No Low Beams - What to check next? (1 Viewer)

[lovetoski]

On my drive home from River Shiver my low beams stopped working. Kind of a pain in the dark and rain, but re-aimed my driving lights and kept going.

Prolly should get this fixed...

• High beams work fine.
• I have a Slee aftermarket harness installed. (It's plugged into the Right-hand OEM headlight socket.)
• Fuses are good.

I've used a test probe on the unused drivers-side OEM headlight socket and here's what I've found so far...

1. The R-W wire from the OEM relay and fuses to the OEM socket is good - test probe lights up when switch is in low beam position.
2. With the headlight switch in low-beam position, when I ground the R-Y wire on the OEM headlight socket with the test probe, the probe doesn't light up, but the Slee relay's kick in and the low beams turn on.

Found this from 60wag
<<There's one relay that provides power for both low and high beams. One fuse for the left lamp and one for the right. If the high beams work, the relay and fuses are good. The dimmer switch on the stalk picks which element in the bulb to ground, high or low. If the low beams aren't getting a ground, its either the switch or the wire between the lamps and the switch. You don't have an aftermarket headlight wiring harness on there, do you?>>

I'm not sure what to do next. The two options 60wag lists make sense. But given the test #2 I did above, it seems like my switch is OK, and I've lost the ground? Or maybe I'm confused...

Any advice is appreciated.

 

[Rig of Mortis]

Here's a potential easy fix, or at least a test. We had a similar problem after a water crossing but this effected the two rear tail lights. We checked the fuses, wiring, tons of diagnostics, until this old drunk 'Cruiser head stumbled by an muttered "Did ya check the bulbs?" - Both of them had fried upon hitting the water. What are the odds of both at once?

...so, have you tried swapping out the bulbs as a test?

Might be worth a try.

 

[lovetoski]

...so, have you tried swapping out the bulbs as a test?

Both bulbs work, high and low. Boy I wish it was that easy though!

 

[lovetoski]

Been thinking about this today, and am guessing that the problem is in the multi-switch on the steering column. Since it's a switched ground, if the switch is failing, it won't ground out the circut. When I ground the light through the OEM harness plug the lights work...so I conclude it's a ground problem.

Let me know if any other thoughts...otherwise I'll post back what happens.

 

[Godwin]

I think someone posted a similar problem and the solution was to disassemble the switch and clean it.

 

[overhanger]

Been thinking about this today, and am guessing that the problem is in the multi-switch on the steering column. Since it's a switched ground, if the switch is failing, it won't ground out the circut. When I ground the light through the OEM harness plug the lights work...so I conclude it's a ground problem.

Let me know if any other thoughts...otherwise I'll post back what happens.

Negatory on the switched ground. Toyota switches the positive on our trucks for on/off operation. Think about the problem this way and maybe the anwer will come easier. I don't know what the answer is but wanted to redirect your thinking.

 

[lovetoski]

I think someone posted a similar problem and the solution was to disassemble the switch and clean it.

Ya. Read it. It influenced my thinking for sure. Doesn't sound toooooooooo hard...

 

[lovetoski]

Negatory on the switched ground. Toyota switches the positive on our trucks for on/off operation. Think about the problem this way and maybe the anwer will come easier. I don't know what the answer is but wanted to redirect your thinking.

I'm confused...I thought that Mr T used ground-switched instead of positive-switched. I've studied the FSM, and it seemed that ground-switched was the logic in the diagram also. Not claiming to be 100% positive on this though...

 

[60wag]

[*]With the headlight switch in low-beam position, when I ground the R-Y wire on the OEM headlight socket with the test probe, the probe doesn't light up, but the Slee relay's kick in and the low beams turn on.

The RY wire goes to the high/low switch in the stalk. When grounded by the switch, the low beams should come on. I think your problem is in the switch.

Also, I found a wiring diagram here on Mud for a 1988 60(62?) showing the 4 lamp setup. It appears to be wired the same as the round two lamp setup in the earlier 60s: Relay supplies the + and the stalk switch supplies the ground.

http://www.ih8mud.com/tech/88lc-wire/88lc-wd1.gif

 

[lovetoski]

The RY wire goes to the high/low switch in the stalk. When grounded by the switch, the low beams should come on. I think your problem is in the switch.

Confirms my hunch...diving in tonight...

Thx all!