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Headlight relay trouble

R/T 71

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I did a headlight relay conversion on my 71 Challenger, and encountered some problems. Whane low beams are on, the high beam headlights have an ever so slight illumination. When the high beam is initiated by the dimmer switch, the highs (inside units) are very bright, but the lows (outside units) are dimmer than they should be. I have done everything to isolate the high relay from the low, but those issues still persist. I've even used separate grounds thinking that could be an issue. The only thing common to the relays is the power source. I followed to a T the schematic I found on one of the E Body sites. Could I have a bad light switch or dimmer switch? Running out of ideas.
 

Challenger RTA

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With out knowing or seeing how it is wired. fist thing came to mind was the headlight dimmer sw as you said. Use 2 test lights plug one into low and the other into high of the original wiring.see if there is the same effect. also sounds like a bad ground feeding back. might be dimmer sw.
 

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The other thing to do is connect to the battery temporary and see if relay circuit works correctly. This will narrow it down to start.
 

Challenger RTA

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Did you use 9007 or 9004? that might be the problem. the grounds on the bulbs are different.

9004-9007-2-1.jpg
 

Steve340

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The problem is likely to be in the low beam side from what I gathered from your post.
When on low they are earthing through the high beam that is why the highs glow up a little bit.
And when on high the low beam is dim because the high beam uses it's earth and nothing left for the low so they are dim.
 

tonysrt

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I had a similar problem and found it to be a bad ground. Make sure all the headlamps are well grounded. I used an ohmmeter to make sure I had a good ground with each ground and there was 4 ground wires one to each of the 4 headlamps and of course the relays are grounded.
 

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If you don't find the the dimmer sw is bad.Take note the 2 smaller wires as you probably know are the grounds for the head lights. Check for good clean connection and not hard brittle wires. Or broken wire. also the battery ground. actually feel every inch of wire for hardness.It means it's burnt. Battery terminals actually become corroded an inch or more were you can't see it. Get the lugs and terminals to shine clean clean clean! Just help some one fix their car that sat for a year or more. motor was changed. they swapped coil,wires,injectors,crank sensor,cam sensor,computer. I keep telling them it is a ground! Went and looked at it they cleaned the ground. NO It has to shine like a new penny.I cleaned it it fired right up. Clean Clean Clean all connections. Stat with the grounds.
 

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R/T 71

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Here's the latest. I cleaned all the ground areas and reattached all the ground wires. Same thing - faint illumination of the high beams on low and dim low beam when high is activated. So I grounded all headlights to the battery and got the same result. Stumped. So is is the dimmer switch, one of the relays or the headlight switch that could do this? It appears current is feeding back somehow.
 

Challenger RTA

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You said you tried relay circuit and it worked fine. Have to move on to test 2. plug in 2 trouble lights : one into low and the other into high of the original wiring.see if there is the same effect. check each socket. Did you try the trouble shooting each power connection to ground. can also be checked at firewall. you can unplug bulkhead connector and jump power to 14 and 15 to see how it works.

front_end_lighting_web.jpg


Harness schematic.jpg
 
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R/T 71

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I think I have found success. First, the polarity on the Wagner halogens was contrary to everything I had read until I did some more research. So I fixed that. Then I realized that the low beam relay was only passing 6 volts through it. A new relay fixed that. The only thing I see as an issue now is the relays do not have an output to the load side that equals the battery side. I'll get new relays and make sure grounds are properly prepared. Thanks to all who chimed in. I'll always know what to look for now when a situation like this comes up - again.
You said you tried relay circuit and it worked fine. Have to move on to test 2. plug in 2 trouble lights : one into low and the other into high of the original wiring.see if there is the same effect. check each socket. Did you try the trouble shooting each power connection to ground. can also be checked at firewall.
 

Challenger RTA

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The way you described you situation it seemed like the 9004 9007 bulb mix up. the pin locations are different. Where the Wagner bulbs made in China? Hope it all works out for you. seems like you know what you are doing or you would't have done it. Something or someone throw you a curve ball. Thanks for letting use all know so were not pulling are hair out!
 
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