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Discussion Starter #1
Due to poor workmanship and numerous intermittent electrical problems, I gutted my MKII and rewired the car with a customizable 22 circuit hot rod harness from Speedway Motors. Each headlight, front running light, and each of the four Lucas 691 tail lights is terminated on its own 3-pin Weather Pack connector. Splices, like the ones for the front and rear running lights, were made using bare metal, in-line crimp sleeves that were dressed with appropriately sized heat shrink. All wire runs were wrapped with appropriately sized Alex Tech braided, split-side, self-wrapping wire loom, and was also dressed with heat shrink, as needed. All connectors were tested and voltages confirmed, using a grounded voltage probe. Additional Weather Pack connectors were used extensively behind the dash and center gauge cluster, so the center gauge panel could be removed as a self-contained unit, if maintenance ever needed to be performed. I wouldn’t have to unmount any switches or controls. I’d just have to unplug a few connectors. Every wire it labeled as to its color, its number in the wiring diagrams and its function. I was taught never to power components through their On/Off switches. I was taught to power things using relays, and use their switches to control the relays, which is what I did for my turn signals. I installed two relays that I got from Painless Performance Wiring. They come with 8-foot leads pre-connected, so installation is fairly fool proof..

I took the output power from the 2-prong flasher, and connected it to PIN 30, which is the battery. A fused 12V switched power feed was connected to the COMMON IN on the turn signal control stick. The right and left turn signal outputs were wired to PIN 86 on each relay. PIN 85 on each relay is wired to ground. The output of each relay (PIN 87) was spliced to provide two (2) outputs for each side of the car. One for the front signal lamp and one for the rear. Those two lamp connections were made to the two corresponding power connections coming from the relay, using a single 2-pin Weather Pack connector for each side of the car. With none of the signal lamps connected, I confirmed 11.7V on each power output pin, from each of the relays. When I connect either the front or rear signal lamp and operate the control stick, the one connected lamp illuminates just fine, but it does not flash. If I hook up the other lamp for that same side of the car and test it. It also lights up just fine, but it too does not flash. If I hook up both the front and rear signals at the same time, only the rear lights, and the voltage at each lamp drops to only 6.3 volts. I’ve tried several configurations, including trying the turn control stick both as a power side trigger control, or as a ground side trigger control. No matter which way I’ve tried it, I can’t get anything to flash, and I don’t know, what to do about the voltage drop. There are three ground points for the entire car: one on the frame front “K” support member, one for the rear of the car in a frame member above the gas tank, and the third for everything in the cockpit. The only thing I have not yet tried, it to add two more relays, and to power each of the four turn lamps from its own relay. That may fix the low voltage problem, but I don’t know if the low voltage is also affecting the flasher. I’m open for suggestions.

Mahalo and aloha from Hawaii.
 

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Why are you adding relays to the turn signal circuit? The thermal flasher (I'm assuming that's what you're using) is, in effect, a relay and is designed to handle the current of the lights. That's in fact what makes it operate. Relays are intended to switch high current with a low current trigger. But not needed in this case. I didn't dig deep enough in your description to offer more, e.g. about the voltage drop. But the added relays are redundant and in fact could make the circuits not operate correctly. That's my take. BTW, if you have any intention of running LED's, you may want to consider solid state flashers rather than thermal.
 

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Not sure where you got your advice about switches and relays, but it's incorrect. Relays are only needed where you have a high load, or the devise is switched by a micro circuit (computer). The switches are designed to handle the rated load. You can't use a relay on a turn signal, the flasher will not operate. Flashers are load relays, trying use a relay with them does not supply the LOAD to activate them, get rid of the relays and the flasher will work. As for the voltage, somewhere you have something miss wired, you are using the ground side of a load to try to power the next load, you have it in series, not parallel, thats why you're seeing 1/2 the voltage.
 

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Two questions: (1) are you using LED bulbs; (2) are you only using one bulb per side (in the rear) for turn signal?
IF you are using LED's, you need to also be using an "electronic" flasher as the older style "thermal" type will not flash with LED's - not enough current draw to activate it.
IF you are trying to use both upper and lower as both brake AND turn signal, you will absolutely need relays (or a trailer adapter) to get that to work correctly.
IF you have the newer style rectangular tail lights supplied by F5, they are LED, or so I've heard . . .

