1993 K1500 Blazer Head light trouble

[Metrodps]

OK so here we go I have a gremlin under the hood again! I drive from Montrose to Colona (about 16 miles) on low beams hit the high and they come on then go out. I lose both low and high beams. I put flashers on and slow down to stop and put the low on and in a second or two they come on. This is the second time in just about the same distance of driving.

I drive all the way back to Ouray ( about another 16 miles) on low beams. I get to road going up our mountain and hit high they come on then go out click low and in a second or two they come back on.

Totally at a loss on this do the newer trucks have a relay for the high beams? Old school lights I know these darn newfangled trucks are a riddle wrapped in a mystery inside an enigma, but perhaps there is a key. Might some one here hold that key?

 

[Slapperbar]

The switch is probably overheating. There's a big heat sink in it. Big guess.

 

[Z71paramedic]

The switch is probably overheating. There's a big heat sink in it. Big guess.

x2. My 93 K1500 had that exact thing happen.

 

[Metrodps]

The switch is probably overheating. There's a big heat sink in it. Big guess.

Dash Switch or the one on the stalk? I'm guessing you mean dash one.

 

[Metrodps]

OK this is back of dash switch. The heat sink is for the dome and dash dimmer (99% sure). So are you saying I need the toggle switch or whole thing?

the rear of whole thing.

the light only side.

 

[Slapperbar]

Prob., most likely, the headlight switch. I forgot it was the dimmer that had the heat sink.

 

[Metrodps]

Seems like it would be in the turn signal/wiper/hi lo switch. In an old style (on floor) I would say it was the dimmer.

 

[Fordum]

OK, for a long time now, all headlights have to be fused with a resetting circuit breaker.
On Fords, its often built into the main headlight switch. But, some trucks have them on the fuse panel. If you see a small black box plugged into a fuse socket, then its probably a breaker.

Sounds like you have a dead short in the highbeam circuit. When you go to highbeams, the breaker trips, and resets after it cools off.

Often when someone puts on aftermarket headlights, they will draw more than the rating of the breaker, and will flash on and off when driving.
That is when you have to add relays.
Also, the breaker can get old and weak, and make the lights flash.

But, in all of those cases, the key is slow speed. It happens after the lights have been on for a while.

Since yours is doing it pretty much instantly, then it sounds like you have a dead short in the highbeam circuit.
Check the wiring, and try unplugging the bulbs. Unusual to see a bulb short out, but it is possible.

 

[Fordum]

Here is the schematic of a light switch up to 87. Don't have a newer schematic that shows the switch in detail.
Looks like its a 16.5 amp breaker inside the switch.