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View Full Version : Rear Taillights: Center Running Light Flashes On Both Sides With Amber Turn Signal



kings1527
09-24-2013, 12:40 PM
Here's a new one that just started after I put my engine back together from doing some completely unrelated work to this. When I use my turn signal, my center running light in the middle of the rear marker will flash in conjunction with my turn signal. The running light will flash on BOTH sides. For example:

-I signal for left hand turn.
-My left rear amber flashes
-My left rear running light flashes with my left rear amber
-My right rear running light flashes with my left rear amber and left rear running light.

I have some PJ Grady upgraded boards on their way but I'm not sure if that's entirely the issue. I have converted to LEDs but I haven't had this problem. It just started all by itself, quite possibly after a car wash but I'm not sure if this was going on before or only after the wash.

I've swapped the boards around and no matter which side, they do the same thing.

Any thoughts? Grounding issue?

Thanks!

Greasy DeLorean Mechanic
09-24-2013, 03:02 PM
Does your car have the 4 way (side marker) turn signal mod? If so, make sure splices are on the correct wires (ignore Green/Purple and Red/Orange/Black crossover at my tail light board connectors -- that's a different mod):

688

Side markers and running lights are tied together.

Bill Robertson
#5939

Greasy DeLorean Mechanic
09-24-2013, 03:16 PM
Use an ice pick light (bulb in handle test light) to isolate the problem before/after the bulkhead connectors:

All rear lights are routed through the Black bulkhead connector. Turn signals are left side 3rd from bottom (right turn signal) and right side bottom most (left turn signal). Running lights are left side 2nd from bottom (left running light) and left side bottom most (right running light).

Dave Delman did a real nice graphic layout of the bulkhead connectors, but I unfortunately don't have a copy in the cloud (I'm traveling at the moment). If someone hasn't posted it by the time I get home I'll upload a copy.

Bill Robertson
#5939

kings1527
09-24-2013, 04:00 PM
Excellent. Thanks for the info, Bill. If you get a chance to put up Delman's layout, I'd appreciate that.

I'm at work and I'm not sure if we have an ice pick here but I'll look and let you know what I find. And no, I don't have the mod for the flashing side markers. Everything was fine before I started doing my engine work (i.e. water pump, powdercoat valve covers, new coolant lines, etc). All unrelated stuff.

I have some Grady boards on the way so I'll see if that helps but this problem seems unrelated to circuit board issues.

If anyone else has any thoughts, please let me know.

kings1527
09-24-2013, 04:04 PM
Nevermind on the Delman diagram, I found it. Thanks!

kings1527
09-24-2013, 05:43 PM
I stand WAY corrected. Apparently, my car DOES have the flashing side marker mod and I seriously never noticed it before. I haven't done any messing with that wiring since I got the car but I find it interesting that I just noticed it, along with the lights not functioning right. Anyways, now I just need to locate where the PO made the mod and see what's going on.

Is there a common location?

I wouldn't mind restoring it back to its regular configuration if it improves reliability. I hate having these issues. I don't have a working ice pick here at work so I'll have to wait until I get home tomorrow to really isolate the problem. But I think it's safe to say that since I have the flashing side markers, this is a good place to start as far as figuring the problem out.

Greasy DeLorean Mechanic
09-24-2013, 05:53 PM
Front splices are typically made either behind the grille or headlights, rear splices behind the tail lights.

Bill Robertson
#5939

kings1527
09-24-2013, 06:15 PM
Thanks Bill. And are splices supposed to be made in both locations? Or either/or?

Greasy DeLorean Mechanic
09-24-2013, 06:24 PM
Depends upon which sidelights the owner wanted to flash. I flash all 4 myself, but some Euro owners do the fronts only.

