Problem with left turn signal and side indicator lamps

[tstewart]

Just developed an issue with my '73. Drove it yesterday for the 1st time in about a month and when using the left turn signal, the indicator in the dash illuminated solid as if one of the turn signals were blown. Went out to check it out today and when I turned on the left turn signal, it began working but flashing slightly more rapidly than usual. I also noticed that the left side indicator lamps have begun flashing in alternation with the left turn signals (as the flashing signal goes out, the side marker illuminates and vice versa). This only happens on the left side. Additionally, the right turn signal actually blinks almost imperceptibly with the left. There are otherwise no issues with the right signal.

I was taking the car for a test drive after replacing all the fuel hoses at the fuel tank. During that process, I had the fuel tank connectors loose. More importantly, the left brake light was blown, so while I was there, I replaced it. The brake lights work fine now but could there be a relationship?

Edited August 17, 2009 by tstewart

[EScanlon]

More than likely you have inserted a 2-filament bulb into a 1 filament socket or vice-versa.

FWIW

E

[mike's78z]

I've been having a somewhat similar problem. However the left turn signal on my car stays on solid and doesn't make any clicking noise. The right turn signal works fine. Also the headlamps won't turn on. I'm fairly new to the Z so if you find out what thev problem is let me know. thanks in advance,

Mike

[FastWoman]

Your turn signal won't flash if either one of the signal lamps (front or rear) is out. If the rear one stays on solid, check the front to see if it's out. The third lamp, of course, is the dashboard indicator light. Check that it's working too.

Headlights are electrically another matter. Check your grounds. The high/low beam switch should have a good, beefy ground (black wire) on the other side of a 6-wire connector. Check that the contacts in the connector aren't burnt. On the other end, electrically, your headlights and signal lights draw their +12 power from one of the brown fusible links (don't know which one). Because your signal lights are working (sort of), I doubt this is the problem. However, check your voltage at the battery, at the fusible link, and at the left top two fuses in the passenger fuse panel. That should all read the same. If there are any significant voltage drops between these points when the lights are on, you'll know you have a faulty connection somewhere. In all likelihood, you'll have some very corroded crimp connections in the wiring tree on the righthand side of your engine compartment. Aside from the +12 from the fusible link and the ground on the other side of the high beam switch, everything else runs through two different circuits (fed by the above two fuses). Multiple things would have to be out for your headlights (both of them) not to work, but that's quite plausible too. My guess is that it's the ground wire off of the high/low beam switch.

If you find that your connections and/or switches are getting too crusty and unreliable, you might do as I did. I wired my headlights to relays, taking most of the current load off of the (precious) combination switch. This sort of work isn't for the electrically clueless, but it's not rocket science either. Do you need 1978 wiring diagrams, or is this a job for your mechanic?

[mike's78z]

OF COURSE THE HEADLIGHTS DON'T WORK IF THERE'S NO BULBS!

Sorry, i bought the car w/ the impression that the headlights were there. I test drove it during the day so i forgot to check. Stupid me....

The drivers side turning signals both light up, but they stay on solid. Like the other person, my dashboard light stays on solid as well. My knowledge of electronics is limited to logic gates and what not. However I can follow directions if they're detailed.

I keep reading about fusible links, what are they and what do they do? Is it some sort of wire that burns when it exceeds the voltage?

[nahurry]

http://www.classiczcars.com/forums/showthread.php?t=35299&highlight=electronic+flasher this is worth checking out! my 73 had turn signal issues also, and now it's perfect.

[bpilati]

More than likely you have inserted a 2-filament bulb into a 1 filament socket or vice-versa.

FWIW

E

I don't kniow about that E, those bulbs usually have off axis tabs on the side so you don't install them incorrectly. How about the flasher unit under the dash, or a ground?

