electrical and ignition Ignition Switch Short

[landon]

My engine would not shut off today after turning the key off. After switching the key to different positions a few times it finally sputtered to a halt. Later shutoffs were normal although at one point it acted like it wanted to stay running and then shut down. Switch operation for starting is normal. I had the switch out last year for lubrication and I am thinking it is developing a short. Any suggested fixes? Or just buy a new switch?  

[Simeon]

Just checking: this isn't 'run on' as in where the engine is self firing after the ignition is turned off?

 

check the wiring at the back of the switch. There are a lot of terminals in a small area and if something has been pulled adrift it could be shorting. 

[Mike Self]

And of course keep in mind that the ignition "switch" is a completely different part from the lock assembly...I agree with Simeon--you may have a cocked or loose "hot all the time" wire on the back side of the ign switch that is touching "hot only with the ignition on" terminal.  

 

mike

[landon]

11 hours ago, Simeon said:

Just checking: this isn't 'run on' as in where the engine is self firing after the ignition is turned off?

 

check the wiring at the back of the switch. There are a lot of terminals in a small area and if something has been pulled adrift it could be shorting. 

No this was definitely not a "run on" condition. The engine did not miss a beat when turning the switch off and on again and it idled strong and normal. A couple of shut downs this morning were normal.

 

I will check wiring at the back of the switch. Can the switches short internally?

[Simeon]

Anything is possible.  The actual electrical part of the switch is fully sealed so apart from not knowing what the internal configuration is like (and therefore the chances of an internal short) it is also unlikely that any kind of damage may have been done to the switch itself. 

 

If if you want to rule it out you can disconnect the wiring and test with a multimeter (this will also check the wiring). 

[jgerock]

AND - new switches (the electrical part) can be faulty right from the supplier. BTDT

[mike472]

Are these switches available new?  In Jim’s last post he alluded to the fact that some new ones were bad right from he supplier.  I’m pretty sure the one in my blue car is fried. No switched B+ at my megasquirt relay board.  It’s been stranding me once in a while and with a few on and off movements I was able to resuscitate it. It has entered complete failure mode. Putting a meter on it today

[2002iii]

5 hours ago, mike472 said:

Are these switches available new?  In Jim’s last post he alluded to the fact that some new ones were bad right from he supplier.  I’m pretty sure the one in my blue car is fried. No switched B+ at my megasquirt relay board.  It’s been stranding me once in a while and with a few on and off movements I was able to resuscitate it. It has entered complete failure mode. Putting a meter on it today

Unfortunately hese switches have been NLA for a while now and if you can find a new one they go for about $275.

 

What usually happens is the small detent ball that keeps the ignition in position breaks loose and causes an intermittent short as it moves around inside the switch. The plastic used in these switches is very brittle and breaks apart due to age and heat cycling.

 

I took apart a couple broken ones and have been thinking about seeing if new plastic pieces could be 3D printed out of better plastic.

 

I had one that started smoking when the detent ball shorted the switch, luckily I had a battery kill switch.

[John76]

Here's a snap of the innards.

 

The detent ball spring was weak on mine, causing poor connections between the contacts and rotor disc.

Thankfully, no smoke or sparks.

I will gladly send someone the parts to be 3D printed...just send me a PM.

 

John

 

 

[2002iii]

1 hour ago, John76 said:

Here's a snap of the innards.

 

The detent ball spring was weak on mine, causing poor connections between the contacts and rotor disc.

Thankfully, no smoke or sparks.

I will gladly send someone the parts to be 3D printed...just send me a PM.

 

John

 

 

That spring looks short compared to the ones I've taken apart, it looks like it broke.

 

All the ones I took apart the plastic rotors had broken. One broke around the detent ball hole allowing the ball to move around inside and short the contacts causing the smoke mentioned above.

 

Another broke where the lock part engages the plastic rotor.

 

The third broke the spindle part of the rotor that sits in the spring in the middle.

[mike472]

Thanks guys. I’m going to take mine apart and see if I can fix it. Depending on what’s wrong it might be fairly easy to fix. 

[landon]

So, I started this post in 2016 and had what seemed to be an intermittent short in the ignition switch.

The issue "mostly" went away for some years but returned with more consistency last year. I did start the car today and the old switch operated normally.

 

I got around to replacing the electrical switch today. Checked wire connections to ensure everything is the right place. Looks good. All wire connectors look good.

 

Startup is normal. When I turn the key from "fahrt" to the "o" accessory position the engine stays running. The "L" light comes on as well as the brake light. When I turn the key to "Halt" it shuts off. Went thru this several times and it consistently does the same thing.

 

What do I  check now? 

 TIA for any ideas...  

[2002iii]

6 hours ago, landon said:

So, I started this post in 2016 and had what seemed to be an intermittent short in the ignition switch.

The issue "mostly" went away for some years but returned with more consistency last year. I did start the car today and the old switch operated normally.

 

I got around to replacing the electrical switch today. Checked wire connections to ensure everything is the right place. Looks good. All wire connectors look good.

 

Startup is normal. When I turn the key from "fahrt" to the "o" accessory position the engine stays running. The "L" light comes on as well as the brake light. When I turn the key to "Halt" it shuts off. Went thru this several times and it consistently does the same thing.

 

What do I  check now? 

 TIA for any ideas...  

With the engine running in the accessory position check the coil for power, it shouldn't have any.

 

Sounds like wiring problems, maybe some of the green wires are mixed up on the switch. Or someone has messed with the wiring and/or a short circuit.

[landon]

55 minutes ago, 2002iii said:

With the engine running in the accessory position check the coil for power, it shouldn't have any.

 

Sounds like wiring problems, maybe some of the green wires are mixed up on the switch. Or someone has messed with the wiring and/or a short circuit.

Ok, it seems the coil does have power on accessory because the engine is purring along and nicely idling. 

Coil gets power from #12 fuse -correct? And that connects back to ignition switch via #4 fuse.

I saw John76's switch diagram and see the green wires should not have voltage on accessory. I briefly checked that today and saw no voltage at the green wires in any key position. I'll double check that and all the wire connections at the switch...

[mike472]

I think it’s your ignition switch. If it came apart inside you could have shorted the hot lead onto that accessory terminal. I just bought a spare on eBay. They break in different ways with brittle plastic being the culprit most of the time. That switch feeds the fuse block which  in turn feeds your coil.  If everything was good before and this suddenly came from out of nowhere I would bet on it. There is another switch for sale on eBay now for about $60