What does this wire do? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

willett · 10-31-2013, 04:03 PM

18ga Black wire with white stripe coming from back of wiper switch.

What's it for?

Thanks, spencer

mrolds88 · 10-31-2013, 05:58 PM

Correct me if I am wrong, but it should be classified as 150 in the wiring code which would be a ground.

ray_mcavoy · 10-31-2013, 07:42 PM

I noticed in your signature that you have a 78 with an 84 cab. What year wiring are you using?

The 78 diagram shows:

#150 = ground = solid black (no stripe)
#91 = low speed = black w/white stripe

In the low position, the wiper switch connects those two wires together, completing the ground circuit to run the motor at low speed.

The 84 diagram doesn't show any black wires with a white stripe. The ground #150 is still solid black and the low speed #91 was changed to gray.

Both years (78 and 84) show a black wire with a light blue stripe (#97). That one connects the wiper switch to the park switch that's inside the motor's gearbox.

willett · 11-01-2013, 01:03 PM

It's '78 wiring. Thanks guys.

willett · 11-01-2013, 01:05 PM

I just checked and I have no high speed. Must have something to do with that

10-31-2013, 05:58 PM	#2
mrolds88 Registered User Join Date: Jul 2011 Location: WV Posts: 946	Re: What does this wire do? Correct me if I am wrong, but it should be classified as 150 in the wiring code which would be a ground. __________________ 72 GMC C2500 402/Th400 first truck (still have) 77 GMC C3500 CC dually Sold 70 C50 dump truck "Rusty" 87 K10 Suburban Sold 93 K2500 xcab 6.5TD 96 GMC K2500 Suburban 6.5 TD

10-31-2013, 07:42 PM	#3
ray_mcavoy Registered User Join Date: Nov 2009 Location: Sherman, ME Posts: 2,373	Re: What does this wire do? I noticed in your signature that you have a 78 with an 84 cab. What year wiring are you using? The 78 diagram shows: #150 = ground = solid black (no stripe) #91 = low speed = black w/white stripe In the low position, the wiper switch connects those two wires together, completing the ground circuit to run the motor at low speed. The 84 diagram doesn't show any black wires with a white stripe. The ground #150 is still solid black and the low speed #91 was changed to gray. Both years (78 and 84) show a black wire with a light blue stripe (#97). That one connects the wiper switch to the park switch that's inside the motor's gearbox.

11-01-2013, 01:03 PM	#4
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	Re: What does this wire do? It's '78 wiring. Thanks guys. __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"

11-01-2013, 01:05 PM	#5
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	Re: What does this wire do? I just checked and I have no high speed. Must have something to do with that __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"

10-31-2013, 04:03 PM	#1
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	What does this wire do? 18ga Black wire with white stripe coming from back of wiper switch. What's it for? Thanks, spencer __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"



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