Wiper differences

Silver Square · Jun 17, 2024

Anyone know what the difference is between the '73-77 and 78-87 wiper systems? I got a painless harness for my truck, and it shows them as being different. It comes pre-wired for the '78+, but provides instructions to add different connectors for the older trucks. Would it be advisable to put in the '78+ wiper motor when I re-wire the truck? Would I need to get the dash switch for a '78+ as well? Any other parts I'd need to do it?

Don-T · Jun 18, 2024

It takes a different wiper motor which means the linkage will have to be modified if I remember right. I made a new link to fit mine in. You will also have to get the later switch and if I remember right you will need a delay module that goes under the dash or make up a harness to bypass it, which is what I did. I had a hard time finding the connector for the later switch. I think I also had to modify my dash opening to fit the newer wiper switch. It was a much bigger job than I thought but I was not able to find a good wiper motor to fit my ‘73 and I needed it to pass state inspection.

If your wiper motor works well just change the Painless harness per their directions and save yourself a lot of trouble.

mattsk8 · Jun 19, 2024

I think it's odd that they split the differences between 77 and 78, because I think they didn't move the switch from the dash to the column until 1983 ish. Possibly this link might shed some light on this for you. I would also research which system worked the best and why it worked the best (this I don't know, they all have strengths and weaknesses). But unless you're building an original show truck, I would be leaning towards swapping it over to the 83 and newer system with the switch on the column. If you do go that route, finding an 84 or newer square in a junkyard to pillage wiper parts and harnesses will be HUGELY beneficial (you'll also need a steering column).

Deep Dive into GM Wiper Systems

Don-T · Jun 19, 2024

mattsk8 said:
I think it's odd that they split the differences between 77 and 78, because I think they didn't move the switch from the dash to the column until 1983 ish. Possibly this link might shed some light on this for you. I would also research which system worked the best and why it worked the best (this I don't know, they all have strengths and weaknesses). But unless you're building an original show truck, I would be leaning towards swapping it over to the 83 and newer system with the switch on the column. If you do go that route, finding an 84 or newer square in a junkyard to pillage wiper parts and harnesses will be HUGELY beneficial (you'll also need a steering column).

Deep Dive into GM Wiper Systems

My memory isn’t what it used to be but I think the changes started when they introduced the intermittent wiper module in about ‘78. They also had to change the way the park feature on the wiper motor works as well.

mattsk8 · Jun 19, 2024

Don-T said:
My memory isn’t what it used to be but I think the changes started when they introduced the intermittent wiper module in about ‘78. They also had to change the way the park feature on the wiper motor works as well.

That makes sense, I didn't know if they added delay to the dash switch or if they didn't add delay until they put the switch on the column. I had a 79 years ago but don't remember how its wipers worked.

dsteelejr · Jun 19, 2024

mattsk8 said:
That makes sense, I didn't know if they added delay to the dash switch or if they didn't add delay until they put the switch on the column. I had a 79 years ago but don't remember how its wipers worked.

I’m not 100% sure either, but what I can say for sure is my ‘80 K25 only has a two speed switch on the dash. I had an ‘84 K5 20+ years ago with the column switch and intermittent wiper speed, so I think 83ish for the changeover year is probably right.

bucket · Jun 19, 2024

The intermittent wiper option actually began in '77. The '78 and up wiper system is wired differently than the '73-'77 wiper system.

AuroraGirl · Jun 19, 2024

bucket said:
The intermittent wiper option actually began in '77. The '78 and up wiper system is wired differently than the '73-'77 wiper system.

also the wiper motor is 3 different options, early, middle, then 84-87 right?

bucket · Jun 20, 2024

AuroraGirl said:
also the wiper motor is 3 different options, early, middle, then 84-87 right?

I believe '85 was the changeover, but they still operate the same and can interchange. The newer ones don't have the built in washer pump, as it is remote and in the bottle. The remote pump can use the same two wires that went to the pump on the older wiper.

Don-T · Jun 21, 2024

bucket said:
I believe '85 was the changeover, but they still operate the same and can interchange. The newer ones don't have the built in washer pump, as it is remote and in the bottle. The remote pump can use the same two wires that went to the pump on the older wiper.

The wiring changed in '78 because the wiper motor park function changed from mechanical to electrical. My '73 had a mechanical park and built in washer pump. It now has an electric park function and built in washer pump. I have an '86 CUCV that has the same electric park and built in washer pump but I don't know if it is the same as the civilian version. The '73 has the dash switch and the '86 has the column switch.

bucket · Jun 21, 2024

Don-T said:
The wiring changed in '78 because the wiper motor park function changed from mechanical to electrical. My '73 had a mechanical park and built in washer pump. It now has an electric park function and built in washer pump. I have an '86 CUCV that has the same electric park and built in washer pump but I don't know if it is the same as the civilian version. The '73 has the dash switch and the '86 has the column switch.

Yes, the post of mine you quoted was referencing the two types of '78+ wiper motors. The dash switch went away in '84, but the wiper motor did not change at that point.

The '73-'77 dash switches do not jive with the '78+ wiper motor.

AuroraGirl · Jun 22, 2024

Don-T said:
The wiring changed in '78 because the wiper motor park function changed from mechanical to electrical. My '73 had a mechanical park and built in washer pump. It now has an electric park function and built in washer pump. I have an '86 CUCV that has the same electric park and built in washer pump but I don't know if it is the same as the civilian version. The '73 has the dash switch and the '86 has the column switch.

all cucv's are 1984 models i believe? So it makes sense you have the mid type washer setup

bucket · Jun 22, 2024

AuroraGirl said:
all cucv's are 1984 models i believe? So it makes sense you have the mid type washer setup

Good point, I always forget those CUCV's which were the exception to the rule in many many cases. You are right, all of them were based off of '84 model year parts.

AuroraGirl · Jun 23, 2024

bucket said:
Good point, I always forget those CUCV's which were the exception to the rule in many many cases. You are right, all of them were based off of '84 model year parts.

of course its a good point, i said it.

Jk, im not that self absorbed lol.

Wiper differences

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