Taillight Bulb
03-22-2018, 02:35 PM
#1
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Taillight Bulb
I’ve got an 87 pickup and trying to figure out what the small bulb in the bottom of the taillight housing that is circled is for. I’ve put new bulbs in on both sides and they don’t lite up. Not sure if I’m not turning the right thing on. Any help would be appreciated.
Last edited by bklf7; 03-22-2018 at 02:36 PM.
03-22-2018, 03:24 PM
#2
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That small bulb is a side marker light and is part of the tail light circuit. It is supposed to illuminate when the rest of the tail lights/parking lights are turned on (first click-stop).
It is really there to help illuminate the side of the lamp assembly for visibility and regulations. It eliminated the need for a separate rear side marker lamp found on the previous generation of trucks.
What bulbs are you using? Incandescent or LED?
My Owner's Manual says it is a 194 type bulb.
Check the bulb sockets as well as the connector for the tail light assembly for corrosion. Double check that both new bulbs are actually good.
It is really there to help illuminate the side of the lamp assembly for visibility and regulations. It eliminated the need for a separate rear side marker lamp found on the previous generation of trucks.
What bulbs are you using? Incandescent or LED?
My Owner's Manual says it is a 194 type bulb.
Check the bulb sockets as well as the connector for the tail light assembly for corrosion. Double check that both new bulbs are actually good.
03-23-2018, 06:25 AM
#6
If you get to the point of checking wiring, the tail light harness disconnects under the passenger side seat. You might need some extended leads to test the harness. From my experience, the end of the tail light harness is hacked up behind the tail lights in 4/5 trucks because someone tried to install some shotey trailer light kit made for a domestic and those kits almost always come with scotch locks. If your wiring is shot behind the tail lights, I make pig tails for them, if it's really bad I can make long pig tails, or the whole harness minus the cab connector (haven't source it yet).
03-23-2018, 07:03 AM
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I actually had that whole harness out and re wrapped it and didn’t see where anybody had a trailer wire harness installed. I’m going to test the socket first and go from there.
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03-24-2018, 02:15 AM
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Got them figured out. I had used some bulbs that were in my toolbox thinking they were new but noooope! Guess they were junk. Bought some brand new ones and what do you know they work. Thanks for the info to help me out.
03-24-2018, 01:57 PM
#9
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I am glad it was something simple like bad bulbs. 
I have seen a few people replace some expensive parts when the end the bulbs were bad. That's why I mentioned it.
I have seen a few people replace some expensive parts when the end the bulbs were bad. That's why I mentioned it.
03-24-2018, 01:58 PM
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