Rear Window wiring question (2 Viewers)

[NikP]

The previous owner obliterated the rear window wiring and now that I'm putting things back together I'm curious about a few things.

I'm missing the relay in the wiring harness. What's its purpose? It looks like it's isolates the two switches in the circuit. Is that it?

Is there anything that limits travel of the window? Without knowing if the relay had other functions, what stops travel at the top or the bottom? Does the relay or circuit breaker in the stock circuit do anything to stop the motor?

Does anyone have a more detailed wiring which might include the relay internal wiring? I'm trying to figure out function and what I might need to purchase to make things work.

 

[NikP]

Okay if nobody has wiring insights, tell me how it works.

Do you have to turn the switch off at the bottom or the top? What happens if you keep the switch on when it gets to the top? Or the bottom? Will the circuit breaker kick in and turn off power before the motor breaks the plastic gear (Assuming you still have one).

 

[J Mack]

Do you plan to use the factory switch on the dash?
Do you plan to use the factory safety switch on the rear tailgate?

 

[NikP]

I have the wires in place that go from the dash switch to the tailgate. I can activate the tailgate window to go up and down but I haven't yet installed the glass. I haven't got a key for the tailgate key switch so it's not installed. I'm contemplating just wiring a 2 pole switch somewhere near the rear until I get keys.

From the stock wiring diagram, it shows a relay after the circuit breaker. I don't have a relay so I'm curious if it matters. Electrically I cannot tell why it's even in the diagram. Since I've never had a working window, I'm just curious if the circuit breaker will kick in to protect all the gears and glass. I don't want to test it and break something.

I have the wiring and safety switch all figure out, it more about the operation. I'm guessing the circuit breaker, or relay remove power if it gets bounced up or reaches the top or bottom of travel. Which one? If it's the circuit breaker, I'm good. I just can't figure out what the relay was supposed to do.

 

[J Mack]

Early doesn't use relays

Late does

 

[PabloCruise]

Gary's write up shows a relay:

 

[J Mack]

Just hook it up like the early style in my top photo.

If you don't plan to use the tailgate safety switch then just ground 3WB at the motor, if you are going to use the safety switch then it breaks the ground when the tailgate is down and makes when the gate is up.

The dash switch and keyed tailgate switch are connected in a parallel configuration.

 

[J Mack]

I have the wiring and safety switch all figure out, it more about the operation. I'm guessing the circuit breaker, or relay remove power if it gets bounced up or reaches the top or bottom of travel. Which one? If it's the circuit breaker, I'm good. I just can't figure out what the relay was supposed to do.

Sorry I was taking pictures and typing a reply when you posted this and missed it.

The motor is low toque and will stall before you brake the glass or damage anything else, obviously some common sense will help too but to answer your question, no you don’t need a relay, a 30 AMP blade fuse will work fine if you use common sense and don’t hold the window switch in the up or down position for an extended time after the window has completed the desired action. If you’re going to let the young kids operate the window then a resettable fuse wouldn’t be a bad idea, (personally I don’t like them)

 

[NikP]

The motor is low toque and will stall before you brake the glass or damage anything else....

Thats what I needed to know. I also didn't know there were two wiring diagrams so I guess I'm not missing anything.

Thanks @J Mack

 

[PabloCruise]

Early doesn't use relays
View attachment 2246262

Late does
View attachment 2246263

Anyone know the cut-off from Early to Late?

 

[WarDamnEagle]

Anyone know the cut-off from Early to Late?

According to ToyoDIY it was early 1970:

85915-20021	FOR TAIL GATE (09/1977 - 06/1980)	1	$127.43
85950-30011	FOR TAIL GATE (03/1970 - 08/1977)	1	$120.94

 

[PabloCruise]

According to ToyoDIY it was early 1970:

85915-20021	FOR TAIL GATE (09/1977 - 06/1980)	1	$127.43
85950-30011	FOR TAIL GATE (03/1970 - 08/1977)	1	$120.94

They went to the relay pretty quickly then!

 

[J Mack]

Anyone know the cut-off from Early to Late?

According to my Haynes book it was pre 1972.
Gary's write up shows the relay interrupting both switches but doesn’t show where it get signal.

Haynes shows the relay interrupting only one of the switches and getting signal from “tailgate remote control switch”

Either way if you wire like an early (no relay) your tailgate window will operate.

 

[bobm]

There's a Reason

 

[J Mack]

There's a Reason

Taking a wild a$$ guess the relay is tied to the interior switch and because it's powered by the turn signal fuse it will disable the interior window switch when the ignition switch is off.
Not sure why that would be desirable but that's the only logical reason to have that relay circuit.

 

[bobm]

There's a Reason

 

[Ol Yeller]

There's a Reason

I’m thinking Bob is enjoying shelter in place quite a bit

 

[scrapdaddy]

Put down the Bud, Bob.

 

[bobm]

Only been 5 years

 

[PabloCruise]

There's a Reason

Right, like not wanting to drive that current through the switch. Crispy contacts...