The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 7-pin versus 8-pin headlight switch

Resto-Rat · 07-12-2018, 05:42 PM

Well, I replaced the NEW switch with a second NEWEST switch and works like a charm. The first NEW switch tested with both power and continuity and resistance, so I really don't think the switch was bad, unless as you point out there is some form of circuit breaker or there is an internal wiring configuration that somehow puts a ground in the circuit.

The 8-Pin part number for NAPA ProFormer is HL6554SB Switch / Commutateur Interruptor and oddly enough it is $5 bucks cheaper.

The 7-Pin part number for NAPA ProFormer is HL6613SB. This was not the correct switch for my 1970 GMC Jimmy.

I actually believe it is just important to get the correct switch for your year model and harness configuration and I am under the impression, unverified, that the switch over (no pun intended) was around 1970. Only way to tell is to look on your existing switch and see if there is a spade in the number 7 position indicated on the switch, and if there is then it is an 8-pin switch. If NO Spade, then it is a 7-pin switch.

Now my wiring connector did not have a wire from the harness into that #7 spade nor did it have one in the #3 position, but that possibly is of no consequence.

Hope this helps anyone having this issue down the road.

Thanks ZoSopp for the input.

Attaching picture of my old switch with the 8 pins along with a diagram from American Autowire labeling the spade functions.

https://www.americanautowire.com/vie...uit-functions/ (Not advertising and I have not actually bought anything from them, but they posted this diagram and it was helpful to me - so figure i needed to give credit.)

Sammy

07-12-2018, 05:42 PM	#3
Resto-Rat Registered User Join Date: Jun 2018 Location: La Grange, Texas Posts: 11	Re: 7-pin versus 8-pin headlight switch - 1970 Jimmy Well, I replaced the NEW switch with a second NEWEST switch and works like a charm. The first NEW switch tested with both power and continuity and resistance, so I really don't think the switch was bad, unless as you point out there is some form of circuit breaker or there is an internal wiring configuration that somehow puts a ground in the circuit. The 8-Pin part number for NAPA ProFormer is HL6554SB Switch / Commutateur Interruptor and oddly enough it is $5 bucks cheaper. The 7-Pin part number for NAPA ProFormer is HL6613SB. This was not the correct switch for my 1970 GMC Jimmy. I actually believe it is just important to get the correct switch for your year model and harness configuration and I am under the impression, unverified, that the switch over (no pun intended) was around 1970. Only way to tell is to look on your existing switch and see if there is a spade in the number 7 position indicated on the switch, and if there is then it is an 8-pin switch. If NO Spade, then it is a 7-pin switch. Now my wiring connector did not have a wire from the harness into that #7 spade nor did it have one in the #3 position, but that possibly is of no consequence. Hope this helps anyone having this issue down the road. Thanks ZoSopp for the input. Attaching picture of my old switch with the 8 pins along with a diagram from American Autowire labeling the spade functions. https://www.americanautowire.com/vie...uit-functions/ (Not advertising and I have not actually bought anything from them, but they posted this diagram and it was helpful to me - so figure i needed to give credit.) Sammy Attached Images