GMC headlight upgrade issues
 

I originally posted this in ELECTRICAL but got no response so I'll try it here.

I recently upgraded the headlights on my 68 GMC with the Hella 002850811 kit (https://www.amazon.com/HELLA-0028508.../dp/B001G7A9YS). I only changed the outside two lights and I did not upgrade the wiring or add relays, though I plan to someday. The improvement over the old lights is very noticeable but I have one issue. When driving with the brights on the lights will intermittently go off for a split second. It varies from a flicker to going completely dark for a full "Mississippi." It never did this with the old lights and it still doesn't do it when on dim. Last night I made a test drive and kept one eye in my side mirror to see if the side markers flickered when the lights did but they did not. It's not a daily driver so I'm not going to drive it at night until I get this fixed. Any suggestions will be greatly appreciated.

Jeff

Re: GMC headlight upgrade issues
 

I don't know what the load is but the headlights are driven through an auto-reset breaker that I bet you're tripping. You need a proper relay in there.

Re: GMC headlight upgrade issues
 

^^^^^What he said^^^^^

Those headlights pull more amps than standard ones, overloading the circuit.

Install a proper headlight harness with the relays. This will power the headlights right off of the battery, not through the headlight switch.

Re: GMC headlight upgrade issues
 

10-4. I've got the relays on order. Thanks for the advice.

Let me know your final setup as I want to copy it!!!!
Thx
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Re: GMC headlight upgrade issues
 

What wattage H4 bulbs did you use? Standard H4s are 55/60W and can go much higher. I believe the stock were closer to 35W. The higher wattage would trip the breaker.

Re: GMC headlight upgrade issues
 

So there were auto-reset breakers in 68 in the headlight circuits of GMC?

Re: GMC headlight upgrade issues
 

Jegs website says those are standard H4 12V 60/55W Bulbs.

OP, you might consider upgrading the inner (high beam only) lamps to E-codes also. These Hellas use H1 bulbs and being dedicated high-beams, should easily outperform your H4s, which have to perform the separate duties of low beam and high beam. http://www.rallylights.com/h5001-hel...dlamp-kit.html


Google might find others (I didn't look). I would stick with an established European brand with proven quality, such as Hella or Cibie.

Re: GMC headlight upgrade issues
 

This is what I have on order: https://www.classicindustries.com/product/mx01133.html

Re: GMC headlight upgrade issues
 

The first harness that came in was incorrect. Even though the packaging said "4 headlights" it was actually for a 2 headlight set up. Classic Industries promptly sent the correct one and I spent a little time the last couple nights installing it. It did indeed take care of the problem. I drove about 5 or 6 miles last night and did not see even a flicker. Now I just need to spend a little time getting the lights aimed a little better and all will be good in the headlight department. Thanks for all the help.

Re: GMC headlight upgrade issues