headlight relay

[GenevaPinz]

Hi all,

I think I pinned down my healight failure to the relay, but please let me know if you think I'm completely wrong (which is always a possibility when it comes to automotive electrics ).

My low beams simply don't work.

As the low and hi beams share ground, I dismissed a ground issue because my hi beams work fine.

I tested current at the relay's contacts: As hi beams are ok, I unsurprisingly could confirm that I have power from the red wire and from the hi-beam steering column switch (brown wire). I do have power on the white/black wire (coming from the main lights knob, and only when I'm it is on the second position), but not on the white wire (going to the circuit breakers for the low beams), so I believe the relay is the issue.

Apart from the fact that I welcome any dismissal of the conclusion I drew from my little serie of tests (any sarcastic comments included ), is there any aftermarket option other than the stock relay? I have nothing against OEM parts, but if you know of something more recent and reliable, please feel free to share.

[Jimm391730]

I have a couple used ones sitting around; when SoCal was in business I rewound some of them to operate on 12V for the RedBull trucks. They are really quite simple and easy to open, take a look inside and see if you just need to clean the contacts. But as I've never seen one that had the contacts fail, it is more likely the coil.

This relay is a "latching" relay, in that the coil only pulls in when the lever is pulled and you hear the "click - kerchunk" of the contacts changing, then the coil releases when you release the lever (kinda like clicking a ball point pen). There is a separate contact that supplies power to the high beams when the lights are off but you pull the lever for the "bitch switch". FYI, every time you do this you also change from low beams to high or back again, so if you turn on the lights and wonder why the high beams are on, now you know.

So if you don't get a click when pulling the lever then the coil is probably bad and it won't reset back to low beams. Open up the can and look carefully at the very thin coil wires:
You just might see where one has broken (usually from vibration over the years). If it is the wire that is going to the outside of the coil you can just unwind a turn or two, the coil has over a thousand turns and it won't notice a couple missing. If the wire to the inside of the coil is bad (the wire that goes up into the sleeving) then you are SOL.

Here are the terminals and what they are:

I might have the hi and low terminals reversed when I labeled them. 20-50 ohms is a good range for the coil resistance. Hope this helps.

[GenevaPinz]

Thanks a lot Jim

I did hear the "click - kerchunk" when testing (successfully) the hi beams, didn't hear it for the lo beams.

Your post with pics may be clear enough for me to gather enough courage and try open-heart relay surgery

[Jim LaGuardia]

Pull the can and lube the switch with WD40, I find this fixes most headlamp relay issues as they tend to get sticky with age.

[whitesik]

I'm dredging up this old post as I am having trouble figuring out my loss of high beams, right and left. No click from the relay when signal lever is activated so I suspected a bad relay. However, in reading this post, there is a comment that a brown wire from the steering column is the high beam switch. Well it just so happens I have a dangling brown wire with a spade connector coming from the steering column. . The problem is, my relay seems to have wires on all of its connections already. And, review of the color wiring schematic shows the brown wire as the horn wire. ( my horn works) Any help is appreciated and especially if the pictures of the relay connections could be reposted since they are no longer visible. I think will put a meter on that brown wire and see if activating the lever sends a voltage.

Thanks!!!

[whitesik]

Well I just could not let this go tonight so I decided to get the voltmeter out and do some late night testing. As it turns out, the dangling brown wire appears to be just a ground for the high beam switch. Or, at least grounding it gives voltage and the relay cycles giving high and low beams. This brown wire has a spade on it so it must clip into somewhere. Any ideas? If I can't find its real connection, I will just ground it somewhere.

Again, any input is appreciated!

[pcolette]

The brown wires throughout the truck are typically ground wires including the one connecting to the horn button. Possibly the loose brown wire you have found actually has a faint white stripe on it, in which case it is the lead from the high beam switch in the turn signal switch. It probably loosened up and fell out of the plastic connector(s) where it connects to its mate that goes to the relay. It would have a spade terminal on it.
This photo may help:

IMG_2462.jpg (375.57 KiB) Viewed 1938 times

[whitesik]

Thanks Paul, I will look again but I was pretty sure it was solid brown. The brown and white, according to the schematics, goes to/from the 31b on the relay to the high beam switc.. My dangling brown wire does come from that group of wires so I will check the connectors. It makes sense that it plugs into there but it is probably important to find the right one. I also need to follow that blue wire as it appears to be the one lighting the high beam dash light which also does not function. It appears to come directly form the #6 breaker along with the right high beam headlight.

Thanks for also being up late to help me!

[pcolette]

The wiring harness from the turn signal switch in my photo uses some different color wires because it is an Austrian switch, not Swiss.