Bill Robertson
#5939

kings1527
09-24-2013, 07:07 PM
All four of mine flash, so I'll look in both locations I guess.

kings1527
09-24-2013, 11:11 PM
So I took a look. I undid all kinds of markers and couldn't find any splicing in any of the wiring. I put everything back together and tested everything, and now my side markers don't flash. I knew I wasn't crazy. Here's what I have:

Headlights and running lights on
-Turn signals work fine
-Side markers don't flash with ambers
-Everything's fine here

Headlights and running lights off
-Turn signals work fine
-Side markers don't flash with ambers
-Center running lights on rear markers flash on both sides when signals are used. They don't flash as bright as when the running lights are on, maybe 50% brightness which is interesting because they're LED.

I never had any issues before with all this. I still have to run through some stuff with an ice pick.

NightFlyer
09-24-2013, 11:47 PM
So the side markers were previously flashing with the turn signals and aren't anymore, but there's no modification to the side marker's wiring that you can find?

That's really weird and should technically be impossible (although with Lucas electrics, you don't rule anything out, including the impossible).

So the LED's in the running light position only illuminate at 50% of their intensity when the turn signals are engaged? Again, that's really weird and should technically be impossible, as even if power was being bled from the turn signal circuit to power them in conjunction with the signals, they should still be getting plenty of power for full illumination unless that power was encountering a good deal of resistance prior to reaching them.

Based on what you've told us, I'm inclined to think that it's a circuit board problem, or possibly a wire harness/connector/loom problem. The odds of both boards going bad at the same time is remote, but not entirely impossible, as a spike on the circuit could have wrecked the same traces or something.

kings1527
09-25-2013, 12:12 AM
So the side markers were previously flashing with the turn signals and aren't anymore, but there's no modification to the side marker's wiring that you can find?

That's really weird and should technically be impossible (although with Lucas electrics, you don't rule anything out, including the impossible).

So the LED's in the running light position only illuminate at 50% of their intensity when the turn signals are engaged? Again, that's really weird and should technically be impossible, as even if power was being bled from the turn signal circuit to power them in conjunction with the signals, they should still be getting plenty of power for full illumination unless that power was encountering a good deal of resistance prior to reaching them.

Based on what you've told us, I'm inclined to think that it's a circuit board problem, or possibly a wire harness/connector/loom problem. The odds of both boards going bad at the same time is remote, but not entirely impossible, as a spike on the circuit could have wrecked the same traces or something.

I know. It's a total psycho-car situation. Everything you stated is true. I'll have to look over the wiring again but there were no splices that I noticed immediately by any of the connections. Something may be hidden somewhere but I took a good look and wasn't able to find anything I didn't even disconnect anything. I simply jostled things around and put them back and now the side markers don't flash anymore.

Since the side markers will only flash with a mod, there has to be something somewhere. I have some circuit boards coming from Grady so that should rule out circuit board issues real quick. I'm really hoping that's the problem. I can't think of anything else that would cause it.

NightFlyer
09-25-2013, 12:45 AM
Since the side markers will only flash with a mod, there has to be something somewhere. I have some circuit boards coming from Grady so that should rule out circuit board issues real quick. I'm really hoping that's the problem. I can't think of anything else that would cause it.

But if there was a mod somewhere to flash the side-markers, then simply jostling them around shouldn't have reversed the mod - unless the mod job ranks right up with one of the worst hack jobs ever done unto a D :p

A crossing of some of the wires due to wearing or burned off insulation could cause the situation with the flashing running lights, or even a touching of the pins within a connector due to plastic that has melted or flaked off. Tracing the full length of the wires and checking the connectors are the only ways that I know of to check for these types of problems though.

Best of luck, as this is definitely a very baffling situation.

kings1527
09-25-2013, 01:02 AM
But if there was a mod somewhere to flash the side-markers, then simply jostling them around shouldn't have reversed the mod - unless the mod job ranks right up with one of the worst hack jobs ever done unto a D :p

A crossing of some of the wires due to wearing or burned off insulation could cause the situation with the flashing running lights, or even a touching of the pins within a connector due to plastic that has melted or flaked off. Tracing the full length of the wires and checking the connectors are the only ways that I know of to check for these types of problems though.

Best of luck, as this is definitely a very baffling situation.