Your circuit should be 12v power ---> flasher, output of flasher ---> to pin 30 of relay controlling one side of the car. This feed can be split to feed the other relay for the other side of the car. Front, Rear and Dash Indicator connect to pin 87 ---> ALL bulbs grounded. That's the flashing part.
Activation part is: switched power ---> to center (common) lead of stalk switch ---> output (either right or left lead) goes to pin 85 (or 86) of relay, other pin 86 (or 85) to ground. Relays are non directional (on coil activation) so either 85 or 86 can be used as input.

Hope that helps . . .

Doc
 

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Discussion Starter #5
To reply to everyone’s questions:
Why I used relays. This being the first time I attempted to rewire an entire car, I went to what was drummed into me by old school racers and high performance engine builders, who were among my friends. That pretty much was, when in doubt, power it with a relay, rather than the switch. Add that to the fact that the manufacturer of the after-market turn controller I have, advised me to use a relay, because the switch was only rated for 3 amps. Before starting work I researched 20 or 30 “How To” videos on You Tube, and a number of them talked about turn signal switch contacts being a common failure point, and that using relays would make a far more robust system. Also, when I put in the relays I had not yet made the conversion to LED bulbs.

Yes I replaced all the incandescent lamps with LED lamps.

Yes, when I made the switch to LED bulbs, I changed from the bi-metal mechanical flasher relay can to an electronic flasher that is supposed to be LED compatible. Whether or not it is considered “Solid State” I don’t know.

NO I did not keep all the rear lights wired together. I have the bottom pair wired with both the low filament for running lamps, and the high filament for brake lights. They contain red LED bulbs and function correctly. I ran a second pair of power leads and grounds to the upper rear pair, and that second set of leads is wired to the high filament only and is strictly for the turn signals. The upper pair of lamps is fitted with amber LED bulbs and once the replacement amber bezels arrive, I will swap out the red bezels.

I’ll start at the lamps and work my way back to the flasher, and eventually I’ll find the root cause of the voltage drop. I thank you all for your comments and advise. Keep you all posted, after I resume troubleshooting tomorrow.
Mahalo nui loa
 

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Discussion Starter #11
Here’s the latest. I was able to track down the voltage loss to the LED replacement bulbs I was using. With the initial set of red LED bulbs installed, my voltage was dropping from 12.4 VDC to less than 6 volts. With that much voltage drop, none of the 4 signal lamps would even come on. When I replaced the red LED lamps with amber ones, which are required to convert the upper pair of rear lamps to turn signals only. The voltage drop went from 12.2 to 11.4 volts at each signal lamp. Now when the turn signal control stick is operated, the correct pair of signal lights, comes on, along with the associated dash indicator lamp. The problem is, that they stay on constantly and do not flash. I’ve tried 3 different flashers, all of which were 2-prong electronic flashers, and the result was the same with each.

The power path to the signals lights is:

Ignition power to fuse block and 10A Turn Signal Fuse, to included Turn Flasher
Flasher Out to Turn Signal Control Common Power IN
Turn Signal Control Unit Left and Right outputs are spliced, so each feeds three (3) each single pin Weather Pack connectors, going to front, rear and dash lamps on each side of the car

I have ordered two (2) different types of 2-prong solid state flashers, to see if they make any difference, and I also ordered two (2) types of 3-prong flashers, to see if using a grounded flasher makes any difference.

Any suggestions anyone can offer on the lack of flashing are greatly appreciated.
 

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Discussion Starter #12
Good new. I replaced the one type of electronic flasher I had purchased, with a solid state one, and I now have fully functional turn signals that work perfectly, So the wrong LED bulbs and the wrong flasher were the source of all my problems. Thanks to all who contributed.
 

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Buy a spare. At least on a MKIV, guess where the water goes if you don't get the windshield post sealed up? I went through 3 or 4 before I got under there a finally got it sealed.
 
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