Author Topic: Weird headlight problems......  (Read 501 times)

Offline shinkle

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Weird headlight problems......
« on: December 30, 2021, 06:32:32 PM »
I have original 87 R10 with 4 headlight set up. Running lights/turn signals in the grille and running lights/turn signal on the outter front panels. The 2 upper lights are the dim and the 2 lower lights are high beams. All 4 are on when high beams are selected but only the top 2 when dim is selected. My issue:

Randomly my passenger turn signal arrow on the dash will glow greeen. When I turn the signal on it blinks really slow. Bigger problem is the passenger upper dim headlight goes out. Then out of nowwhere the driver side upper will go out. Occassionaly no dim lights at all. If I turn on high beams all 4 lights work great. I never have any issue with the lower 2 high beam lights, turn signals in the grille or on the outter front panels. Only intermittent on off upper dim lights and the weird arrow glow slow blinker.
1987 R10 5.7L TBI

Offline JohnnyPopper

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Re: Weird headlight problems......
« Reply #1 on: December 30, 2021, 08:26:47 PM »
Don't know exactly, but from what I have seen in this forum: Look for grounding problems i.e. make sure your grounding cables (many) are in good shape  8)
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline shinkle

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Re: Weird headlight problems......
« Reply #2 on: December 31, 2021, 01:28:33 PM »
Thanks all. I cleaned all the grounds and it seems to be working ok. Also discovered the plastic protective housing on the passenger low beam wires was broken. The brown wire and green wire would slightly push out of the clip when I tried connecting the wires to the bulb.
1987 R10 5.7L TBI

Offline juancano

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Re: Weird headlight problems......
« Reply #3 on: January 03, 2022, 11:46:00 AM »
I bought an 86 c10 and was having all kinds of blinker and headlight issues. Turned out the steering column wiring was fried, literally. Had to replace all that. Also, don't use LED bulbs for turn signals or for the dashboard, makes the turn signals act up.

Offline Mr Diesel

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Re: Weird headlight problems......
« Reply #4 on: January 03, 2022, 02:23:35 PM »
A lot of strange dashboard light problems can be traced to one or more bulbs being burned out, causing ground issues or weird electrical imbalances. Check every single bulb on the exterior of the truck. Replace any burned out (headlights, turn signal bulbs, running lights) and reassess the issue.
1976 C20 Crewcab, 6.2L/SM465
1982 K30 Crewcab , 427TD/TH400
1983 C30, 6.2L/TH400
1983 K30 Crewcab 454/700R4
1986 K10 350/400. 1989 K30 cab/chassis 454/SM465