I need some help with my electrical, so calling out to all the electrically minded individuals on the World. After an extensive rebuild of the front suspension, I took the car to an alignment shop. When I returned, about 1 1/2 hours later, I found that they couldn't get the car started. I had just replaced the starter with a rebuilt unit from Autozone. It was working perfectly. There was power to the starter but it wouldn't turn over. So..they bridged the control wire to the starter, and it turned over and started. For fear it wouldn't start again, they left it running while the finished the alignment (10min). When I got home, the car again would not start after turning it off. I preceded to check the electrical next to the starter. Everything checked out. When I tried to start it, I could hear the fuel pump change sound like I was getting a draw on the battery (pulling amps). No sound from the starter/solenoid. It was then that I noticed a smell from the engine compartment. I looked and disassembled everything and couldn't find the smell. So I attempted to do the same thing and turn the ignition on and bridge the control wire to the starter. After 15 sec. I quit and turned off the ignition. I then saw a lot of smoke and found that it was coming from the distributor. I fried the Pertronix ignition. How would that be related? Any thoughts on how to remedy this perfectly horrible car day would be appreciated.

I realize now by bridging the 12v lead to the control wire, I put the voltage back into that line. It obviously fried my ignition. What else did I likely destroy? What is upstream of the control wire?

I realize now why I picked my Avatar. Destiny!

I'd start at the starter solenoid. It has power all the time from the battery. But do you get voltage on the ignition wire when you twist the key?

Are you running a hot start relay? It's been pretty hot here in PDX the last couple weeks. With the traffic and hot pavement ..............

If it turned over when the starter was bridged it is not the solenoid as that is required to push the starter gear out. You have low current/voltage through the starter switch. You can confirm this with the help of a friend putting the key in the start position and you under the car with a volt meter. However, it is easier and recommended that you just install a hot start relay a the starter. It takes the load off of your old wiring and ig switch.

I thought the early Pertronix modules were susceptible to damage if the ignition was left on with the engine not running.

The Pertronix has a transistor which turns on and shorts the NEG of the coil to ground so the coil can store energy and be released to fire the spark plug when the transistor turns off. The coil inductance limits the rise in current during the short periods when the transistor is on and the engine is running.

If the engine is not running, the transistor is on and the coil current is now limited by the resistance of the coil and resistance of the transistor. Both get hot and the transistor can be damaged.

I thought later versions of Pertronix solved this issue by limiting the amount of time the transistor could be on.

Are you sure the problem is not at the key/ignition switch? They can both go bad.

I think it is highly likely that the ignition was left on. I'm not sure how that would relate to not getting the power to the starter??

Ordered a new switch.

Can someone explain to me why I would get a draw on the start mode (pulling amps) and the solonoid not kicking over with no sound from the starter? What is drawing power? Is there a minimum voltage at the solonoid that allows it to kick over?

Solenoid needs a good, strong voltage and current or it will not budge. That is why the relay is a good addition as it routes the battery straight to the solenoid and the relay needs less power to close.

+1 on the relay. Where are the naysayer's?

I can't believe they didn't come from the factory with a relay......now that I know this I'll be taking care of that oversight when it comes time to wire mine up. If you have a test light use it instead of a volt meter, volt meters are good but can SOMETIMES trick you. a test light will give you a good indication of decent current.....or lack there of.

nine9three,
Your avatar truly does fit.
The contact where the large yellow wire goes on the solenoid is terminal 50. This is the contact that when 9-12 volts at 35 amps is received, the solenoid does two things.
1- throws out the bendix to engage the starter gear to the flywheel
2- bridges the two LARGE electrical contacts at the back end of the solenoid to provide battery power to the starter motor.
It sounds like you have an issue somewhere in the starting circuit between the battery and the solenoid terminal 50. Could be anywhere, key switch, seatbelt interlock, wiring, or connections.
The Pertronix burning up probably had nothing to do with you bridging the solenoid. I say probably because it definitely would not on a stock car with no wiring changes. If a prior owner has done some wiring changes, then that could change everything.
Others are saying use a relay because 35 amps thru your key switch is not a good idea. A relay will only draw 1 amp or less.
Hope this helps, and keep dem forks away from dem sockets,
Tom

The car is 100% stock no modifications to the wiring. After looking at the wiring diagram. By bridging the control wire 50 to the battery terminal 30, I have essentially sent power back into the the circuit all the way to the fuse panel at fuse #9. If I follow fuse #9 back into the loom you will find that one of the wires enters the auxilary fuse panel in the engine compartment wire#8. Through the auxilary board and out wire #7 which terminates at the coil. Could this have fried my Pertronix? Maybe.

