ElectroClassic EV
Classic Cars Reborn into the Electric Future

Bells and Whistles, Part 2

This post deals with the electrical accessories that needed a little more coaxing to make them work, including the turn signals, windshield washer pump, the parking brake light, and license plate lights.

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Incandescent at top, LED at bottom.

Turn Signals –  The turn signal switch talks to the flasher relay, and the flasher talks to the bulbs. The original turn signal relay only works properly when it detects a specific line resistance.  This resistance is measured across the bulb filament, and is represented as ohms.  Unfortunately, the replacement LEDs present an infinite ohm value, which looks like an open circuit and confuses the flasher relay.   However, as LEDs become more popular, retailers are beginning to produce aftermarket flashers that work specifically with them.

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Relay board with modifications.

One such relay, the CF13 GL-02 from  Autolumination was advertised to work with the Porsche 914, but didn’t.  TimK’s 914 blog explains how a couple of Radio Shack resistors and a soldering iron can fix it.  After popping off the cover and soldering in the new resistors, it still didn’t work.  This shifted me into diagnostic mode.  The clear fallback was to replace the stock flasher relay in the fuse panel, and restore all of the turn signals to standard incandescent bulbs.  If the stock configuration didn’t work, bigger fish needed frying.  No luck.  This led to another disassembly of the steering column to take a closer look at the turn signal switch, and to trace the circuit path.  I discovered accidentally that pushing the turn signal lever only halfway caused both left and right signals to flash properly.  A call to Auto Atlanta confirmed that the turn signal column switch was likely bad, and I ordered a replacement on the spot.

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Brand new turn signal switch.

Once the new turn signal switch was installed, it worked perfectly with the standard incandescent bulbs.  Since I knew that the original column switch was the problem, I switched all of the flasher bulbs back to LED to see if they would work with the modded flasher.  Unfortunately they didn’t.  When I activated the column lever left or right, the modded flasher clicked only once, and the signal lights stayed dark.  Still, the thought nagged me that there must be an aftermarket flasher for LEDs that works.

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Three Tridon relays and the CF13 GL-02.

I remembered a forum recommendation for a Tridon LED flasher relay, so in the name of science I bought 3 varieties of them at my local Auto Zone.  I had also become impatient with this whole issue, and wanted it resolved.  I got the relays home and popped them in the fuse panel.  Conclusion?  In the name of science, save your money.  None of them worked.  Here are some brief notes:  The gray EP34 on the left did absolutely nothing.  Both the EP35 and EP36 worked, but did not flash the dash signal indicator when the parking lights were on.  Worse yet, they caused the instrument illumination to blink on and off when the parking lights were off.

In the end, I stuck with what works: the stock flasher and incandescent bulbs for just the turn signals.  The rest of the LEDs work fine.  If I was really stuck on LED turn signals, the final option would require splicing a load resistor across each of the LED signal bulbs.  But then the whole point of energy savings would be lost.  This isn’t over.

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Modified washer pump switch

Washer Pump – An earlier modification to the new column wiper switch allowed the installation of an electric washer fluid pump.  The voltage to run the pump is shared with the wipers, and comes directly from the washer leaf contacts inside the new column wiper switch (pictured above).  After several blown fuses, lots of troubleshooting, and a bit of cowboy engineering, a short circuit was discovered and fixed.  Of course, a quick test was in order, so I filled the bottom of the reservoir with some washer fluid.  A tug on the washer lever started the pump humming and soaked the windshield as long as I held it.  Perfect.  It’s the simple things that bring such happiness.

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Apparently, Porsche owners need very strong reminders.

Emergency Brake Indicator – The switch that trips the indicator light on the dash is mounted under the emergency brake lever.  It’s activated when the lever is raised to engage the parking brake, and the unusually big red light goes on over the fuel gauge.  For some reason, the brake indicator stayed broken until the turn signal relay was fixed.  Now it works, but the brake indicator triggers the emergency flasher, and blinks very slowly.  I tried changing the LED back to the incandescent bulb, but it still does the same thing.  Maybe someone can confirm this is normal?  Thanks.

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P914 EV goes here.

License Plate Lights – This circuit continued to blow fuses whenever the parking lights were turned on.  After disconnecting the circuit supply wires from the fuse panel, my meter detected a short to ground all the way up to the LEDs themselves.  After unwrapping the harness bundle at the tail lights, I found the feed line crimped directly to the ground wire!  Undo.  In addition, the existing license plate lines were dried and cracked, so I spliced in a whole new set.  Now they work just fine.

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3 Responses to “Bells and Whistles, Part 2”

  1. Of course the EP34 did nothing, did not work, as it’s the wrong polarity.

  2. Hey Mark I had the same problem with EVIE and the LED lights I put in her. the solution was use all LED except for the dashindicator lights. They have enought resistance to activate the flasher.


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