Tail lights Not Working
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Tail lights Not Working
Greetings
I have a 1977 F150 with some of the tail lights not working. This is the two-wire socket. The three-wire socket - brake lights, turn signals, work. And the back up lights don't work. So..... how to trouble shoot?
EDITED: The two-wire sockets on both sides of the truck do not operate. The three-wire sockets do operate on both sides of the truck. The back up lights do not work on either side.
I have a 1977 F150 with some of the tail lights not working. This is the two-wire socket. The three-wire socket - brake lights, turn signals, work. And the back up lights don't work. So..... how to trouble shoot?
EDITED: The two-wire sockets on both sides of the truck do not operate. The three-wire sockets do operate on both sides of the truck. The back up lights do not work on either side.
Last edited by Crowell; Sep 5, 2021 at 08:49 AM.
Tuned
Joined: May 2006
Posts: 304
Likes: 77
From: St Paul MN
These kind folks have the wiring diagrams here:
https://www.fordification.net/tech/wiring.htm
I have a heck of a time reading them, but basically you look until you find your end use (reverse light) and then follow the diagram back up.
i usually check to see if I have voltage with a voltmeter or multimeter at the fuse panel, then check the bulb then go backwards to the wire harness, etc until you figure out where it is.
Frustrating fun as they say.
Is it just your reverse lights or is it your running lights too?
Running lights, brakes, blinkers (hazards) are all on the three wire connection. Reverse is just reverse.
https://www.fordification.net/tech/wiring.htm
I have a heck of a time reading them, but basically you look until you find your end use (reverse light) and then follow the diagram back up.
i usually check to see if I have voltage with a voltmeter or multimeter at the fuse panel, then check the bulb then go backwards to the wire harness, etc until you figure out where it is.
Frustrating fun as they say.
Is it just your reverse lights or is it your running lights too?
Running lights, brakes, blinkers (hazards) are all on the three wire connection. Reverse is just reverse.
FTE Legend
Joined: Nov 2015
Posts: 30,860
Likes: 4,106
From: Angier, NC
As said check / replace the bulbs & the fuse.
If they are good / new (may not be good even new) check the reverse switch to see if you have power at it.
If so jump it so power goes to the lights and see if they work.
If so you know the switch is bad.
BTW you did not say what transmission you have so can help where the switch would be.
Dave ----
If they are good / new (may not be good even new) check the reverse switch to see if you have power at it.
If so jump it so power goes to the lights and see if they work.
If so you know the switch is bad.
BTW you did not say what transmission you have so can help where the switch would be.
Dave ----
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It doesn't have running lights, so it's reverse lights only.
And the tranmission is a standard manual transmission on the steering column. 3 on the tree.
And the tranmission is a standard manual transmission on the steering column. 3 on the tree.
Last edited by Crowell; Sep 5, 2021 at 03:34 PM.
Fleet Mechanic
Joined: Sep 2014
Posts: 1,626
Likes: 78
From: NE Texas
Separate your problems... one is that your backups don't work, one is that some of your running lights do not work.
You only have three options: juice to the sockets and bad bulbs, juice to the sockets and bulbs but bad grounds, or no juice to the sockets.
Using a test light or a multimeter, check if you actually have juice to the sockets. (You probably do for the running lights if the three-wire sockets next to them do.)
Check that you actually have continuity between the socket's shell/ground and the end of the ground wires. Clean your grounds.
Test the bulbs to be sure they work.
If you don't have juice to the sockets use the wiring diagram to find out where you are losing the juice.
You only have three options: juice to the sockets and bad bulbs, juice to the sockets and bulbs but bad grounds, or no juice to the sockets.
Using a test light or a multimeter, check if you actually have juice to the sockets. (You probably do for the running lights if the three-wire sockets next to them do.)
Check that you actually have continuity between the socket's shell/ground and the end of the ground wires. Clean your grounds.
Test the bulbs to be sure they work.
If you don't have juice to the sockets use the wiring diagram to find out where you are losing the juice.
Lead Driver
Joined: Mar 2004
Posts: 8,922
Likes: 152
Greetings
I have a 1977 F150 with some of the tail lights not working. This is the two-wire socket. The three-wire socket - brake lights, turn signals, work. And the back up lights don't work. So..... how to trouble shoot?
EDITED: The two-wire sockets on both sides of the truck do not operate. The three-wire sockets do operate on both sides of the truck. The back up lights do not work on either side.
I have a 1977 F150 with some of the tail lights not working. This is the two-wire socket. The three-wire socket - brake lights, turn signals, work. And the back up lights don't work. So..... how to trouble shoot?
EDITED: The two-wire sockets on both sides of the truck do not operate. The three-wire sockets do operate on both sides of the truck. The back up lights do not work on either side.
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Lumpy78
1973 - 1979 F-100 & Larger F-Series Trucks
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Jun 19, 2009 04:18 PM
