Headlights only work on High Beam 87 Merc

[rsolis]

Hello everyone.

87 Grand Marquis 102,736, 45,000 Miles annually almost all of them at night.

About a year ago my headlights were flickering on and off but it was very random and infrequent. It increased and eventually they went off completely. Replacing the headlight switched fixed the problem.

A few months later the same thing so I just warrantied the switch but it didn't work and I only had headlights if I flipped the high beams on. Both the low beam and high-beams would work, as they should. Replaced the turn signal assembly switch fixed the problem. The green pigtail (see pics) was melted however I couldn't find one to replace is so I just jammed it in there at the advice of a guy that does car work for me.( I know, I know) It worked. That lasted about a month and it's happening again. I warrantied the switch again for giggles but this time it's not work. So right now I only have headlights when I use high beams.

I don't know where to start so any advice is appreciated. Below is all the relevant changes I've done to the car that could be related. I ordered a replacement pigtail and it will be here tomorrow but I don't wanna just replace that and have the problem come back. The pigtail is hot to the touch when beams are on.

The Headlights I have are Silver Stars H4651ST for both high-beams and low beams.

The alternator got replaced this summer. It it's not a 3G just whatever autozone gave me. I can get that information when I get home.

A side note and maybe it's related. I replaced the start solenoid because it went bad. It now acts up in the extreme cold. If it's really cold and I turn the key to start I will get nothing. No crank,no click. Silence. This will stop if I keep the key in the on position for a few minutes. The colder it is he longer it has to be in the on position but eventually it will start.

Battery is less than a year old.

I replaced my dashboard lights with LEDs. The green housing that goes around on the old bulbs was starting to crumble.

Lastly it should be noted that I drive my car for work exclusively at night, 5 days a week 8 hours straight. So the headlights are ALWAYS on. And if I'm out in the middle of nowhere so are the high beams usually. I flick the high beam switch probably more in a night that most do in a year.

The wire that is in the melted socket on the green pigtail is red and black if that helps any.

Hopefully you guys have some insight. I get instant notifications so if you reply it won't be long for me to get back to you.




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[His Royal Ghostliness]

The really hardcore melted section of the connector, what wire comes out of that? Bet it's the one powering your high beams, them things are 4x55W yet they're fed thru a single 14 gauge wire with like a 20ft long run. That setup makes for some nice voltage drop and heat generation, and you see the end result of the heat thing. What to do:

1) replace the green connector. As it sits right now it probably makes very lousy contact with the multifunction switch, which makes for more resistance and heat generation, which damages it even more. Yes it's a vicious circle, to put the kibosh on it you need to ensure excellent contact between the switch and the harness. Which will likely require some cleaning of the metal parts of the connector as well, the ends crimped onto the wire I mean.

2) install relays for your headlights. This should actually be one of the first things every owner of an older Ford vehicle should do, they all suck in that department.

3) install some nice driving lights. As long as they are of road-legal power level (55W per lamp) they are allowed to be used together with the low beams, and being that their beam pattern can (or at least is supposed to) reach past high beams range you may find out that you rarely get to flick between lows and highs aftwerwards. These will also need a relay, you can control it together with the low beams if you don't feel like running extra trigger wires (do not use running lights for trigger as per the law driving lights are supposed to go off when high beams are on).

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Regarding the melted dash lamps caps, that's also result of heat buildup, and perfectly normal after so many years of yse. Smmall LEDs run pretty cold, so since you already convered your dash to LEDs you will likely never have that problem again.

About the starter solenoid - this is the one on the fender, right? Pull all the wires off it and start sandpaper-ing the ring terminal on both sides. What's happening is you got two issues at the same time:

#1 is that your new starter solenoid is lousy, it should not stop working when cold and start again when warmed up.

#2 is that the warmth that makes the solenoid go again is a result of a poor connection between the 300 wires hooked up to the one big terminal - when you turn the ignition on there's decent amount of current going thru them wires, if the contact is so-so said current will start making heatm which is nice for warming up your solenoid and making it work again but it really should not be happening at all.

So warranty that solenoid, clean and sand all ring terminals on all wires hooked up to it, and if the nuts are brass you can sand and reuse them but if they're steel just go get new stainless ones, you need 5/16" coarse thread.

[VicCrownVic]

I can't think of anything to add to what HRG said, but if you're still in the Waterford area we have a few members not too far from you; I'm in Shelby Township near Mound & M59.
I've done the headlight relay mod on my '91 MGM if you ever want to see it. I made my own harness but there are some harnesses marketed for older Chebys, on Ebay and maybe places like Summit, that I think would work with minimal modification.

If you're ever interested in hitting up some Metro Detroit Junk Yards shoot me a message. DerekTheGreat, AshleyTheGreat, and I can often be found at the JYs.

[86VickyLX]

Red/ black stripe wire is for low beams. Go to a yard, grab another connector and cut that wire out and swap all of your other wires onto the new connector. Then do yourself a favor and relay your headlights. This happened to me but on the high beam wire (Light green/black stripe) but not as ridiculous as that. Possibly because I could smell something burning whenever the high beams were on. The multifunction switch contacts inside are probably dicked as well, but if you can probably get away with relaying the headlights, as the current won't be as great powering a little relay instead of the lamps themselves. The headlight switch itself tends to burn out as well.

[gadget73]

Wiring on these left something to be desired 30 years ago, and it has not improved with age. Relays are little magic pixie boxes that do good things.