1978 k20 wiring nightmare - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Adamcalnan · 04-10-2016, 01:38 AM

I have a 1978 Chevy k20. The wiring on my truck has been a nightmare. Now I have replaced the 2 relays under the dash and searched for hours. When. I turn either sides turn signals on all of my lights blink on the outside of the truck minus my headlights, including my cab lights. Any help would be greatly appreciated!

nsstring · 04-10-2016, 07:32 AM

Start by pulling all the turn signal bulbs and see if one of them is a single contact bulb. If so it connects across the park/tail light and will make them all blink.

**hatzie** · 04-10-2016, 11:18 AM

Grounds... Look at the radiator support grounds first.
Just because the black wire jacket looks good doesn't mean there's still copper inside the jacket...

Pontiac1976 · 04-10-2016, 11:42 AM

Quote:

Grounds... Look at the radiator support grounds first.
Just because the black wire jacket looks good doesn't mean there's still copper inside the jacket...
__________________

"GROUNDS" Very true. Bad grounds will do all kind a stuff. They have you casing all kind a stuff. All start with the easy stuff go throw A-Z

04-10-2016, 01:38 AM	#1
Adamcalnan Registered User Join Date: Apr 2016 Location: statesville Posts: 1	1978 k20 wiring nightmare I have a 1978 Chevy k20. The wiring on my truck has been a nightmare. Now I have replaced the 2 relays under the dash and searched for hours. When. I turn either sides turn signals on all of my lights blink on the outside of the truck minus my headlights, including my cab lights. Any help would be greatly appreciated!

04-10-2016, 07:32 AM	#2
nsstring Registered User Join Date: Feb 2016 Location: West Palm Beach, FL Posts: 4	Re: 1978 k20 wiring nightmare Start by pulling all the turn signal bulbs and see if one of them is a single contact bulb. If so it connects across the park/tail light and will make them all blink.

04-10-2016, 11:18 AM	#3
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,941	Re: 1978 k20 wiring nightmare Grounds... Look at the radiator support grounds first. Just because the black wire jacket looks good doesn't mean there's still copper inside the jacket... __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.



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