1975 Headlight troubleshooting (1 Viewer)

[bhsdriller]

Everything works except the headlights on both sides. Brights do not come on when you pull the lever on the wheel
Running lights, blinkers, tail lights, brake lights everything is good.
Just happened recently.

Have searched alot. Headlight switch looks good internally, contacts are super clean.

Everyone saying check the grounds, where are the headlights grounded? That's one thing I couldn't find a clear answer on
What can constitute a bad dimmer switch or even something to check?

 

[bhsdriller]

Switch turns on the cluster lights inside and I can rotate to dim as well

 

[73FJ40]

The OEM headlight socket has three wires, high beam, low beam and ground. The ground is customarily a white wire with black trace.

Use your volt meter to check for volts to battery negative terminal from the high low connectors and continuity to ground for the white/black wire.

 

[pb4ugo]

When my head lights dont work, I 1st check and clean the contacts in the fuse box. A lot of times I just move the fuse back and forth in the holder cause it happens often and its usually dark outside. Sometimes the fuse will test good, but not make a good contact to the box contacts.

 

[bhsdriller]

I'll go through and check the voltage and ground continuity.

Fuse box is brand new so that shouldn't be a problem.

 

[bhsdriller]

No voltage to the headlight plugs, either high or low wire with key on and switch pulled.

I can do a jumper from the battery to the headlight and they work

 

[73FJ40]

Time for a look (and voltage test) at the high beam switch on the steering column.

 

[fjwagon]

I agree on cleaning the fuses, just disconnect the battery terminal. Clean terminals and reseat connectors are easy things you can try.

 

[fjwagon]

Sorry for being vague, anyhow, when you remove the ground cable on your battery, remove the headlight fuse and clean the ends also clean the holder with a fine wire brush. While you there clean the grounds going to the chassis. Everything on the fuse holder assy are for the positive side of the circuits.
You can also find the relay for the headlights and Reseat the terminals. Again, there may be some grounds tied to chassis nearby, it would not hurt to clean them as well.

When it comes to grounds there are 3 types, on a land cruiser, we have chassis grounds and than we have returns for circuits. Some circuits will share the same in the same location since we have one power source(12v). And we don't have a third, earth ground unless it's on its side . So without a drawing you can follow these color coded wires around but it will easier and faster if you have schematic drawing. You can do continuity checks with a test light or a multimeter. I have owned several 40s for many years and basically what I have found is cleaning and reseating will clear most problems but not always but most generally. The connections will oxidize overtime and will eventually need cleaning. Good luck.

 

[73FJ40]

OP stated:

Fuse box is brand new so that shouldn't be a problem.

So, is the fuse still good or did it blow on first activation?

When you installed the new "fuse box", was it OEM or something aftermarket. Are the wires to the fuse box connected in the proper locations?

Just thinking out loud....

 

[bhsdriller]

OP stated:


So, is the fuse still good or did it blow on first activation?

When you installed the new "fuse box", was it OEM or something aftermarket. Are the wires to the fuse box connected in the proper locations?

Just thinking out loud....

Brand new unit from city racer. Fuse is good and doesn't blow. Gonna check for voltage on the plug coming off the steering column tonight

 

[bhsdriller]

Have to drive it tomorrow so wired in a separate switch, fuse and relay just to turn them on/off for now. Stock switch still turns on everything else.

Will check the other things and update

 

[kerplunk]

Fuse box is brand new so that shouldn't be a problem.

Have these lights worked since this brand new fuse box was installed?

 

[bhsdriller]

Have these lights worked since this brand new fuse box was installed?

Yep they've worked up until a few days ago

 

[bhsdriller]

Time for a look (and voltage test) at the high beam switch on the steering column.

No voltage to the HL or HU coming from the steering column dimmer switch