Starter engages immediately on turning key
 

The engine starts as soon as I turn the key to the FIRST click, and not yet to the normal start position, although I can turn it to there as normal and the starter doesn't disengage after letting the key return to the normal "on" position.

At this point I can drive the car, forward or reverse without apparent problems other than the sound of the starter motor running and a nasty sound as I move between reverse and drive...this seems to come from the area of the starter motor, which I must presume is because the pinion gear is stuck in the "start" or extended position.

If I back it off just a bit the power shuts off to the whole car, which is what I would expect.

The car is a 190E, 2.6, 1990.

Any ideas? First and easiest place to check?

This will be a wild guess, as i have absolutely no preferences..

Your ignition tumbler could somehow be shorting the power to the starter when in 1'st position.
I have seen a thread about pulling the tumbler out for inspection/replacement somewhere on the forum.. Try a search.

I assume this problem has developed recently? (not a car you just bought with the defect already there)

Freestyler

Thanks for the suggestion.

Yes it is a car I have had for many years.

I had just come back from a long trip about 800 miles round trip. (No problems during trip except for the cost of gas going up nearly 15c from start to finish!)

About an hour later, I took it out again to go get groceries, it started with no problem, back when we started the car at the store, it made a funny sound as the gear shifted from Reverse to Drive...made me stop and listen and this is when I noticed it.



//don

I suspect a bad ignition switch..
 

I'd bet on a bad ignition switch. #1, don't run it again with the starter engaging, busted teeth on a ring gear would be no fun.

A worn cam or stuck contacts inside the ignition switch would cause the starter to stick 'on'. I browsed your earlier posts and noticed the random stall. Since the stalling seems to be somewhat associated with the steering wheel that further implicates the ignition switch.

Since I made a post a while back about the ignition switch on my 560sl I had several requests for the removal procedure. It's on the net here It applies to the 560 but our cars use the same switch so most should apply.

If you decide to pull the switch... the connector pins are numbered. Pins 30 and P30 are power input, pin 50 goes to the starter. This circuit should be open in all positions except 'Start'

You could test the starter solenoid by disconnecting the cable between the solenoid and the starter motor itself then trigger the solenoid and listen for it to snap in and out. Depending on the access to the starter that may be difficult.

As a follow up to this, I have finally found some time to experiment:

I have found that the ignition switch is not the culprit. I initially found the cables plugged into the ignition switch needed reseating as they had crept out a fraction.

Upon trying the ignition everything worked as it seemed it should ... so I put everything back in place and used it for a week or so.

A few days later I noticed that there was an odd sound beginning to reoccur after starting, almost as if 2 plates were just touching as they rotated.

This sometimes became more evident when moving from Park through reverse, neutral and into drive and then back to park.

In particular, it would happen if I engaged either Reverse moved the car a foot or so, then into drive to return back to the same spot. Conversely it would do the same when I first went to drive and then to reverse.

Shortly after noticing this, the ignition auto start problem reoccurred.

To get the instrument panel out on this model you have to disconnect the speedo cable AT the Transmission.

The next experiment was to just disconnect the speedo cable at the transmission and everything returned to normal!

There is an electrical connector on the left side of the transmission right at the point where the speedo cable goes up into the tranny.

It has 4 connectors, is about 2 inches long, about 3/8 in wide. Could this be the electrical connector that is causing the issues?

What is this connector? There is a smaller cable harness leading from it going back a little. I am not sure where this leads as it goes over or into a plate that is about 6 - 8 inches behind the tranny. ... Maybe the catalytic or oxygen sensor (??)

Anyway, I would appreciate any further assistance or advice. (I also have to wonder if this is the source of the car cutting out over the last year going around corners? i.e./.: a chaffed wire shorting or broken cable/connector? ... although everything looks like it is OK)