Brutal. I'll have to take a look at the run of the wires in good detail and try to figure it out. FWIW, I've only seen a very few mods on my car (one or two) and there hasn't been any kind of surprises with anything. Def not like some of the nightmare cars out there.

To make it easy on me, I'll wait until I get my new Grady boards and install those first and go from there. I'm hoping there's something strange that happened to my originals and somehow causing this problem. From what I know with LEDs, they take a lot less power than the incandescents and maybe some weird electrical path on the boards is causing some power to 'spill' over to the running lights. I'm stretching but hoping.

NightFlyer
09-25-2013, 01:16 AM
Brutal. I'll have to take a look at the run of the wires in good detail and try to figure it out. FWIW, I've only seen a very few mods on my car (one or two) and there hasn't been any kind of surprises with anything. Def not like some of the nightmare cars out there.

To make it easy on me, I'll wait until I get my new Grady boards and install those first and go from there. I'm hoping there's something strange that happened to my originals and somehow causing this problem. From what I know with LEDs, they take a lot less power than the incandescents and maybe some weird electrical path on the boards is causing some power to 'spill' over to the running lights. I'm stretching but hoping.

Thinking about this further, I'm convinced that it has to be one of these three possibilities:

1) bad boards;
2) crossed wires (from loss of insulation and the wire actually rubbing together); or
3) broken connector causing the pins to touch.

Nothing else would make any sense what-so-ever - but the fact that the side-markers are no longer flashing with the running lights/blinkers is what has me baffled the most.

Again, best of luck and let us know what the trouble shooting eventually reveals.

kings1527
09-25-2013, 01:54 AM
Three solid ideas, Josh. Thanks for those. The DMC community never lets down. I'll let you know what I find out. Thanks again.

Greasy DeLorean Mechanic
09-25-2013, 07:40 AM
Do you perchance have an 1156 (single filament) bulb in one of the front turn signal / running light sockets (amber lights in the front bumper)?

Bill Robertson
#5939

kings1527
09-25-2013, 09:29 AM
Do you perchance have an 1156 (single filament) bulb in one of the front turn signal / running light sockets (amber lights in the front bumper)?

Bill Robertson
#5939

No. I'm fully converted to LED. Of course, with the exception of the battery light in the dash.

Greasy DeLorean Mechanic
09-25-2013, 09:46 AM
If you have single contact LED's in the front sockets, you've connected the turn signal and running light circuits together.

Are you absolutely sure the front LED bulbs have two contacts on the base?

Bill Robertson
#5939

kings1527
09-25-2013, 09:55 AM
Now, that I'm not sure of. I'll have to check on that. And sorry for the dumb question: what exactly am I looking for that would tell me I have double contacts? Thanks Bill.

NightFlyer
09-25-2013, 11:32 AM
Now, that I'm not sure of. I'll have to check on that. And sorry for the dumb question: what exactly am I looking for that would tell me I have double contacts? Thanks Bill.

1156's have a single contact point on the bottom of the base, while 1157's have two contact points on the bottom of the base.

http://www.hidkitreview.com/wp-content/uploads/2012/10/1156-1157.jpg

https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-snc7/405203_452486044783135_1211222060_n.jpg

Farrar
09-25-2013, 03:27 PM
I had a mysterious side-marker light problem once. It went away when I removed a defective LED unit which had been jostled to the point where there was a slight feedback problem. Try removing each unit in the parking light circuit one by one and see if the behaviour changes. It may just be a coincidence, but I thought I'd share my experience just in case. Good luck!

Greasy DeLorean Mechanic
09-26-2013, 12:52 PM
Something is connecting two originally independent circuits together.

A) PO mod (like flashing side markers)
B) Damage
C) Single filament bulb in a dual filament socket

My money is on A or C.

Bill Robertson
#5939

NightFlyer
09-26-2013, 12:59 PM
Something is connecting two originally independent circuits together.

A) PO mod (like flashing side markers)
B) Damage
C) Single filament bulb in a dual filament socket

My money is on A or C.

Bill Robertson
#5939

That's what I was thinking as well, but he said that it wasn't happening before and didn't mention changing any bulbs or modifying any wires, which is why I was inclined to think damage.

