Help: Driver tail light intermittent

[Zealous]

Hey,

I have been having an intermittent problem and not sure how to fix and wanted to get some input from you guys to see if there is an easy fix? I have an intermittent rear tail light on the drivers side. Basically I changed out all the bulbs and made sure I had the correct 1157s where required. I then checked the wires and looked good to me except looks like previous owner spliced some of the wires together as I know the car was rewired at some point in the past. Both rear brake lights were then working. Recently the problem came back and the drivers side cut out (but it might have been occurring the whole time as I can not see the tail lights) and then later was working again. Even got pulled over by the bored Mountain View Police and was told the drivers brake light cut out at one traffic light and then came back on at the next. I looked last night leaving from GFs place and could not get the driver brake light to come back. Decided to drive as is and check again when I got home, low and behold it was working again.

I am thinking it might be a bad ground. Tonight I plan on cleaning the bulb sockets and making sure the spliced wires are clean and have good contacts. Other than that I have no idea. I need to do my CA licence test tomorrow and would rather not fail it because that 15 mins is the random off as opposed to the random on. I know should have posted earlier

How do I go about diagonising this problem and fixing it tonight so I do not have to be wondering if 1 brake is cutting in and out? Whats the best way to check the grounds? I am a novice to car electrical so am really just fiddling and hoping at this point and really could use some help.

Any advice, tips or help would be greatly appreciated.

As reference, I have a 1971 240z originally a series 1 but had the dash and engine replaced from a 1972. Let me know if you need any more information. I will try to take photos when I get home today.

[240ZX]

I see that you have a 1971 Z. When I encountered similar issues on my 1970, I finally decided to replace the complete turn signal/switch assembly on the steering column....all my intermitent electrical issue went away! Just a thought to ponder. These old switch assemblies do wear out!

Tom

[Zs-ondabrain]

I second that. It was the first thing that popped in my head. Try this...

Wiggle the turn signal shaft up and down while using a large mirror or second person to watch the taillights. If they blink or come on and off due to the wiggling, the problem is obviously in the switch and you need to take it apart and clean it, Plenty of articles and threads on the subject on this site.

If the problem is not there, Try wiggling the Hazard switch. Everything runs thru that switch (turn signals and brakes) and if it's damaged or wearing out, there lies your problem. If the results show the problem is in the switch, remove it and see if you can clean the contacts inside.

Grounds are the worst part of a Z's systems. Double check your connections, grounds and such. Good luck.

Dave.

[Zealous]

Just want to check that I explained appropriately, as I think I confused tail light and brake light in the original post:

* The indicators work fine

* The driving tail lights work fine

* But the drivers side BRAKE light is intermittent

Would the problems with the switch you mention still pertain to the driver side only brake light cutting in and out? I would find it weird that it would be at the light/ combo switch if the passenger side brake light works fine but the drivers is intermittent. This is why I am thinking the wiring and grounding might be at fault...

But again I am at a loss after trying a few times in the past and thinking I fixed the problem only to have a buddy at a later date say drivers brake light is out.

*******Warning Stupid Electrical Question***************

How do I go about checking the grounds in the rear area?

[Zs-ondabrain]

In your Z, the brake lights and turn signals in the rear are the same thing. They both use the same wire that goes thru the Hazard andturn signal switch.

When you make a left turn, the switch disconnects the brake wire and reroutes it thru the Turn signal flasher, making the left brake light flash. The brake wire runs from the barke pedal switch to the turn signal, then the switch splits the signal and sends it to the Hazard switch and back out to the left and right taillight.

This is what I do for a living. Your first post was explained well and I understood it. Check the T/S switch as well as the hazard switch. Most people forget or don't know that the brakes and turn signals are the same thing and run thru the T/S and hazard switches. ANd now you know. Wasn't that fun.

To check the grounds in the rear, Just use and OHM's meter and connect it to a good shiny metal area and the other test lead to the black wire on the rear harness. You should have a very low reading, like 0 ohms is the best. anything above that and you should start cleaning connectors and maybe even tap the black wire and ground it back there, to a good spot. Use a dremmel to clean a spot of metal, then use a self tapping screw or use a stock bolt to secure the new wire.

Edited January 26, 2009 by Zs-ondabrain

[Zealous]

Thanks Dave much appreciated Ill give it a go when I get home. This year I want to fix all these niggling problems for piece of mind. Ill keep you updated and I might need your services again for combo T/S switch

[Zealous]

Thanks Dave, I found out it is in T/S switch that has always been a little loose and flakey so if the brake light goes out all I have to do is put the indicator on for a quick blip and its back. Any ideas how I can do a quick fix for tomorrow? I used dust off so far to clean contacts of dust but I guess the corrosion and other problems are still there. It will have to wait to strip down and clean till I have more time.

For others who come across my problem in the forum search here are some good links for information and solutions:

Rebuilding Combination Switch

http://www.classiczcars.com/forums/showthread.php?t=17688

Combination Switch rebuild

http://www.classiczcars.com/forums/showthread.php?t=23325

Other rebuild and repair

http://www.classiczcars.com/forums/showthread.php?t=23266

I could do this but since mine need a rebuild I think I will go with another one of Dave's magnificent solutions.

http://www.classiczcars.com/forums/showthread.php?t=24304

Dave thank you so much and PM sent

[srbigbutt]

I'm having a similar issue with one of my tail lights, but I think its because the bulb is not making good contact in the housing. The spring is worn out and doesn't make contact with the bottom of the bulb. I have fixed it a couple times but I probably just need to replace it.

[Zealous]

srbigbutt,

Thanks for the tip, it was one of the first things I checked but always best to start with easy stuff before tearing things apart. Part of the reason I posted was to find if it was a simple thing I had missed before I started chasing every single wire down.

A good scotch bright will clean up corrosion and then just fix the spring and you should get good contacts. However, your problem should only be for a single bulb and so the other should compensate. I know I have read that people recommend di-electric grease to prevent further corrosion.

My problem is the all the brake bulbs on the drivers side are intermittent. That is what led me to a ground problem, but thanks to Dave and 240ZX I have found out it is definitely the T/S switch. T/S always felt loose and ticker occasionally did not sound so maybe Ill kill two birds with 1 stone. I just need to find time to take it out and have a look and send to Dave for TLC.

[Zealous]

Just to close out the thread. Problem solved. Dave does really amazing high quality work!!!! The T/S and combination switches look so good, are tight and work perfectly! Only problem is they look better than the steering column cover now

I guess the next thing to get from Dave is the LED upgrade

Looks like someone wrongly replaced the 3 wire bulb socket with a 2 wire on my drivers side. Does anyone know where you can buy new bulb sockets that can be wired into the rear harness?

[Zs-ondabrain]

I've got lots of extra harness for the taillights. If you still need a 3 wire socket, I'm sure I could find one for you with ease.

Thanks for the compliments, I try to do Every switch as if it were going to be installed into my own Z. Glad you like 'em.

Dave.