Saga of Dottie - Electrical Gremlins

[Phydous]

Hey All, I am getting really close to having my '69 baja ready to daily drive. While the car is far from finished, I have two things I still need to resolve before I can use her for daily driving to and from work. (~5 miles each way)

Ashman40, you out there?

Issue 1) The engine starts right up and runs great. The problem is that when I turn the key off, and even remove it from the ignition, the engine continues to run. Not dieseling, it's running. I can even remove the negative, and positive connections from the battery and it continues to run.

I have an MSD 6 Offroad multi-spark and an HVC II Blaster coil. Somehow it's like the alternator is continuing to feed the positive lead to the MSD which turns on or enables the MSD to start sending power to the coil. And, it also must be feeding power back through the lead that runs from the battery to the MSD.

Do you think I have a bad ground somewhere? Do I need a solenoid or diode somewhere to stop the back power back feed?

Issue 2) I thought I had all of my lights working, but I still have something going weird. Currently, everything works just fine on its own. Park lights work, Running lights work, brake lights work, flashers work, and turn signals work. The problem is when I have the running lights on (works) and either blinker on (works) but then I apply the brakes, so running lights, brake lights, and blinker all on at the same time, the light will stop blinking and go into an intermittent pulsing mode, occasionally going completely dark. It's the strangest thing.

Anyway, if anyone has thoughts or ideas on what I should look at I would greatly appreciate it!

Thank you!

[Pops67Beetle]

The issue with the blinkers is most likely a poor ground in any of the light housings. Take them apart, one by one, and clean all of the grounds. I would bet that if you just use the turn signals in a dark spot you will see another lamp dimly light up.
_________________
When I close my eyes I’m a little kid riding in the cubby..... Priceless!
13 y/o son’s quote while watching us replace the pedal cluster…. “Who says the Germans lost the war.”

67 Beetle bought new, 95% stock.

[61SNRF]

Looks good! '69 is a great year for a Baja.

1) Not sure. The VW's electrical system is not unique or peculiar in any way.
I would suggest reviewing the MSD install instructions, I believe there should be a terminal for a +15 switched power supply from the iginition switch. That or call their customer service desk for assistance.

2) Since the VW uses it's steel fenders as a ground path for the lighting, and your's are now fiberglass, what you need to do is run a dedicated ground wire from the main body to each lamp fixture.
_________________
-Bruce

An ounce of prevention is worth a pound of cure.

[Phydous]

Thank you for the suggestions. I will try them and report back.

[ashman40]

Issue 1) I have seen what you describe when a relay is added to power the ignition switched circuit #15. For example, the ignition switch voltage that makes it to the ignition coil (or MSD in you case) is a bit low. So in the engine compartment, you add a simple Bosch-style relay. It is energized by the ignition switch (#15) wire. It then sends battery voltage directly to the ignition coil #15 terminal. From a high level view this would seem like the right thing to do. The logic is slightly flawed because it assumes that the ignition switch is the only source of power for the #15 circuit and when you turn off the ignition switch the relay will also turn off.

The issue has to do with the alternator D+ (GEN lamp) circuit (it may also happen with the generator #61 circuit). At the instant your turn the ignition switch OFF, the ignition switch is no longer providing any current to the #15 circuit so you would expect the voltage on this circuit to drop to zero, but it doesn't. For the second or two that the engine is still rotating the alternator is outputting 12v+ on the D+ wire to the GEN lamp. While the ignition switch is ON this current from D+ is balanced by current from the ignition switch. But when you cut the current from the ignition switch the current from the D+ wire thru the GEN lamp will attempt to power the entire #15 circuit (which includes the #15 wire to the ignition coil). You see this as the GEN lamp glowing the instant the key is turned OFF while the alternator is still rotating. This current from the alternator passing thru the GEN lamp shows up on the #15 ignition circuit as a low voltage (~6.0v). Normally, such a low voltage will not power anything on the ignition circuit... but a typical Bosch SPDT relay will continue to operate with only 5.0-6.0v. So your relay remained energized and continues to provide a constant 12v from the battery to keep the ignition running. If the ignition is running the spark plug continue to fire and the engine continues to run. Anything else run from this same relay power circuit will also see full battery voltage and remain ON while the ignition switch is OFF.


Test: With the engine running, remove the GEN lamp holder from the speedometer and wrap it in a rag so it does not short to ground. Now turn off the ignition switch and see if the engine stops as soon as the key is turned OFF. With the GEN lamp disconnected if your ignition/engine act normally you have isolated the issue to the current flowing thru the GEN lamp.
If you find this is the case, you can choose to remove the relay from the ignition circuit powering the ignition coil/MSD. Or, another option is to add a small 1A diode at the GEN lamp wire. Orient the diode so this will allow positive current flow from the fuse box to the alternator, but prevents current flow backwards from the alternator to the ignition circuit. This stops the current flow that is keeping the relay energized, but will also prevent the GEN lamp from glowing when your battery is weak or your charging system is over charging. In both cases current flows from the alternator D+ to the fuse box and is indicated by the GEN lamp turning ON (glowing). The GEN lamp will still tell you when the charging system is undercharging.


Issue 2) sounds like a grounding problem. Check the ground wire at each corner making sure there is zero resistance between the metal frame of the light assemblies and the chassis ground. It really sounds like your turn and parking lights may be grounding thru the brake lamps.

One way to test this is by using a jumper wire with alligator clips at each end. Remove the lens from each light assembly. Ground the metal frame of the light assembly to a known good ground point and retest that side light. Repeat for all four corners. If the jumper wire makes a difference it means that light assembly is improperly grounded.

Good luck!
_________________
AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[Phydous]

[Phydous]

[61SNRF]