JohnWad69

Need help 95 Z28 I lost my rear turn signal and break light on the driver side. I've replaced the turn signal switch, bulbs, sockets and wiring harness. I don't know where to go from here. Any help would be greatly appreciated. Thank you in advance

Injuneer

You need to include info about your car, year, model, etc.

You posted in what is basically the “audio” forum. I'll move this to “General 67-02 F-Body Tech” where you'll have a better chance of getting help.

JohnWad69

Thanks Admin. I'm new here and new to forums all together

ray42

John,

Chances are, you lost the Ground connection at the taillight fixture. Check inside the bulb sockets for corrosion, which is common on a 25+ year old car. Don't bother trying to fix a corroded bulb socket; that trick never works for very long. The auto parts stores will have direct replacement light sockets with wiring, for you. If needed, run a dedicated new Ground wire (from a solid chassis ground) to that taillight fixture, and if Ground goes to several places there, connect all of them to that new Ground connection. If that new Ground wire fixes the problem, you might want to apply a new Ground wire to the passenger's side fixture as well. No need to remove or trace any wiring, just add the new Ground wiring on top of the old Ground wiring. Keep us posted.

Injuneer

What "harness" did you replace? My initial thought was bad ground, but if only the driver side turn/brake lights are out, it narrows it down to a single wire. Each of the bulbs on both sides have a single wire that runs to splice S410 in the rear body harness, approximately 7cm for the left backup lamp breakout. From that splice a single wire runs to ground G400 bolted to the hatch release bracket.

Since you indicate you have already replaced the sockets and the harness, you need to test the continuity of the ground at each socket, to S410. If the ground is good, it's unlikely that the problem is on the12 volt side, since there is a separate 12V wire to each filament in each bulb. The 12 V comes from splice S400 in the body harness about 20cm from the P400 passthrough for branch through the left rear body panel.

If you don't already have a copy of the factory service manual, you can download a free copy here:

http://www.mediafire.com/?40mfgeoe4ctti

My info come from the 1994 version, you need to check vs. the 1995 version. See page 8A-110-4 for the schematic.

JohnWad69

I'm lost when it comes to looking at those electrical charts. I have a multi meter. I know how to use it. I dont know if it would effect the wiring to the rear lights or not but I had the carpet pulled out when I changed it a couple of days ago. I noticed that on the driver side floorboard under the carpet there was a black ground wire that's not hooked to anything. It is just conectted to the ground bolt and it's outside the wire loom and just laying there. I looked through the loom and didn't see a black wire where it could have broken off. I don't know if it is supposed to be hooked up or not but I figured I would let you know incase the turn signal/stop light has a ground through there. The free ground there appears to be factory wiring. Also I don't know if it has any significance or not but the car is a convertible

Injuneer

As I indicated above, the turn/brake lights ground to the rear hatch release bracket (one of 2 black wires with an eyelet). But ALL of the bulbs ground there - so if most of the bulbs are working, that ground is good.

The middle bulb on each side is both a taillight and a turn/stop light. Do all three bulbs on each side light up when the park or headlights are on? If so, that confirms the grounds are OK.

If the center light on the driver side does not light up at all it's most likely a ground problem.

JohnWad69

All are coming on with the exception of the center one on the driver side. I don't get it because it done the same thing with the other harness. That why I was asking about the other loose ground wire I seen. With everything else being replaced I figured it could have something to do with it. It would most likely have to be somewhere before the tail light harness wouldn't it? By the way thank you for your time and effort. I can't emphasize that enough. Please be patient with me I'm new at this. I just lucked out and fell into a car I've wanted most of my life.

Injuneer

The schematic clearly shows that ALL the rear bulb grounds go to the same ground point at the hatch hood down bracket. If you don't understand the schematics, you need to accept that. If the taillight filament in the center bulb lights up, the socket has a ground. If you don’t feel I know how to read the schematics let me know and I'll leave you alone. Perhaps a previous owner has modified the wiring. If that's the case, no way anyone who can’t physically examine the car can give you help. Or maybe you didn’t insert the bulb in the socket in the correct orientation.

If you still want my help, I'll tell you why you have to focus on the yellow wire the runs to the center bulb socket on the left side. It starts at the turn signal switch, see the line with the dark triangle outline with an “A” inside:

1995 4th Gen F-Body Exterior Lights

JohnWad69

Yes

JohnWad69

I just double checked the tail light is working on the driver side rear. It's just the blinker and the break light that's not

Injuneer

Again, just to be clear - Is the FILAMENT for the taillight lighting up in the center bulb on the driver side? If that is lighted up with the taillights on, the FILAMENT for the turn/BRAKE light is not getting 12 volt power when the turn signal is on or the BRAKE pedal is pressed.

If what is posted above is correct, pull the connector off the center bulb on the driver side, The connector has two wires - a brown wire for the taillight filament, and a yellow wire for the turn/brake filament. Set the meter to "DC Volts". Touch the red (+) lead of the multi-meter to the pin in the connector for the yellow wire. Touch the black (-/ground) lead to a good chassis ground (bright metal). Key on, turn on the left turn signal. See if the meter is pulsing, showing a positive voltage as the turn signal is supposed to flash. Alternatively, have someone step on the brake pedal to see a constant 12 volts.

If the meter sees 12 volts (or close to it) there is a problem with the socket or the bulb. Yes, I know they are both new, but it is easy to get a defective part with all the cheap Chinese crap on the market today, If there is no voltage showing up at the pin for the yellow wire, we have to start tracing the wire back to it's source.ar the turn/hazard switch assembly. There are two harness connectors in between.

JohnWad69

Going to check it now.

JohnWad69

I'm not getting any voltage from the yellow wire at all.
I went ahead and sanded the paint around the ground to make sure the ground wire had good connection.

Injuneer

Just to check things like the ground you selected, with the taillight on check the volts on the pin in the connector for the brown wire. If the filament was on when the taillights were on, there has to be 12 volts on the brown wire.

If the above check works out, there are two connectors for the yellow wire between the turn signal switch and the bulb harness connector. One is in the wiring harness behind the rear hatch area bulkhead sheet metal, under the carpet. The other is on the base of the steering column. I can give you the PIN numbers.