Whats wrong with our ignition switches?, What do we know? Options

[chmillman]

So, following the excellent Pelican Parts instructions, I pulled the steering wheel etc. and took out the old ignition switch... Here's what it looks like:



So, definitely warranted replacing! In addition it was kind of oily, I suspect that someone sprayed something in the lock at one point and it penetrated down into the switch...

Also note that there is no "S" pin in the original, I guess the new ones are universal and this might be a contact for a different version/car?



So put the new switch in and hooked it up, put the key in and turned it....

No vroom... (IMG:style_emoticons/default/confused24.gif) Same symptoms as before. So the problem lies elsewhere.

I know that a hotwire directly from the solenoid to the battery works, so the solenoid and starter appear to be OK. As far as I can tell from the wiring diagram, the yellow wire from the switch goes to the relay panel in the engine compartment where there is a connector, and from there to the solenoid via another connector. Maybe bad contacts there preventing the solenoid from getting enough amps to pull? I don't see a fuse that might have blown.



Don't know what else to look at right now....

[tomeric914]

I spoke to George at Auto Atlanta to complain about it and I mentioned how many I've seen on this forum and others all having the same problem. He told me he rarely sees any come back...

There are reasons many of us don't go back to AA.

About 10 years ago, my switch failed. I was on a business trip in Atlanta and stopped by AA to pick up a switch. Spoke to their parts guy who said that the trick was to shim the switch with a small piece of paper. Paid $30

Flew home and installed the switch and it didn't work.

Ordered a new switch off evilBay for $3 plus $6 shipping. When it arrived, I found that it was the identical switch in an identical marked box as the AA switch. Installed that switch and it didn't work either.

Final solution was to purchase a used original German switch from a VW Bug off evilBay for $10. That switch has been in place with no issues for the last 10+ years.

My original switch was cracked and worn and just not making contact.

For those that have melted switches, one thing that hasn't been mentioned is what happens under continuous cranking, when the engine won't start. While the amp draw may by ~25 amps on a fully charged battery, keep in mind that the amps will go up as the volts go down.

[Olympic 914]

About 10 years ago, my switch failed. I was on a business trip in Atlanta and stopped by AA to pick up a switch. Spoke to their parts guy who said that the trick was to shim the switch with a small piece of paper.

Flew home and installed the switch and it didn't work.

Somewhere else I saw a post about shimming the switch with a piece of paper, I can't find that now.
I just replaced my switch with a OEM Porsche switch, made in Germany. And sometimes it will only crank for a second then quit. Turn it off and on again and will crank longer.
Might try this shim thing.
My old original switch wouldn't do this.

[Superhawk996]

For those that have melted switches, one thing that hasn't been mentioned is what happens under continuous cranking, when the engine won't start. While the amp draw may by ~25 amps on a fully charged battery, keep in mind that the amps will go up as the volts go down.

This isn’t the case.

@tomeric914 this response isn’t directed at you personally. I mean no offense.

These sorts of misunderstandings about automotive electrical components and wiring are extremely common. This misunderstanding of electricity is a large portion of why these ignition switches get blamed for problems when the problem in fact lies elsewhere.

Ohms law applies: current draw = voltage divided by resistance (I=V/R). If the supply voltage drops . . . current drops. The solenoid is basically a fixed DC resistance and remains constant.

Melting is a function of increased resistance. Usually from corrosion or loose connections that leads to excessive power (ie heat) being created at the switch contacts, the spade wiring connection to the switch, or within the yellow solenoid wiring itself.

Power = current squared times resistance (P=I^2 * R). In this case, where normal current draw is about 25 amps, it only takes a tiny increase in resistance across a set of electrical contacts or within wiring to generate lots of heat.

Example: let’s say a bit of corrosion builds up and increases the resistance by a minuscule 0.05 ohms which you can’t even measure with a regular multi-meter.

Power = 25*25*0.05 =31.25 watts of heat. How much heat is 31 watts? As a reference, a pencil soldiering iron is typically 25 - 40 watts and will burn you in an instant if you touch the tip and will melt plastics with no problem.

[chmillman]

So, since I had everything mostly apart anyway, just to double check I pulled out the new Porsche-supplied switch and put in the Partworks supplied one. No difference, I was already pretty sure. Odds of having two defective new switches, well, from reading above, I guess it’s possible. However, on the workbench, I was able to insert the key and turn it with an ohmmeter connected to 50 and 15 - contact was made. I even tried it with the old, original cracked switch and it actually still worked. So the switch is most likely not the problem.

I also checked the connectors on the relay board and they look good and uncorroded. So the problem may be at the solenoid/starter connection, tomorrow I will lift the car and start checking underneath. Wondering if I shouldn’t wire a relay from battery + directly to the solenoid, that is actuated by the wire from the starter switch in the cockpit, rather than having the relay in the cockpit near the ignition switch…

[Superhawk996]

Wondering if I shouldn’t wire a relay from battery + directly to the solenoid, that is actuated by the wire from the starter switch in the cockpit, rather than having the relay in the cockpit near the ignition switch…

Your problem and symptoms are indicating you have problems with excessive voltage drop(s) somewhere. Could be in the yellow solenoid wire, the engine to transmission ground strap, or battery cables.

