1974 low speed wiper not working

[cims1970fj40]

Need some help on figuring out why my wipers aren’t working on low speed. My wipers currently work on high speed and parks its self when pushing the knob back in the off position. I one point a few months ago it would come on for a second and blow a fuses but that’s not happening anymore. I had a local member a few years ago go through the motor and he verified that it worked in both speeds. After getting the motor back I replaced the connectors on it. I also had coolerman build another wiper harness for me and I believe he added the connector on the harness side.

Is it possible that if I had two of the four wires that attach to the connector on the motor side could be mixed up based on the current status? I have no electrical experience so would appreciate any insight. Thanks

 

[45Dougal]

First thing I'd do is pull the switch and give it a good clean out, along with the connector.
How's your cowl vent?
Water dripping onto your electrics?

 

[rkymtnflyfisher]

Check the connection up at the windshield, there are 2 wires that change color across the connector. Make sure they don't cross the connector color for color or you will have the problem you're having. @Coolerman has a write up on it on his website.

 

[cims1970fj40]

Thanks guys! Definitely not water damage. I haven’t had it on the road yet and it’s garaged.

 

[rkymtnflyfisher]

From Coolermans site.

Wiper Wiring Science

Toyota wiring mystery


While looking at the schematic and actual wiring, I became confused with the low speed wiring. I drew out the wiper switch, park switch, and motor connections on paper. I understood the Park function wiring and the high speed function wiring, but the low speed made no sense! If you go strictly by the wiring colors, and their positions on the wiper switch, park switch, and motor, the low speed would not work! Of course it does so what was up? Long story short, for whatever reason the connector on the windshield between the harness and the motor has the LB and the LW wires reversed in the connector! See Fig 7A above. Once I took that into account, everything fell in to place. On the drawings that follow I have drawn them as they actually are to keep it OEM... So don't email about the 'crossed' wires!

The following pics show what wires are involved to make the wipers work for EACH position of the wiper switch. I'll add the washer circuit later.

The red lines indicate where current is flowing so you can trace through the schematic easily. The wiper switch in each drawing has a gray box around the contacts that are active for that switch position. Finally the position of the Park switch is shown for each condition. Remember that the park switch is DOWN 90% of the time and is completely out of the circuit for the low and high switch positions.

 

[cims1970fj40]

From Coolermans site.

Wiper Wiring Science

Toyota wiring mystery


While looking at the schematic and actual wiring, I became confused with the low speed wiring. I drew out the wiper switch, park switch, and motor connections on paper. I understood the Park function wiring and the high speed function wiring, but the low speed made no sense! If you go strictly by the wiring colors, and their positions on the wiper switch, park switch, and motor, the low speed would not work! Of course it does so what was up? Long story short, for whatever reason the connector on the windshield between the harness and the motor has the LB and the LW wires reversed in the connector! See Fig 7A above. Once I took that into account, everything fell in to place. On the drawings that follow I have drawn them as they actually are to keep it OEM... So don't email about the 'crossed' wires!

The following pics show what wires are involved to make the wipers work for EACH position of the wiper switch. I'll add the washer circuit later.

The red lines indicate where current is flowing so you can trace through the schematic easily. The wiper switch in each drawing has a gray box around the contacts that are active for that switch position. Finally the position of the Park switch is shown for each condition. Remember that the park switch is DOWN 90% of the time and is completely out of the circuit for the low and high switch positions.

Thanks Ryan! Got it running on low now. It’s was the two wires that need crossing. Now I have to figure out what’s up with the turn signals and dash lights and gauge cluster lights as well. Other than that I think all the electrical components are good.