Headlight Switch or Headlight Relay bad?

Had my headlights on the other night and smoke came out of the column. Turned the truck off and the headlights, but, headlights don't turn off.

And, the relay is buzzing like mad? Not sure why a bad relay would cause the switch to smoke?

Nothing has been done in the column. I am the original owner.

Pulled the column apart and nothing melted in the wiring harness.

Thoughts? New switch or new relay or both?

 

The relay got stuck 'on' after circuit el was energized through the switch. The contacts in the relay arced(welded) itself closed or on and thats why key wouldn't turn it off.
I would start with replacing only the relay. Where is that relay located?

 

Does column light switch smell burnt?

 

I think those replays are only like $25 (OEM is probably like $500, lol). vs. the column switch which is rather more expensive and more involved to replace.

I'd start with the relay.

 

Buzzing sounds to me like the relay is trying to switch, but can't get enough current through the coil to hold it, which would mean its not getting enough current from the switch.

Between that and the smoke from the column, my gut says its the switch.

 

That very well could be as well. Good call. Switch is on ground side to, huh? I think switch now too. After reading your comment. But should be able to smell it as well.
But also the relay was stuck on while key was off too. Or switch was stuck on allowing relay to try and function.
Yeah I think switch too

 

Time to break out the meter !!

Not sure if the Circuit has changed for OP`s year but on mine (2000)

The only way the relay coil is energized is with the head light switch closed allowing the circuit to go to ground and complete the circuit.

A mechanical failure or voltage spike through the switch .

The contacts in the relay most likely did not like the bouncing .

 

I gotta guess the switch too. That perpetual smell of burnt plastic. The stalk on eBay is/was $31.

In the meantime. Definitely test the relay with a multimeter.

Headlights are overrated anyhow...

 

Appears that I jumped a short in the switch. See the burned spot highlighted in red.

Replaced the switch with a new one and no headlights?

Put the old switch back in, headlights come on and same buzzing from the relay. Now what?

 

Can you probe for voltage where that relay plugs in? You want to see 12VDC coming into that relay. If you have the 12VDC at relay that means switch is working and allowing the circuit to complete and energize the relay. Relay could be failing.

 

To bad the picture is to dark to see.

At this point I would pull the relay and test see if you get the buzzing .

Why did the new switch not work bad out of the box ??

The switch was new or used?? correct for your truck??

 

Well, I must have 12v at the relay if, when I put the old switch back in and the headlights go on and the relay does the same old buzzing?

The switch is brand new, aftermarket though. Actually bought 2, thinking one of them was bad out of the box. Always a possibility with the aftermarket stuff.

I cleaned the contacts in the old switch where the short happened and plugged the old one back in and like the new switch, no headlights...

Gonna try the new relay route, unless I have a short in the wiring somewhere that caused the short in the switch?

 

Sounds like you're on the right track. I guess I'd test before replacing but replacing is easy and cheap enough I guess.
But if I were to try new parts, that would be the next new one I try, the relay.

 

Hate to keep coming back to you guys on this one...

New relay and still no headlights. ALTHOUGH:

Pull the stalk back and the high beams work and high beam indicator comes on.

Push the stalk forward, no high beams and no indicator light?

New bulbs or am I searching for a ground short in the lows? Just don't get why the highs work in flash mode but not in hold?

 

The lights work in Flash because two different circuits to get to the head light relay .

From your results the one for the flash circuit is working the other is open.

Arced and burnt pins in a connector or junction block

By any chance does this truck Have Daytime Running lights ??

The head lights are switched ground.

It is a pain to get at the plugs but testing for voltage is not hard once they are removed

You have checked the fuses none are open??

Do the tail lights light up with the switch ??

Have you looked for burnt wires causing a open circuit

Pain in the butt to trouble shoot from far away.

Best of luck

 

At the end of the day, was the body ECU that went bad. Which is built into the under dash fuse block. Multiple names for it. Grabbed a fuse block out of a yard. Worked just fine.

 

Glad you got things working .

Any idea what caused it to happen?? Loose connection Evil Rodents ??

 

Just had the same(ish) issue with my ‘05 (175k). Headlight relay would engage as soon as battery was connected, effectively causing headlamps to always be “on”. Fogs, running lights, and brights all worked fine. So just pulled the fuses for the headlights and ran during the day while waiting for replacement parts to come in…

Replaced relay ($15): No effect - relay still threw immediately upon battery connection.

Bought a new stalk switch ($60) and pulled out the original: Both passed continuity test, and the relay still threw regardless of which switch was wired in.

Disconnected the fuse box computer: Lo and behold relay stayed disengaged.
Replaced fuse box with eBay salvage ($80): Issue resolved

No warning, no discernible cause, just happened. Thanks to RacerP’s post about the body ECU i was able to at least narrow down to switch or ECU. Would have been a long, frustrating, and probably expensive road without that direction.

 

Thanks for posting this.

Just as a follow-up as I am chasing down another issue on this 21 year old truck w/ 320K miles...

I was going through testing and redoing ALL of my under hood grounds. The ground on the passenger fender, under the ABS was toast and probably the source of my headlight issues.

I cut the old ring connector off, stripped all the ground wires back to install a new ring connector and sure enough, the ground wires were all burnt under the wire insulation.

You might want to check your grounds