Calling all ign. switch gurus (interesting mech. question)

[Lilleyvanilli]

I'm curious if anyone can put words what actually happens mechanically within the ign. switch assembly when you turn your key. My car is a '76, so not sure if the switch differs from year to year.

I'm particularly interested in the function of the tiny ball bearing looking thingie (feels spring loaded?) on the backside of the switch. Does something contact this thing and complete a circuit? On both my old and new switch, it looks as if sometimes it gets lodged a bit and I wind up taking the switch out and 'popping' it back into place a tad. I thought this was my intermittent starting issue because it seemed to start one time, but not anymore, even with new switch

Another funny thing... The way I had been starting the car was to turn key and crank, then let fingers off the key while goosing the throttle once and it jumps to life ( but not while you are applying clockwise pressure to the key as you would normally. weird.) Well that does not work anymore. Just won't start now. Nice new switch worked great for about 4 days. Nice new coil too.

[Mike Self]

The ignition switch actually has two parts: the lock assembly (into which you insert your key) and the electrical switch itself (the bakelite piece on the back that has wires attached to it).

The little balls inside the switch shouldn't be falling out. They are what holds the switch in the proper position when you turn the key and are pressed into position inside the switch assembly.

The action that causes the key to spring back into the "run" position from "start) is inside the electrical switch, so if yours isn't doing that, there's something wrong with the switch. The lock assembly has a little part inside that keeps you from turning the key to start more than once without turning it back to off; it can break and prevent the key from turning to the start position. If this has happened--I did a column on how to dismantle the lock assembly and repair/remove the offending "anti-repeat" part.

cheers

mike

[Lilleyvanilli]

Hi Mike,

I'd be interested in your piece you wrote on the rebuild. I am going out right now to try your other trouble shooting method (you replied to a dif. post with some good common sense stuff. Thx!)

Just to clarify, my 'spring-y ball bearing' is not falling out and mechanically, all FEELS like it always has when I turn the key. On both of my switches, old and new, there is only one visible ball bearing that is seen from the outside of the back of the switch, like it sits comfortably in it's own hole that is punched in the metal casing of the switch. It's the only one and the old switch had a tiny bit of grease on it, so I followed suit on the new.

But sometimes, it seems like it's rotated itself under the switch casing/out of the hole off to one side (like it's partially compressed). It's ever so slight, but even when I pop it back out/into position (and seriously, you'd never see a diff. unless you viewed switch from the side), car still doesn't start. Still kinda curious on what this little dimple actually does. Seems like the only mechanical piece visible on the actual elec. switch.

Another post on a '74 car mentioned a relay or something causing intermittent starting, located beside the ign. switch, but I don't see anything like that on the '76

[Lilleyvanilli]

Just thought of something...

for 15 years, I've been able to start the car and remove the ignition key in the on position. I love it because I can start the car, let her warm up, go move the other car and come back and move the BMW out. Nice, but this is not normal, right? Maybe something now is finally worn out or do all '02's do this? Never thought to ask before.

[Lilleyvanilli]

This just in...

Car now ACTS like it wants to start. Putters immediately, like it's getting a burst of current, but just turns over from that point. AND... when I go to turn key to 'off' position, it very (very) briefly putters like it wants to start... like it's getting a burst of current upon transitioning from the run position to accessory. This is killing me. Old switch occasionally did the same.

This design seems like such a simple setup. I'm so close, but the issue might be in the actual key barrel? The expensive honker-of-a-die-cast unit? If I bought a new faulty switch, grrrr...

[Mike Self]

The problem is probably not in the lock assembly or its diecast housing; all the lock assy does is rotate a little cross pin that engages a slot on the inside of the electrical switch (the side opposite where the wires connect, where the switch is pressed against the lock). Now if that pin is broken or badly worn, rotating the key from "garage" to auxiliary (radio plays, ign not on) to "fahrt" (run--ign on) to "start", won't move the electrical switch so that the proper wires are electrically connected. So you want to examine the back side of the lock, by removing the switch from the lock. Suggest disconnecting the battery when you do this to prevent shorts. Look at the little pin on the back side of the lock while you rotate the key. If the pin turns with the key and isn't obviously worn or broken, the lock assy is OK.

