510 Headlight Issue

[Cheetahking]

Hello - been slowly working on a problem on a '70 4door 510. Slowly - because it hasn't been of high importance, and because my back doesn't necessarily like being hunched in the engine bay (being 6'-6" has its issues).  

I have searched and understand the basics of the negatively switched headlight system of the 510, but wanted some input on direction before tore everything out and went through it. The car - stock, low mileage (90K??) - its in the transition era in terms of its wiring: has the older style relay with the separated plug, 3 wire fuse box, and has the red/red-white/red-blue harness for the headlights (white needle gauges).  

Symptoms - Low Beams work fine. Switch to high beams, and the drivers side works (both illuminated fully), and the passenger low beam goes dim, with the high beam not showing anything. I'm assuming a short or poor connection somewhere in that side.....

What I have done - took apart the relay - it was in amazingly good shape (the old design seems to be more weatherproof than the one in my '72). I cleaned the contacts. I didn't expect much here as the relay is obviously doing something. I do have a Bosch style relay that I could re-wire into the system if there is potential issue with the original relay - but would rather leave the wiring intact....

What suggestions can you give me as where to start.....nothing too stupid to throw out there.  

Thanks a lot in advance.

[banzai510(hainz)]

have you tried a new lamp first. or ck the connection on the 3 prong connector. They can have a burt metal connector. or see if carboned up. and wiggle connector.

 

or just remove the connectors from the lamps. then get a test light.

 ground the aligator end of the lamp. then put on the 3 prong connector. all 3 should have 12volts. then put on lamp then I think its only 2 will have power. then hights the ground moves and should be 2. but do this on both sides

 

 

the highs will be 12volts on both then when lever is pulled back one side goes to ground. so onley one side will have 12volts.

otherwise I say its good and clean the fuse box and swap out the fuse.

 

 

Most time its just corrossion at fuse box or at the connectors.  reseat the plastic connoctors at fuse box and at the lamp. or at the relay

[bananahamuck]

Mine used to do the one dim every once in a while,, and i was in a parking lot one time in the middle of no-where,  thumping on the relay and stuff,( again),, and some dude named Ron,,,,,,, walked over and fiddled with the wires coming out of the bottom of the fuse box.. and fixed it.... Not sure what he did but it was definitely on or in  the fuse box. At least for me it was

 

I later soldered in a Bosch type relay and the lights were brighter all around,, so i would do that as well..

 

Couple links i used to change to Bosch if you haven't found them already

 

http://www.the510realm.com/viewtopic.php?t=8226

 

http://www.the510realm.com/download/file.php?id=7553&sid=62eeb4374b91a7b0009c6e1430d04ce8&mode=view

[banzai510(hainz)]

bottom right side of the fuse box is the lamp fuses which go to the front. wiggles this or remove the connectors and clean. the white plastic connectors if not the lamp connectors or lamp

[Cheetahking]

Thanks - I will work through these and report back what I find.