlight switch on check to see if there is + 12 volts- if none- switch bad
if so then there is a bad connection to the front and to the rear lights.

[ShelbyDogg]

He said that it is the ROAD LAMP relay. I drew him a diagram to wire in a normal newer style relay to get it to work. What we really need is the 70 Cuda road lamp wiring diagram. My 71 manual had the 4 pin relay shown but not Jeff's 3 pin relay. The 4th pin wnt to the dimmer switch for '71.  It must have been a supplement to the manual that came out later. Anyone out there have this '70 diagram?

His relay coil was open, but the way I see his relay, it had 3 pins. Pin 1 to the lights, Pin 2 to constant 12v, and pin 3 from the switch that supplies 12v when the key is on.  This should not have worked without a ground on one side of the coil.

Jeff, did road lamps worke before all this stated? 

[ntstlgl1970]

If you have a picture of the relay, could you post it? I may have one....

[71340RT]

Rob everything worked including the road lamps before I shorted out the cig. lighter. Here are a few pictures of the relay and I think the number on the housing reads 2889916 and is for a 3 prong plug.

[71 DEPUTY]

was responding to the orginal post of the no power to the lights- didn't read enough about the fog light relay pulled and now works- still sounds like a issuse with power feeding the circuit.

here is a road lamp diagram.

John Mac

[ShelbyDogg]

That is the same one from my '71 service manual.   The difference is that Jeff's relay has only 3 pins AND his switch only has 2 wires on it. That's why we need the diagram off of a '70 manual.

Jeff, now that I see the pic, your ground has to be from the screw mount of the relay. Look at your relay apart and see if there was a wire going to the housing tab to ground it. Take an ohm meter and check it between ground and the terminal with the single green wire.