Rear Turn Signal Ground Wire (Location: Tail Lamp Bulb Socket?)
07-16-2010, 11:12 PM
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Rear Turn Signal Ground Wire (Location: Tail Lamp Bulb Socket?)
I have recently lost the right rear turn signal lamp. The system acts normal just like it does in any car when a turn signal bulb burns out (Dash Signal and front right lamp flashes fast). I checked the fuse (ok) and the bulb (ok). I also took a multi-meter and checked for voltage (none).
So I have established no voltage and am thinking that the ground wire has come loose or broke. I remembered when working on the right tail lamp on a different situation that there were two wires on the negative side of the bulb socket. Is the turn signal bulb grounded thru the tail lamp socket? If so could this be my problem. If not has anyone else experienced this issue.
FYI: I have yet to check with a multimeter to see if the positive bulb spring board is giving the bulb power or if the negative bulb socket has a loose or broken wire.
1986 928s
Blk/Blk
150,000+ mi
5spd
So I have established no voltage and am thinking that the ground wire has come loose or broke. I remembered when working on the right tail lamp on a different situation that there were two wires on the negative side of the bulb socket. Is the turn signal bulb grounded thru the tail lamp socket? If so could this be my problem. If not has anyone else experienced this issue.
FYI: I have yet to check with a multimeter to see if the positive bulb spring board is giving the bulb power or if the negative bulb socket has a loose or broken wire.
1986 928s
Blk/Blk
150,000+ mi
5spd
Last edited by Michael Robinson; 07-16-2010 at 11:13 PM. Reason: Make / Model / Year
07-17-2010, 12:07 AM
#2
Team Owner
some of the theory doesnt add up .
first there is only one positive and one ground per light.. so with this info remove the bulb turn on the parking lights and check for voltage at the center pin of the bulb socket.
next switch the DMM to continuity. ( beeps when the leads are touched)
check and see if there is continuity from the sidewall of the bulb socket to the chassis.
results you should have 12V at the center pin and there should be continuity to the chassis so please do this test and report back , this makes it easier to tell you how to repair.
a few quick things to do
make sure each socket on each light housing has the same bulb in it
IE a matched set side to side , different bulbs will throw off the bulb monitoring .
Also there is a ground point behind the right quarter panel abut 10 inches from the rear bulkhead, its bolted to the floor.
to get to it, its best to remove the hatch rear hold down braket 2 phillips screws then there are a few other screws along the bottom of the panel once they are removed you can bend the liner just enough without breaking it to reach the bolt with a wrench, use an eraser to clean the contacts,
Also use an eraser to clean all of the fuse ends as a dirty fuse can cause these issues
first there is only one positive and one ground per light.. so with this info remove the bulb turn on the parking lights and check for voltage at the center pin of the bulb socket.
next switch the DMM to continuity. ( beeps when the leads are touched)
check and see if there is continuity from the sidewall of the bulb socket to the chassis.
results you should have 12V at the center pin and there should be continuity to the chassis so please do this test and report back , this makes it easier to tell you how to repair.
a few quick things to do
make sure each socket on each light housing has the same bulb in it
IE a matched set side to side , different bulbs will throw off the bulb monitoring .
Also there is a ground point behind the right quarter panel abut 10 inches from the rear bulkhead, its bolted to the floor.
to get to it, its best to remove the hatch rear hold down braket 2 phillips screws then there are a few other screws along the bottom of the panel once they are removed you can bend the liner just enough without breaking it to reach the bolt with a wrench, use an eraser to clean the contacts,
Also use an eraser to clean all of the fuse ends as a dirty fuse can cause these issues
07-17-2010, 02:40 PM
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Well. I got it working. I was correct with my theory. The ground wire for the turn signal is attached to the ground bulb socket on the tail lamp. Two wires are soldered to the tail lamp bulb socket.
I checked this by taking the multimeter while the turn signal was on and found no voltage between the bulb pin and socket. I the checked the bulb pin with another ground and had voltage. Like I said I worked on the tail lamp a few days earlier an noticed two wires on the socket. I pulled the tail lamp bulb and found that one wire had broken off. I then soldered the wire back to the tail lamp bulb socket and the turn signal now works. It was quiet a job to solder inside that socket but I got it working. Nothing a pair of needle nose pliers and patience couldn't handle. Thanks for the advice.
I checked this by taking the multimeter while the turn signal was on and found no voltage between the bulb pin and socket. I the checked the bulb pin with another ground and had voltage. Like I said I worked on the tail lamp a few days earlier an noticed two wires on the socket. I pulled the tail lamp bulb and found that one wire had broken off. I then soldered the wire back to the tail lamp bulb socket and the turn signal now works. It was quiet a job to solder inside that socket but I got it working. Nothing a pair of needle nose pliers and patience couldn't handle. Thanks for the advice.