You need to measure voltage drops. Multimeter cannot directly measure resistance accurately enough.

The how to is beyond the scope of this thread. Let me find you a link.
https://www.fenderbender.com/running-a-shop...ircuits-part-11

If you need more assistance - suggest you start a separate thread specific to you car and we can go into detail and work though specific tests if necessary.

BTW - great posts here on the differences between the switches (IMG:style_emoticons/default/smilie_pokal.gif)

[chmillman]

Your problem and symptoms are indicating you have problems with excessive voltage drop(s) somewhere. Could be in the yellow solenoid wire, the engine to transmission ground strap, or battery cables.

Yep - and I am pretty sure it is the yellow wire somewhere along its long and winding road to the engine compartment. To and from I guess, because the battery voltage/current has to come up front from the engine compartment to the switch via the red wire connected to terminal 30 and thense back out to the starter via the yellow wire.

This because of two things - 1, the starter cranks like crazy if I hotwire from the battery+ to the terminal on the solenoid, and 2, we just cleaned all the anchor points and replaced all the ground cables including the engine-trans strap - plus added a couple of additional ground cables to the motor and also redid the + side cables from the battery. I'll post a couple of pictures tomorrow.

[Dave_Darling]

Your car is a 74, I see. I didn't read through the thread, but have you bypassed The Dreaded Seatbelt Interlock Relay ™? That will cause a no-crank when it fails...

--DD

[tomeric914]

@tomeric914 this response isn’t directed at you personally. I mean no offense.

None taken! That was bad on my part. Where my thought (and likely others go) is from power transmission, where a smaller wire at higher voltage can support more power where P=I*V. You are 100% correct that I=V/R where amperage will reduce proportionate to the voltage as long as resistance remains the same. One could argue that resistance can increase as the temperature of the components increases, but that isn't where I was going. Thank you for the correction.

[Superhawk996]

@tomeric914 this response isn’t directed at you personally. I mean no offense.

None taken! That was bad on my part. Where my thought (and likely others go) is from power transmission, where a smaller wire at higher voltage can support more power where P=I*V.

(IMG:style_emoticons/default/beerchug.gif) it was a good discussion to have. And you’re correct that certain loads like an AC induction motor can be approximated as a constant power load. Just not applicable to automotive (at least of our 914’s vintage).

[Superhawk996]

Your car is a 74, I see. I didn't read through the thread, but have you bypassed The Dreaded Seatbelt Interlock Relay ™? That will cause a no-crank when it fails...

--DD

Good catch - didn’t notice his car is a 74’ especially since schematic clip was for an early car. (IMG:style_emoticons/default/smilie_pokal.gif)

Good first check for a late car.

[chmillman]

IT'S FIXED...

OK, you guys are going to have a good laugh, but here goes...

So after trying various things via the cockpit including trying both new switches etc; checking the terminals on the relay panel in the engine compartment, I finally decided to see what kind of voltage I was getting from the yellow wire actually at the solenoid... So I lifted the car. Here is what I found:



(IMG:style_emoticons/default/lol-2.gif)

The backstory is this - a couple of weeks ago on a Friday afternoon I went to pick up the car at my friend the FI specialist - which is almost two hours from here. I already had experienced already occasional problems with the ignition switch, sometimes it took two or three key turns to get the starter to run. But figured this was something to be looked into later. I was able to start the car and back out of his shop, I drove a block to a gas station to grab a snack for the two hour drive home. Back to the car, key in the ignition, no start. Many, many tries, no dice. Finally i called him - he was still in the shop. He came up in his car and tried to get it started, no dice. Went back to his shop and got a few tools and was able to temporarily hotwire the starter, we drove it back to the shop.

It being late and not having a replacement ignition switch anyway he installed a fat red wire from the solenoid to the engine compartment and said, just touch the wire to the battery + and the starter will run, so you can get home. But I didn't see HOW he had installed the red wire. I assumed he had installed in parallel with the yellow wire. However, as you see above, he actually disconnected it. So of course, even after having changed out the ignition switch - twice - it would not start... (IMG:style_emoticons/default/headbang.gif)

I really should have looked underneath first. This is what happens when you assume things.

I didn't like the way the original connector looked so I made a temporary splice. Didn't have any 4mm2 wire either nor a good sized insulated terminal, so I used 2x 2.5mm2 and soldered it to an uninsulated one for the time being.




Lowered the car, got in turned the key and... VROOM! (IMG:style_emoticons/default/driving.gif)

[Superhawk996]

Glad you’re back (IMG:style_emoticons/default/driving.gif) (IMG:style_emoticons/default/piratenanner.gif)

[StarBear]

Lesson learned and noted. Thanks!!

[JamesJ]

So has it been determined that the $50 Porsche ignition switch is no better than other vendors' switches? (Vemo, Beck Arnley, Febi Bilstein, etc...)