Order 2 they are cheap & it is a must to have a spare in the glove box

nine9three,
Since your car has no wiring mods, then No, you won't send power back to fuse 9. The key switch has 3 positions. The start ( or third ) position is the only position where the yellow wire to terminal 50 is powered. I had double checked the schematic to be sure before I posted an answer to your question, that is why I said there was no way to feed back power in the ON position with a car that had stock wiring. When the key is to ON, the power would go no further than the key switch. Otherwise, the starter would be energized whenever the key switch is to ON. I assure you that that would be a very bad thing. Fuse 9 is already powered when your key switch is to ON. Pertronix modules are known for frying when power is applied and the engine not running.
Haynes book, page 122, Fig. 9.5.
Tom

Reversed polarity or leaving the key in the "on" position for longer than 30-40 seconds will fry the unit.

From PerTronix website:

What will happen if I leave the ignition switch on when the engine is not running?

Leaving the ignition switch on when the engine is not running, can cause permanent damage to the ignition system, and related components. This does not apply to the accessory position of the ignition switch.

That's well known and likely what happened at the shop. There is no accessory position on a 914 switch.

So what I found so far. I checked the control wire from the switch back to the starter. I had 0 ohms from the switch to the auxiliary fuse board but no connection from there to the starter. I found that my loom connected the Aux. board was loose.
After tightening that lead I got power to the starter. I pulled the fried Pertronix and replaced it with points and got the engine to fire/hit. The wires all appears to be good and the Pertronix to the brunt of the damage. In other words no hot or damaged wiring. But as I attempted to start the car again after rotating the distributor, the starter again would not turn over. It was then that I could hear a frying sound from the ignition switch. Everyone needs to do themselves a favor and open up that little POS to take a look. I ordered the hot start relay, and, everyone should. I don't know what Porsche was thinking. I will give an update when I get everything back in order. No question in my mind that bridging the control wire to the battery wire on the starter fried my Pertronix. Whether that happend through reverse current into the fuse panel or at the switch, it happened. For reference in the future If i got in a jam and had to start the car because of a bad control wire, I would remove it from the solenoid before I bridged the terminals. Hopefully when the new ignition switch and hot start relay is installed, this will never be an issue again. Still a little nervous about putting in a brand new Pertronix. Maybe I will stick with points for a few days just to make sure.


JRust you are right, and I should order a couple of these. You should think about a quick disconnect for your battery before you get back your flamming .

Did you read post 17?
With the key switch to ON, it is impossible for current to feed back to fuse 9!
Tom

Tom,

If the switch is defective/broken and is arching inside I think anything is possible. I did look at the wiring diagram as well.

Get a Ford relay and for future reference, yes you can jump with the yellow wire connected.

993,

Your switch won't "arch" inside. The construction of the switch makes it extremely difficult for things to connect when they aren't supposed to. The noise you hear is almost certainly due to contacts that should be cleanly connecting, but aren't (due to their being burned).

'Jumping' the starter when the ignition is already on can't cause damage to the vehicle.

Leaving the ignition on *after* the Pertronix module has failed can (depending on the failure mode) result in assorted other bad things happening (including nasty smells, smoke and possibly fire).

The switch was designed for a ten-year service life (the norm for the era). The fact that many are still working well 45 years later is something you should be happy about, not cursing...

[quote name='nine9three' date='Sep 11 2014, 10:58 AM' post='2084754']
So what I found so far. I checked the control wire from the switch back to the starter. I had 0 ohms from the switch to the auxiliary fuse board but no connection from there to the starter. I found that my loom connected the Aux. board was loose.

So even with your yellow wire open from the the aux fuse panel ( it's the relay panel or regulator plate - Haynes ), bridging the solenoid control yellow wire to the battery wire burned up your ignition unit.
Sorry, can't buy into that!
And just for information, the black stuff you see in the ignition switch is caused from arcing contacts and is most likely copper oxide. Copper oxide and carbon are a better resistor than a conductor.
Tom