How do the tail lights ground?

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How do the tail lights ground?

jstone4646
I have nothing on the rear lights wise.  I found the plug along the frame and plugged it in but still nothing.  The bed was removed by the previous owner along with just about every ground wire on the whole truck so my guess is a ground wire is missing.  bulbs are brand new.
Project "Red" (not really named yet): '84 F150 4x2, Holley 4bbl 351 w/302 cam shaft and side exit pipes.  Still learning what else is there but in progress of putting her back together and on the road.
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Re: How do the tail lights ground?

grumpin
This is from my 1986 manual.

Dane
1986 F250HD SC XLT Lariat 4x4 460 C6-Sold
1992 Bronco XLT 4x4 351W E4OD
1998 GMC Sierra SLE K1500 350 4L60E
Arizona
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Re: How do the tail lights ground?

FuzzFace2
You did not say if style side or flare side so will post what I have seen on my 81's, 1 of each.
I would first start at the fuses. I would pull each one and test with a ohm meter.
If you check in place note not all fuses have power to them all the time. Some only have power when that system is turned on and the truck may need to be running or the key turned to run.

Once you know all the fuses are good and of the right amps you can find the 1 for running lights and with the truck running, lights on check that fuse if it has power in & out of it.
Now outside the truck on the inside frame rail where the floor & firewall meet the rear wiring harness plugs into the trucks main harness.
I would pull this apart to make sure it is in good shape then test for power to the rear lights. Remember the switch has to be pulled out (on) to get power at that plug.
You will have 1 wire that the power will be about 5-7 volts or if using a test light will blink. This is normal as it is the fuel gauge sender wire.

If you have a helper or jump out the brake light switch, Think 2 other wires will have power to them. This would be the left & right turn/brake light power wire.
You should also have another wire that would have power when the reverse lights are on.

So you should have wires in the plug for:
right turn/brake light
left turn/brake light
running lights
fuel sending unit(s) (if duel tanks you may have another wire that would blink when the other tank is switched to)
wire to the switching valve depending on year and motor
reverse light
and may have a ground

When at the back IIRC both of my 81 trucks had another harness for the rear lights that plugged into the frame rail harness.
I would check for power here before plugging in the light harness.
Should have:
right turn/brake light
left turn/brake light
running lights
and may have a ground

Now my flare side was a mess at this point so cant help much but from what I have found (could be wrong also) each light was grounded to the body. I can no longer get factory lights so I will do what is need when the time comes.

On the style side the lights had a ground wire that was screwed to the body behind the light. Some have said they don't have this and the lights ground thru the wiring harness.
Either way if you don't have power back there a ground will not make a difference.
Dave ----
Dave G.
81 F100 flare side 300 six / AA OD / NP435 / 2.75 gear
http://cars.grantskingdom1.com/index.php/1980-Ford-F100?page=1
81 F100 style side 300 six/SROD parts truck -RIP
http://cars.grantskingdom1.com/index.php/1981-Ford-F100
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Re: How do the tail lights ground?

85lebaront2
Administrator
In reply to this post by jstone4646
All of the rear end of the truck actually grounds inside the cab at G701 which is under the dash RH side near radio. It goes through two connectors to get there (this is from the 1986 EVTM which is on this site) C126 is the one at the LH rear of the frame and is single wire brown connector, the larger 4 pin is C1002 and provides the power to the lights C127 is underhood on the driver's side of the firewall. I swore years ago that the engineers who did the wiring on these trucks were on some serious hallucinogens when they designed it. If you can't find the mating piece for C126, you can try grounding that wire to the frame.

Good luck with it!
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413