53 Turn Indicator Bulbs (in dash) Both Flash

[Guy M.]

Re: 53 Turn Indicator Bulbs (in dash) Both Flash

I have the same problem with my turn signal dash lights. They both flash very dimly at the same time. I have a brand new LL harness and all the connections check out. If I read this right, do I need to ground the flasher case directly?

[Eric F.]

Re: 53 Turn Indicator Bulbs (in dash) Both Flash

There is no need to ground the case of an old or modern flasher. I know this because I disassembled both and discovered neither of the cases contact any of the internal components. The cases are simply designed to protect the internal components.

I also discovered it is important to make sure all the bulbs are the correct size and type. The bulb kit sold to me by one of the large corvette suppliers was incorrect; both in what they supplied and what their instructions designated. They said the turn signal indicator bulbs were #51; the correct bulb is #55. The rate of flash and intensity were effected by the incorrect bulb. I believe the 6 volt systems are more particular than 12 volt systems.

As I stated above, I'm still trying to sort it all out. I'll post the results within a day or two if everything goes well.

[Eric F.]

Re: 53 Turn Indicator Bulbs (in dash) Both Flash

Further research confirmed grounding the "P" terminal on a modern flasher will cause the dash indicator lights to flash independently left from right, rather than both together. However, this "fix" now causes the dash indicator lamps to flash at the same time as the exterior lights because they are now on essentially the same circuit. As I mentioned above, the case is isolated from the internal components so I didn't ground it.

So the "fix" eliminated the problem of both dash lamps flashing at the same time but modified the factory designed feature of the dash indicator lamps and exterior lamps alternating between flashing.

I'm still waiting to obtain a good (read properly functioning) old school flasher so I can test it too.

I'll report my findings.

[Eric F.]

Re: 53 Turn Indicator Bulbs (in dash) Both Flash

Mystery solved! I obtained a NOS Tung Sol 229 flasher and installed it tonight; it functioned as designed. The left and right dash lamps no longer flashed at the same. I did not need to ground the "P" terminal. As I suspected, the new style 535 flashers (solid state) work differently than the original (electro-mechanical). The original factory wiring harness and correct reproductions do not ground the flasher or the "P" terminal (black wire). The correct flasher will function as designed.

To clarify: if you are experiencing both the left and the right dash indicators flashing at the same time your problem is most likely the flasher. I suggest you find a NOS flasher, or at least one manufactured in the same manner, and avoid any of the new (modern) flashers commonly referred to as 535. If the 535 flasher indicates it was manufactured in China it will most likely be a modern solid state unit. If you cant find an old style flasher then you will need to ground the "P" terminal of the flasher for it to function like the old style flashers.

[Richard M.]

Re: 53 Turn Indicator Bulbs (in dash) Both Flash

Nice diagnosis and research Eric. Thanks for your efforts. You've certainly done a great job to solve this mystery.

[Guy M.]

Re: 53 Turn Indicator Bulbs (in dash) Both Flash

Eric, this is GREAT work and we all appreciate your efforts! I have several NOS Tung Sol 535 flashers made in USA and I'm assuming these will succumb to the same problem. So how do I exactly ground the P terminal? What are the procedures?

[Eric F.]

Re: 53 Turn Indicator Bulbs (in dash) Both Flash

Guy, If you have NOS Tung Sol 535 Flashers made in the USA I doubt you will encounter the problem. My tests revealed it is only the newer import made 535 flashers that caused the problem. The way to determine if your flashers are the old versus new style is to simply plug them into the flasher socket and then turn on either turn signal. If both dash indicators flash then the flashers are the new solid state style.

Assuming you have the solid state flasher that requires a ground on the "P" terminal of the flasher then you could solder maybe a 3 " black 18 gauge wire to the black wire terminal in the flasher socket. I would solder a ring connector to the other end of the 3" wire and attach the ring to the screw used to fasten the flasher socket holder to the lower part of the dash. I must say that I would go to great lengths to find a correct flasher before I would modify an original harness to accommodate an incorrectly designed flasher; such as the new imported 535 flashers.

I've attached a photo that shows the differences between the correct (old) style flasher and the incorrect (new) style flasher. The flasher on the right is the new import style and shows the transistor; which requires the ground in order to function properly. The other photo shows the new style flasher before I disassembled and tested it.

I hope this helps others avoid the 12 hours of wasted time I spent chasing a wiring problem that didn't exist. Funny how sometimes we (I) forget to check the simple things first.

[Gary H.]

Re: 53 Turn Indicator Bulbs (in dash) Both Flash

Another thing to keep in mind is the difference between original, on left, and reproduction sockets, on the right, that come with some new wiring harnesses. The original is wired with the black wire in the center and the blue wire on the clip, that is insulated, the clip on the repro. as you can see is not insulated. I had a problem until I replaced the repro. sockets with originals.

[Eric F.]

Re: 53 Turn Indicator Bulbs (in dash) Both Flash

Yes Gary, I had the same problem. I blew 3 fuses before I discovered the reproduction sockets were shorting directly to ground.

[Guy M.]

Re: 53 Turn Indicator Bulbs (in dash) Both Flash

Well.........I plugged in two NOS Tung Sol 535s (Made in USA) and they didn't preform well at all. The third one was better but fizzled to dim after about 45 seconds. I do have a new LL harness and maybe the sockets are the culprit. Not blowing and fuse though. All the grounds are in place according to the schematic. beats me.

One other question unrelated.....if there is no continuity between the posts of the E-brake flasher, does that mean it's shot? I think so but not sure.