If that's the case, reconnect the battery, and with the switch assembly still disconnected from the lock and hanging by its wires, use a screwdriver to rotate the switch from aux, to on, to start. If nothing happens, the switch may be the culprit. But just to make sure, run a jumper wire from the switch lead that's hot all the time to the lead that goes to the starter motor (you'll have to check your wiring diagram to see which is which). If the starter now turns over, the switch is the culprit. If not, the fault lies with the wiring, the starter motor or the starter relay.

Lemme know whatcha find.

mike

BTW, a worn switch will allow key removal in the run position; my '69 will do this, but my 73, with more miles on the odometer won't...When new you can't remove the key except in the off and auxiliary position.

[Lilleyvanilli]

Well I just spent damn near an hour with a very detailed post of what I discovered today, complete with wiring dia. info and the damn thing just disappeared!! I've had enough for today. Long story short, it started around 5pm with my screwdriver... and the key... "same as it ever was", but running, until I need to be somewhere important. I'll adjust my attitude and rewrite it all tomorrow.

Where is the starter relay and can I test with multimeter? Volts or ohms? Just to clarify, starter always turns over, just intermittent/no spark at the reg. key position it seems.

[Mike Self]

the ignition)--starter turns over in the start position but sometimes you have no spark--I'd still suspect that ignition switch (the electrical part).

Try this: run a jumper wire between the ign switch wire that's hot all the time, and the wire that supplies current to the coil. Then start the car as normal. If it now functions properly (i.e. the ignition isn't intermittent) then the problem is in the switch. If that doesn't help, then the problem is in the wiring between the switch and the coil, the coil itself, or parts of the secondary ignition circuit (points, condenser, cap, rotor, plugs, plug wires etc).

mike

[Lilleyvanilli]

Well, good news (sorta)

Found my 'hot all the time' (one of the reds, test with volt meter) and bridged with Bl/Wh. starter wire. She started right up. (REMEMBER, this is a NEW $75 ign. switch from BMW. Sound like it's a dud?)

Also tried this at the orange diagnostics plug in eng. bay (connect #1 to #7, or red to bl/wh.) Started right up. (again, Dud Switch?)

I also used a large flat blade screw driver to turn the switch (instead of the key) and she starts right up. (OH, switch must be GOOD, but all in the key barrel/casting looks fine)

I also put it all back together and used the key and she starts right up.

(OH... well here we go again...)

This "I'll start when I want to" issue is truly my nemesis. Going out to see how she 'feels today'....

(at least I have a choice of how I want to start my car now) Which wires do I connect my new STARTER BUTTON to... red and Bl/Wh.?

[Lilleyvanilli]

HA! just when I think all's well... home on a flatbed Sunday morning after stranding me Sat. night before 2 gigs. NOT GOOD.

SO NOW...

Connecting 'hot all the time' to starter wire WILL NOT start car

Connecting pin #7 to #1 WILL NOT start the car (even though I showed a buddy this 30 min. before she stranded me)

Pulling out the switch and turning with a screwdriver WILL NOT start the car.

Turning with the key will not start the car (or produce the weird jolt that usually fires it up when you let go of the key). ???!!!!???

BUT...

I checked with my volt meter that I do have voltage from my ign. switch to the coil when it won't start. I checked/cleaned cap /rotor for corrosion/moisture and no problems (rotor ohmed out around 5 I think).

I am slowly starting to suspect the Crane XR700 elec. ign. is playing naughty (whenever it wants to, mostly when I need to be somewhere).

Can anybody help me determine/check the LED/chopper wheel? What should I look for? Should light be on all the time or just pulse when the slot in the disc comes around, sending spark to the wires?