I like Farrar's point about faulty LED's causing weird problems, as that seems to be a regular occurrence (especially with the Chinese imports).

Farrar
09-26-2013, 02:53 PM
Also could be a combination of A and B -- "damage by previous owner."

kings1527
09-27-2013, 03:08 AM
Thanks guys. I read everything here and the first thing I'm going to do is install the Grady boards when they get here and go from there. It's gotta be something listed here and I'll find it. Ferrar - great advice and I'll definitely look into that. Thanks again for the help!

kings1527
09-27-2013, 08:51 PM
So I messed around a little bit today and I definitely have dual filament bulbs in the front sockets. So it doesn't look like that's the issue. I'm really hoping it's the boards and I'll know as soon as they get there. That'd be the easiest and least intrusive thing to do next.

kings1527
09-27-2013, 11:09 PM
So my Grady boards arrived tonight and I went down and installed everything. But the problem is still there. :-/

I haven't tried Farrar's suggestion and that'll be my next stop. I think I left my old bulbs at my work so I'll check tomorrow. Some things I was thinking about today:

-The side marker wiring mod didn't become popular until 3-5 years ago, correct? My car sat for about the past 5 years before I bought it. I haven't found anything funky that the PO had done to the car so I highly doubt I'm looking at a mod gone bad. I doubt he even did it and like I said, I've never seen my side markers flash until that one weird time.

-I'm wondering if I'm looking at a bad ground? Bill: according to your master ground diagram, it looks like the rear lights are grounded to the frame just below the expansion tank/coolant pipe on the passenger's side?

-What about a problem with the turn stalk? Probably unlikely?

NightFlyer
09-27-2013, 11:29 PM
Well, that sucks, but at least you have a spare set of good boards now :)

Definitely rule out a bad LED next. Personally, I'd do this by returning all the bulbs on the running and turn circuits to stock/OEM incandescents and see what you've got. Then you can narrow it down to exact bulb, if it's a bulb problem.

If not a bulb problem, you can check the grounds (always good to do anyway), but I don't really see how that could be causing the problem your experiencing. Same with the stalk, even more so than the ground.

The side-marker mod to make them flash has been around for a quite a while, definitely longer than 3-5 years, as it was heavily discussed on the DML and maybe even in back-issues of DeLorean World mag.

I'm putting my money on a bulb problem at this point, especially if you're running LEDs.

NightFlyer
09-27-2013, 11:56 PM
This problem on my car was caused by a faulty LED bulb


http://www.youtube.com/watch?v=32h22CzFRKc&feature=youtu.be

kings1527
09-28-2013, 12:00 AM
That's similar to what I've got going on and you could definitely think that could be a ground problem. Nice to know it was a bad LED.

Ok, great. I'll swap some bulbs as soon as I find them again. That seems like the next best step. Thanks again!

NightFlyer
09-28-2013, 12:15 AM
Had I realized that you were running LEDs earlier, that would have been my first suggestion, but for some reason, I glossed over that in your first post - sorry :(

kings1527
09-28-2013, 12:59 AM
No sweat! Thanks again for the help!

kings1527
09-29-2013, 02:10 AM
Totally random midnight thought: the ONLY place where I used cheap Chinese-made LEDs on my car were on the front turn signals. That's gotta be it. More info to follow next week when I'm back home.

NightFlyer
09-29-2013, 02:57 AM
They could definitely affect the running light circuit if one is bad - best place to start!

kings1527
09-30-2013, 07:57 PM
SOLVED

Bad LED! I put in a new incandescent 1157 bulb and the problem was solved immediately. It was my passenger's side front marker. Just for fun, I put the LED back in and sure enough, the problem came right back.

So no funky PO mod or bad board (even though I'm ecstatic to have some Grady boards in my car now).

Thanks again so much for all the help! Figuring this one out could've gotten out of hand if I kept going on my own!

NightFlyer
09-30-2013, 08:13 PM
AWESOME - Good to hear and glad it all worked out for you! :cool: