Team Chevelle banner

Wiring issue on 70 El Camino

2K views 19 replies 5 participants last post by  Dean 
#1 ·
I recently installed a new Autowire wiring harness on the firewall for the lights and engine. Come to find out that as soon as the battery is connected all 4 headlights go on. I removed the headlight switch thinking it had a problem. Headlights still coming on with battery being connected. Anyone have an idea? I never changed the horn relay.
 
#2 ·
Check the wiring at the switch plug, its probably wrong. You won't be the first person to get a harness that's not correct. Call AAW if you need tech support to back their product.
 
#3 ·
This may seem trivial but, is the headlight knob installed? When you remove the headlight knob, the lights will be on. I have installed tons of American Autowire harnesses and never had any issue with something being done incorrect with their product.
 
#5 ·
With the headlight switch being unplugged, the power going to it cannot pass out to the headlights SO I'm thinking with you replacing the wiring "could" the ground from the headlights by the battery mistakenly have been connected to the battery fusible link junction block ?. Maybe if the ring terminals are the same size things possibly got connected wrong ?.

I know this sounds goofy but let's say this happens and now power is then sent up the ground to both the low and high beam filaments on that side of the car and then travel over to the other side lighting them up and then the headlight ground on the other side is grounded like it should be to the radiator support.

Jim
 
#6 ·
Great idea Jim! I'm thinking the same thing! Although i'm not using the junction block that wire is connected right to the positive wire coming off of the side post positive cable. I'm thinking its getting power at the horn relay. OR when the harness was made there's a wrong connection at the plug. When I installed the harness I never installed the headlights to catch this while the fenders were off. I like your idea of 12 volts going through a ground though. No parking lights or marker light bulbs are in yet. There's red and black wires that go to the hot side of the relay, I'm betting one of those should be a ground and had the wrong end put on by mistake.
 
#10 ·
I just had to wonder since the only way power should get to the headlights is from power supplied to the headlight switch and if it was not even connected I thought what could have gone wrong. I just remember on my 68 behind the battery on the backside of the radiator support there is a bolt with 3 wires going to it AND not too far is the junction block stud. One could very well make wrong connections. I remember years ago working on systems for Delco and Rockford Fosgate and ask the GM engineer why there were SO many different plugs in a cars wiring and he said that way no one can plug things together wrong.

It also sound like your issue was on the other side by the horn relay. I didn't even think about that side BUT it makes sense.

Shaking my head, can't see how that would happen... but Murphys Law is always right.
Come over to the dark side of selling and installing car audio and you will be exposed to all kinds of things you would not think were possible but are.

Jim
 
#12 ·
I had to think about it too a few times but here is my thinking:

On let's say the right side of the car the headlights are grounded and this ground goes to both filaments in the one headlight that has the high and low beam and then over to the one headlight that has just the high beam filament.

Now you have a green and a light tan that go over to the left side headlights and there they make connections to those two bulbs and then just a single green and light tan that then goes to and through the firewall to the headlight dimmer switch, the headlight switch and also the high beam indicator light in the dash.

Now on the left side headlights normally you have those headlights grounded but in this case the ground went to power on the horn buss and now power is sent up the ground, to and through those headlights bulbs, then the power continues to and through the other bulbs on the other side and then there is where it ends in a ground for that side headlights.

Basically you have sent power up a a common ground then into some headlights and then power into the other headlights and then to a ground. The lights on one side are in series with the other side.

Jim
 
#19 ·
The power being fed into the left ground wire is going to and through all of the bulbs so it will not matter as they would stay on whether the headlight switch was plugged in or not.

In the diagram I modified it shows in red full power going into the left side headlights and then once power goes through the filaments the power is reduced and show in orange and then once power goes through the right side headlights and then to ground, the power is used up.

With this setup you would then have reduced power being sent down the tan and green headlight wire into and through the bulkhead connector down to the dimmer switch and then out of the dimmers blue wire up to the headlight switch. At the headlight switch connector if the headlight switch is not plugged in then this is fine. Nothing plugged into the connector will not have any of those wires in the connector being connected to anything.

Now if the headlight switch was plugged in and off, then it would be just like having the switch not plugged into the connector. No connections are being made.

Something would change though with the headlights if the headlight switch was turned on and the left headlights ground was still connected to power as the left lights due to how much voltage is being fed into the left headlight ground wire and then how much less power is being delivered from the headlight switch. Chances are the power from the headlight switch would be less as shown when people add headlight relays and are getting power closer to the battery and the headlights are brighter due to less connections and shorter wire lengths.

Jim
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top