flickering headlights

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Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=26920
Printed Date: June 09, 2024 at 9:42 PM

Topic: flickering headlights

Posted By: carluv
Subject: flickering headlights
Date Posted: February 21, 2004 at 7:05 PM

i need some help on my '78 c-10 (full size gmc, 4 the uninformed). i am currently running a 4 lamp headlight system, 2-low, 2-high, configured to have all 4 lights on at same time (in low and high beam). this set up is from the '86/'87 year. all the wiring is good (no pinches/cuts/cracks/or grounding) but ive found that after aprox. 12 - 15 mins. the lights would start to "flicker" ramdomly. i installed a relay (potter & brumfield vf4-45f21) on the low beam wire, BUT now i have no high beams and i have the same problem occuring after aprox. 25 mins. now. i think i need 2 install a simmilar relay on the main power wire feeding the headlight switch, but i'm not sure how to do it exactly. all the wiring harness is in v.g. cond. (pulled from another trk/installed by myself) the dimmer (high/low) switch is new and this is not something that i'm new @, but i just can't figure it out-please help!

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noreplacement4displacement

Replies:

Posted By: daniel2002p
Date Posted: February 27, 2004 at 7:54 AM

make sure that the wire activating the relay is not crapping out on you.

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2005 Toyota Corolla S
1.8L VVT-i I-4
Always double check your wires with a DMM!!!
Do Not Use A Test Light!!!
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Posted By: carluv
Date Posted: February 28, 2004 at 1:33 PM

thanks for the input daniel2002p. the wires are fine- i've checked many times, with both a t.l. and a dmm. the problem i'm having is the lamps are causing a higher draw in amps, thus causing the switch to get warm and trip. NOTE: if i turn the lights off for a short time (5 - 20 secs.) it takes aprox. 5 mins. for it to happen again. soooo.... how do i install the relay inline for the main power supplyin' the switch? thanks for the input.

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noreplacement4displacement

Posted By: Toru
Date Posted: March 03, 2004 at 4:32 PM

Take the wire that runs from the switch to the lights and cut it. Hook the switch side to 85 and the headlight side to 87. If the headlight switch is switching ground, then connect 86 to +12V and 30 to ground, if the headlight switch is switching +12V, then hook 86 to ground and 30 to +12V.

Since you are adding a relay you may just want to get some weatherproof relays (one per side) and put them near the lights under the hood, and run +12V out from your electrical system (at alternator or main power distribution box) with a heavier (14-12) gauge wire. This should provide maximum voltage to your lights. More info here.

Choose a relay that can handle the current draw of the combined headlights (common auto relays are 30-40 Amps?)

Posted By: carluv
Date Posted: March 16, 2004 at 12:13 AM

thanks for the info toru, sorry i haven't responded sooner-been really busy.
this is what i've got runnin' on the light switch now.two relays wired in, one to the lows, one to the highs.the problem is when both relays are hooked up i get no lights at all!.but if i disconnect one of the other relays ( low or high) the other beam works.
the power for the relays are fed from the power supplying the dimmer switch (high/low switch), not from the main power feeding the on/off switch. i don't think this makes a difference, but i can't figure out exactlly why two relays wired in causes the light to shut off completely. i'm going to try wiring in weatherproof relays ( @ the lights) like you suggested- hopefully this solves everything,i'll keep ya posted.
anyone have any more input to this problem? thanks in advance.

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noreplacement4displacement

Posted By: carluv
Date Posted: March 27, 2004 at 3:11 PM

i see that there's been alot of interest (or is it just curiousity?) in this topic of mine, but i still can't seem to be able to solve the problem. i've installed relays,(weaterproof ones) at the headlights like toru suggested, and i thought "problem solved".

no such luck! the other night i was out for a few hours, and they started flickering again. now, i don't know what's goin' on, but this is getting to be a problem- people getting anoyed thinking i'm flashing my lights, cops askin' "what's the problem" and strongly advising me to get the problem fixed.

i've asked my friends who work at GM dealerships, these guys are long time techs, and they're just as baffled. does anybody have any ideas as to what else could be causing this?

thanks for any new input. posted_image

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noreplacement4displacement