How does the brights in the turn signal switch work (1 Viewer)

[arcteryx]

I am trying to resolve a low and high beam issue on my 73 40. With 2 switches, the low beams work but the brights do not (switch A). With the 3rd switch, the high beams work but the low beams do not (switch B). I have looked at each of them to see how the switch works mechanically but must be missing something. Below is a pic of one of the switches and how I believe it works.

What is odd, is if I use switch B and it is on low, if I push where the red arrow is, the low beams come on. I don't believe there is any metal on the back of the white plastic piece.

So who knows how this should work? I can bend the arms/tabs accordingly.

 

[wimberosa]

Don't take what I'm suggesting as knowledge....but the contact points you show and what I see in the diagrams seem like they
are logically correct. Have you looked closely at the fork (upper part of your pic) and the wiring connections there? Seems like if you've applied pressure at the red point and it suddenly worked on low...then there may be a poor connection in the upper part as opposed to something at the lower contact.

 

[Cromagnon]

Try "burnishing" the contacts with some emery cloth, the finer the better. Please do not use sandpaper. If you have a contact burnishing tool that would be best. Also check the electrical contacts that the metal strips terminate to and clean them also. Look for cracked insulation, insulators and broken crimp connections. Let us know what you find.

 

[bikersmurf]

When I was rewiring my headlights, I added a 30 A headlight relay connected to that switch. It’s now wired so low beams are wired to the normally closed circuit. That way only one circuit in the dimmer switch is used. Also should the switch fail the low beams will come on. The load on the dimmer is also eliminated minimizing electrical ‘wear’ on it.

 

[arcteryx]

You have a pic or diagram on how you did that?

 

[bikersmurf]

I don’t have a pic or diagram, so I’ve borrowed this similar one and I’ll try to explain the differences.

30 - Headlight Switch
86 - High beam switch (same)
87a - 12+ to the low beams of headlights
87 - High beams of the headlights
85 - Vehicle’s ground

In this configuration the dimmer switches’ terminal connected to the ‘bar’ that moves would be connected to 12+. When the dimmer switch moves to high beams the positive trigger will cause the relay to switch to high beams.

Alternatively, 86 could be connected to 12+, the bar in the dimmer switch connected to ground and high beam terminal of the dimmer connected to 85 (negative trigger).
Really
I’d recommend using whichever (+/- trigger) is closest to OEM, I can’t remember how Toyota did it originally. I’m leaning towards negative trigger, but I’m not sure for the headlight circuit. @Coolerman is the wiring guru... I wired mine 20 years ago so it’s not fresh in my mind.

 

[bikersmurf]

This sketch stolen from the web may take some of the mystery out of headlight relays. So long as the relay has power across 85 & 86 the switch will close.

 

[arcteryx]

Thanks for the diagrams. I took apart a switch and cleaned it. I also picked up this harness and installed it. See pics, I am 99.9% sure it is correct. That said, I am still blowing a fuse on high, tried 2 different switches.

edit- tested continuity on a 3 switches, 1 is bad, 2 are good. Unplugged headlights, brights on, pulled the switch, blew. So there is a positive issue somewhere.

 

[arcteryx]

Found the short thanks to the power probe. I hate electrical. It was the bright indicator rubbing in the cluster so I’ll be fixing that.