Accessory Mode for the VW -Save your Pertronix

[AirHead1966]

I burned out a Pertronix electronic ignition module in my 009 distributor due to power to the coil wire without the engine running. I know some people like points but I like the Pertronix module and bought a new one.

I started thinking about adding an "accessory mode" that would protect my new Pertronix electronic ignition and would let me keep the accessories on.

I could have added a switch to control power to the coil/Pertronix but that a is manual step and if someone else is driving my car, they would not know about that switch.

So, here a simple little circuit I came up with that uses the starter trigger to signal a relay as to when to power the coil. Once starter is done, the other relay keeps the coil powered until ignition is turned off.

The net effect is that once you turn on the key, coil has no power; only accessories have power. Car can be left like that for any amount of time without damaging the Pertronix. When you crank the engine with the starter, the coil/Pertronix gets powered and remains powered after cranking is done.

[Dale M.]

[tattooed_pariah]

Can I ask why you are sitting with accessories powered for an extended period of time?

The only thing I can think of is the same reason I used to, to listen to the stereo in the car (I always get places WAAAY earlier than I need to be there).. My solution 20 something years ago was to just wire the stereo to a circuit that hot all the time. I have a detachable faceplate, so I just remove the face to turn it off..
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-pariah (just a novice from "that other VW site")
'72 Volksrod "Effigy"

"Never worry about stepping on people's toes. People who get their toes stepped on are either sitting down, or standing still on the job."
-Admiral Arleigh Burke, USN(ret.)

[AirHead1966]

[tattooed_pariah]

[74 Thing]

Ignitor II addresses that problem
https://pertronixbrands.com/pages/pertronix-ignition-electronic-ignition-conversions

[AirHead1966]

[mikedjames]

This is clever - it will also turn off the choke power, so the engine is using zero power until you turn the key to start.

BTW there is a simpler version using two diodes and a single relay. I sketched it here - the diodes steer current to the coil of the relay either from the starter wiring, or from the output of the relay. Turning off the coil feed will de-energise the relay as with two relays.

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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[AirHead1966]

[mondshine]

I did this a different way.
My radio, glove box light, heater, and garage door transmitter are all powered by a relay that is triggered by the SU contact in the ignition switch.
On my '73 Thing, the SU contact provides a ground connection with the key in the ignition, but with the ignition switched off.

On some models, the SU contact is used to power a buzzer when the key is in the ignition switch and a the driver's door is open.

Like this:

Good luck, Mondshine

[AirHead1966]

[allamaabroad]

Ingenious use of a 2 relay memory circuit, good thinking and well done! What's interesting is with the use of an industrial style relay, you can actually accomplish the same task using a single relay
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Dennis - 1973 Super Beetle ('16-'21)
Debbie- 1970 Baywindow Bus ('21 - Present)
Tin top camper/adventure bus

2180 TW: CNC Panchitos, Beehives Done Right, Web 163, Ultralight Lifters, 1.3 Rockers, CSP Python, Custom Speeduino EFI Conversion with 40mm Throttle Bodies

Distributors are lame

I have a really hard time leaving things alone...

Innovative and affordable engine management systems and EFI conversions for your Vintage VW
Visit https://debbiesaircooled.com/

[bsairhead]

[jeffrey8164]

Maybe it’s just me but I’ve been using the accessory circuit as delivered stock for the life of my VW’s and I’ve never had a problem leaving the key on to play the radio or whatever and been using Pertronix modules since ‘91
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Volkswagen!
Turning owners into mechanics since 1938.

“Let he that is without oil throw the first rod”
(Compression 8.7:1)

[BFB]

holley and a couple others make an oil pressure switch that does about the same thing. no power to [ coil , fuel pump, pick your poison ] without oil pressure, i believe switched at 5 or 7 psi. start wire jumped to this switch powers your poison at startup until oil pressure is above the 5 or 7 psi point at which point main power takes over.
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Forced induction can overcome a lot of obsticles that gets in it's way
"You are the Engineer and the Mechanic.  
Build it your way not the way someone else does it. Their way might not work for you." - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
“ The monkey see monkey do mentality seems to run deep in VW people. "Gene Berg said it was so 30 years ago so thats the way it is" “ - bdkw1

[balljoint]

[Glenn]

Why not just wire things to bypass the key?

That's the way VW did the radio.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

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[AirHead1966]

[AirHead1966]

[Glenn]