I have an aftermarket headlight kit on my '74, came with the car. I was recently doing some work under the dash and I noted that when the high beams are on the pigtail wires from the floor switch is getting really hot. I thought it might be the switch so I replaced it with a new one (and a new pigtail). No difference. In fact, when I went under there today I noted that two of the wire connectors I used to splice the pigtail into the harness wires were burned. They are hot enough that if I run the high beams for more than a minute they will burn your fingers if you grab them.

I think the simple solution is to change the wires in the floor switch connector to a larger wire but I'm worried I am just masking a larger problem.

Is this the right solution?

UPDATE: Not sure if I was clear but I noticed last night that the BLUE WIRE was the one heating up. I have the relays and the fuse holders and I was planning to wire this up over the weekend. Will this solution take the load off the blue wire? I thought it was designed to work for the green and tan switch wires...

QUESTION: Can I run both green wires into a single relay? They are already split coming out of the firewall connector

Thanks,
Dan

 

HL relays might be the way to go.
Are all 6 of your elements lit up or only 4 like stock ?
Do you notice the HL switch getting hot ?

 

Hi Roger,
I have not noted the switch getting hot, just the wires coming from the connector. Good question on the number of elements. There are 4 lights up front with the high beams on (like stock) but I am not sure how many elements inside are being lit. I will have to check that.

 

There are two reasons wires will get hot. Most common is a poor connection, high resistance, at or near the heat. If your connections are clean and tight then you are left with the second cause, too high a load for the size of wire. I would almost guarantee that your after market headlights are drawing far more power than the oe lights and the wiring and/or the device can not handle the load.

You want to go to a headlight relay system. That way the current through the switches is only a low amp control current. The current supply wiring to the relays and the wiring from the relays to the lamps should be a 12 ga wire at least. You will likely find your headlights brighter as well as your car less likely to burn to the ground.

Steve g

 

I'm not sure I really understand relays, although I have them on my electric fans. I feed power into the relay separately and use the switch purely as control?

Can anyone recommend a relay that would be correct for my application? My headlights are way dimmer than they should be, btw.

 

There are many threads on CF about headlight relay setups.

One of our younger guys brought up an interesting idea that go my attention.
He wired the HL switch to control low beams only, disconnecting them from the dimmer.
Then he wired the dimmer with a direct hot and used the dimmer switch as an on and off to control high beams only.

 

Here's one with some good links.
http://forums.corvetteforum.com/c3-t...tml?forum_id=3

 

would this relay be wired tot he headlight switch in the dash or to the beam selector switch on the floor?

 

If I remember right the green and tan from the dimmer just go out to the relays and tells them when to turn on and off. They would carry very little load.

 

Here is a diagram of what I did, you may not want to go this way, but the diagram may help you understand how a headlight relay harness works.

First, I didn't want both the left and right side on the same relay. I didn't want to be driving at night, and have to worry that something going wrong with my harness would take out both my headlights - so I created 2 separate harnesses, one for each side. So the diagram below is for one side only.

Also, I did not want to splice into the stock harness, so I purchased pigtails that would plug into the existing harness, and I spliced into the pigtails. The pigtails I bought are hear - http://autolumination.com/connectors.htm - look for "H4 9003 P43t Ceramic Male to Female".

I bought the relay sockets from Frys - www.frys.com - search for "relay socket". The relays you can find at any auto store, make sure that the relays are headlight relays, and they have 2 '87' (normally open) connectors, and not 1 '87' and 1 '87a' (normally closed).

You can see that the load for the headlights is no longer carried over the stock headlight wires (green/tan/black). The stock wires are only used to provide a small amount of current to control whether the relay is open, or closed. The load for the headlights is then carried over new heavier gauge wires that are hooked into the alternator.

 

awesome! thanks guys. I think I got it.

 

UPDATE: Not sure if I was clear but I noticed last night that the BLUE WIRE was the one heating up. I have the relays and the fuse holders and I was planning to wire this up over the weekend. Will this solution take the load off the blue wire? I thought it was designed to work for the green and tan switch wires...

 

Yes, the blue wire will then only carry the current required by the relay coil(s). You'll add a new higher capacity wire/circuit to the relay that will feed the lights. Remember to fuse this new feed.

Jim

 

I think just one more question:

The green wire is split at the main firewall connector so I have 2 green wires and 1 tan wire in the engine compartment. Can I run both green wires into a single relay for the high beams ?

 

Yes 1 green is all you need if you are using 1 relay for low and 1 relay for high.

 

Hi All,
Any issues if I pull relay power from the bus bar? Looks like there is a wire in every "slot". Couldn't tell you what they all are off hand.



For the high beam circuit my plan is to run a single green into the relay as the trigger wire and both greens out of the relay from a single connector to the lights... i am now wondering if I need to use larger wires from the relay to the headlights to accommodate more current. It has been suggested, in this thread even.

Thanks,
Dan

 

Excellent news! I jumped the wires for the high beam circuit and everything worked perfect! No hot wires from the dimmer switch, brighter lights, all seems well. i will complete final wiring shortly.

Thanks all for the help!