Hi everyone, my headlights on my '77 Toyota pickup recently stopped working. I have no high or low beams but the running lights do still come on.

I've search this forum and found the culprit could be a handful of things
-headlight switch
-headlight relay
-corrosion
-alternator

I'm going to have to dust off my manual on how to use a multimeter so I can hopefully narrow it down.

I wasnt able to find in my Chilton manual where the headlight relay is located. Please see my attached picture. Is this my headlight relay?

Looks like both the headlight switch and relay are going near impossible to find.

What have people done to replace those items. Are there any alternatives?

Any feedback is greatly appreciated.

Thank you

 

I just read my ground could also be the culprit. Since the headlights are grounded at the mounting points, one bad ground shouldn't make all the headlights not work, correct?

 

Does the relay still click when turning the headlights on or off? I've had a relay that clicked but was faulty before pertaining to headlights. For the electrical looking box in your picture, put your finger on it and turn the headlight switch on and off and feel if it clicks; if it does then congrats you found it. Are any of your lamps breached to the atmosphere (i.e. full of moisture when it's damp out)? Couple factors here.

Headlights are run in parallel so even if you have one bad lamp out of four, three would still illuminate excluding the bad one. Wouldn't hurt to check the grounds for any suspect lamps for corrosion, but I'm not familiar with the pre-1979 trucks by a good margin.

Hopefully some of this helps!

 

I appreciate the response. I'm not getting any clicking from a relay when activating the switch.

I just removed the switch a little while ago and going to see if I can figure out how to bench test it with a multimeter.

I'll also be checking all my grounds. Hopefully I'll be able to make some progress soon.

Thanks again

 

Well I found my headlight relay. On my '77 it's locating in the engine compartment and not under the dash. It looks like the item I pictured below.

The relay clicks sometimes but the headlights still don't come on. I have to wait several minutes before the relay will click again. Does it sound like the relay could be the culprit? I'll have to do some research and see if I can bench test it.

Thanks

 

I figured it out. It ended up being corrosion on the relay connections (See below). Cleaned them off with sandpaper and the lights came right on.

 

Good work!

That relay looks a lot like the same headlight relay used on my 1989 toyota van; similar issue there too (seemed the lights were pulling too much current and semi-melted the socket and made the relay go bad)

 

You might want to test the relay and switch connections with a multimeter first sometimes it’s just corrosion or a weak relay causing the issue. Check This Out

 

Any updates?

 

Not too sure, though as I said previously the relay for his headlights looks similar to the 3-pin relay used in my Van's headlights (which had the same issue as described)

The 3-pin relay for the lights was also used in a few other toyota models (PART NO# 90987-01003 relay, light control) across the years but i'm not positive on one for the earlier twin sealed beam models.