Headlights flicker
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Headlights flicker
Hi new to the site.
Just bought a 1994 7.3L turbo diesel. It is a 4x4 dually
The head lights flicker on and off after they have been on for a few minutes. This happens at all rpm and even when truck is off with lights on. There's massive amounts of wiring with covering to remove to look for bad wires and if it's covered it shouldnt be worn right? Also I see a 2 relay box next to the original power distribution box. Is this an add on modification? The lights work without either of these relay in place. I've check and cleaned a few grounds. No difference. Anybody have a simpler plan of action other that ripping out all the wire coverings.
Thanks
Just bought a 1994 7.3L turbo diesel. It is a 4x4 dually
The head lights flicker on and off after they have been on for a few minutes. This happens at all rpm and even when truck is off with lights on. There's massive amounts of wiring with covering to remove to look for bad wires and if it's covered it shouldnt be worn right? Also I see a 2 relay box next to the original power distribution box. Is this an add on modification? The lights work without either of these relay in place. I've check and cleaned a few grounds. No difference. Anybody have a simpler plan of action other that ripping out all the wire coverings.
Thanks
i ain't rite
Joined: Mar 2005
Posts: 65,565
Likes: 5,601
From: Marlboro Mental Hospital.
probably a bad switch and connector.
the headlight switch is rated for about the power the lights use, and if someone drove for a long time with the high beams on, it will overload the switch and start melting things.
remove the connector off the back of the switch and inspect closely. if there is any discoloration or melting at all, replace the switch and connector.
i added relays to my 88's headlights back in 1990 after the stock switch and connector burned up. the power now goes from the batteries through the relays to the light bulbs and the only thing the headlight switch powers is the low current side of the relay.
the headlight switch is rated for about the power the lights use, and if someone drove for a long time with the high beams on, it will overload the switch and start melting things.
remove the connector off the back of the switch and inspect closely. if there is any discoloration or melting at all, replace the switch and connector.
i added relays to my 88's headlights back in 1990 after the stock switch and connector burned up. the power now goes from the batteries through the relays to the light bulbs and the only thing the headlight switch powers is the low current side of the relay.
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I did some more grounds and got nothing. I guess its not pointless because I'm eliminating future problems... Maybe.. I plan on driving this thing hundred of thousands of more mile. It has 102k now. I just read about the switch and connector and I will check that out first chance I get. Do you have to pull the dash?
Laughing Gas
Joined: Mar 2016
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TJC is right on there is not sufficient load capacity in the stock wires and switch ..
also are the symptoms the same on high / lo beam ?
mine burned at the fuse block from hi beams .. i also installed a 30a relay .. near the battery and now run my highs through the relay .
also are the symptoms the same on high / lo beam ?
mine burned at the fuse block from hi beams .. i also installed a 30a relay .. near the battery and now run my highs through the relay .
Laughing Gas
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Ok thanks I'll be looking into it in the next couple days. How long do the replacement switches and wiring last? Prob not looking to do the upgrade with relays right now.
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i ain't rite
Joined: Mar 2005
Posts: 65,565
Likes: 5,601
From: Marlboro Mental Hospital.
if you do not use highbeams and do not add extra lights, you should have no problems getting 10 years out of a light switch.
mine burned up within 2 years because of the added lights for the snow plows.
mine burned up within 2 years because of the added lights for the snow plows.
Laughing Gas
Joined: Mar 2016
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"Prob not looking to do the upgrade with relays right now"
i put it off and put it off .. until one night my lights went out while driving ..
the lows still worked thankfully when i pushed the selector ..
it burned out my fuse block where the high fuse goes ..
i took the lead in and bypassed with an external fuse and then used that wire to then actuate the high beam relay ..
just saying .. i understand because i put it off too .. but all said and done it was an easy fix and i should have done it before something burned ..
lucky me it wasn't the switch or wires but it could have been ..
i put it off and put it off .. until one night my lights went out while driving ..
the lows still worked thankfully when i pushed the selector ..
it burned out my fuse block where the high fuse goes ..
i took the lead in and bypassed with an external fuse and then used that wire to then actuate the high beam relay ..
just saying .. i understand because i put it off too .. but all said and done it was an easy fix and i should have done it before something burned ..
lucky me it wasn't the switch or wires but it could have been ..
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Got it fixed
Ok had some time to play with it...
Took out gauge cover to get to headlight switch. Turns out he harness and switch were replace once already and I replaced them both again. Problem solved. However I will be going back in to do the relay upgrade. After seeing the switch had already been replaced once I decide I would do the upgrade for sure. Thank you so much for your help diagnosing the problem!!! I love this sight
Took out gauge cover to get to headlight switch. Turns out he harness and switch were replace once already and I replaced them both again. Problem solved. However I will be going back in to do the relay upgrade. After seeing the switch had already been replaced once I decide I would do the upgrade for sure. Thank you so much for your help diagnosing the problem!!! I love this sight
Lead Driver
Joined: Oct 2003
Posts: 8,476
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From: Madison, WI
If you really want to upgrade the dome/map light, get a housing from a '96 or later truck. They ditched that bigeffin' heavy metal thing that gets hotter than get-out with a stylish plastic one with "festoon" style bulbs. I did this with both our '95s, and put cheapo eBay LEDs in all of them, and it's a vast improvement. Just make sure to get a dimmable LED for the center dome light. Caveat - with the new style light housing, the tabs for the lens are VERY delicate, so be careful removing/installing it.
Haven't done anything with the door interior lights yet.
Haven't done anything with the door interior lights yet.
Cargo Master
Joined: Oct 2005
Posts: 2,298
Likes: 27
From: NJ
Just do relays, it's easy and worth the effort. These headlight switches and wire gauge is marginal for the load to begin with, add 30 years of age, wear, and PO hackjobs and you can have a problem. I suggest measuring voltage drop to the headlights to give you an indication of wiring condition. In any event, headlight relays (and Cibie housings with H4 bulbs) has been one of the best safety and comfort upgrades I've done to the truck. No idea how I drove several of these trucks around for so many years with junky wiring and headlights that were like holding a candle in the wind.
My upgrade thread: Fuse/Relay box install for headlight relays
My upgrade thread: Fuse/Relay box install for headlight relays
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