[FastWoman]

Mike, the fusible links are those wire loops with female spade connectors on the ends that are connected inside the two little (2" x 2"?) plastic assemblies on the passenger side of your engine compartment. The assemblies are mounted to a larger (6" x 6"?) black box, which is mounted to the inner fender. (Your various major relays are located inside the black box, BTW.) The fusible link assemblies have little white covers over them that typically turn very crumbly and might even be missing.

Anyway, a fusible link is simply a funky, ultra-slow-blow fuse. It's a length of wire that is about 2 gauge sizes smaller than the wire they're protecting (e.g. a 16 gauge fusible link wire to protect a 14 gauge line). Mine were all crumbly and awful, so I replaced them. The project is documented here...

http://www.classiczcars.com/forums/showthread.php?t=35588

I have photos towards the end. My new fuse block assemblies are mounted where your fusible link assemblies would be mounted.

[a7dz]

I got water into one of my tail lights do not know how and had the same problem. Cleaned up the socket changed the bulbs and all is good again.

[EScanlon]

I don't kniow about that E, those bulbs usually have off axis tabs on the side so you don't install them incorrectly. How about the flasher unit under the dash, or a ground?

I would agree, except that it has happened numerous times here on this board and others. The bulb socket gets old, people shove the bulb in and out and before long it allows a sloppy fit on the bayonet base... and the bulb can be inserted incorrectly, or even an incorrect bulb.

I've seen cars with really bright running lamps and barely noticeable brake lights on one side... check the bulb and it's in there 180° off. That's using the proper bulb just inserted wrong.

Single filament bulbs (1156) have one contact that bridges BOTH contacts that power a dual filament bulb (1157) and you get turn signals at the dash turning on when you press the brake, front marker lights acting as brakes, and really funky operations when using the turn signals.

It could be a bad flasher unit. Swap the Haz for the T/S and it's an easy check. But as Jim (a7dz) mentions, a simple "short" in the bulb base caused the same problem, his was due to water.

In the original post:

the left side indicator lamps have begun flashing in alternation with the left turn signals (as the flashing signal goes out, the side marker illuminates and vice versa). This only happens on the left side. Additionally, the right turn signal actually blinks almost imperceptibly with the left. There are otherwise no issues with the right signal.

The problem is reminiscent of the Side Marker Upgrade connector which connects the side marker to the Turn Signal Circuit AND the Marker Light Circuit... the end intent being that the side markers blink on when the t/s is off and vice versa. That Upgrade Connector takes advantage of cross connecting the circuits.

However, the indication that the RIGHT T/S is blinking "almost imperceptibly" says that it IS getting juice. That can only come from a cross-connection (short-circuit).

Then Tony continues with:

the left brake light was blown, so while I was there, I replaced it. The brake lights work fine now but could there be a relationship?<!-- / message --><!-- sig -->

Emphasis mine.

It often happens that when an otherwise "normally" operating item begins to malfunction, the problem can be traced to the last action taken. It isn't always definitive, but it happens often enough that that is the FIRST thing that should be checked.

Since he'd replaced a bulb, the solution I offered was based on that. Mistakes do happen, and sometimes it's the simplest that causes big problems.

FWIW

E

P.S.: On the subject of fusible links, here's a link... simplistic but nonetheless informative. I found the information on the SAE page, but you have to order the paper and it's not visible on-line.

Take a look at page 11:

http://www.autoshop101.com/forms/hweb1.pdf

The text there reads:

FUSIBLE LINKS

Fusible links are short pieces of a smaller diameter wire designed to melt during an over current condition. A fusible link is usually FOUR (4) wire sizes smaller than the circuit that it is protecting. The insulation of a fusible link is a special nonflammable material. This allows the wire to melt, but the insulation to remain intact for safety. Some fusible links have a tag at one end that indicates its rating. Like fuses, fusible links must be replaced after they have "blown" or melted opened. Many manufacturers have replaced fusible links with fuse elements or maxi fuses.

Emphasis mine.

[FastWoman]

My bad. Yes, it's 4 guage numbers, not 2.