Last night my wife started the car with a cold engine, drove 2 miles, parked for 15 minutes and when driving away, the engine shut off. The starter motor turns it over at high speed, but there's no response. External electrical all works, however, I did not check spark at a plug. Vehicle had its 60,000 mile service. The only error readings in the dash have been there for several days, one being that it will be due due for a Service A in 300 miles, and the other being that there is a "lamp malfunction," which is the left front parking lamp that I'm about to replace, but just haven't bought. It has 1/4 tank of fuel, and a good 100 miles + to go on the tank. I noticed my wife had her purse jammed beneath the rear of the driver's seat, and don't know whether there are any computer hook-ups there. Also wondering whether it might have a fuel filter problem, but don't know where it is.

It's stuck in a location where it has to be moved, and I hate to have it towed.
It is new to me, and I have not gotten into the mechanical issues, other than to do oil and filter changes at 4500 mile intervals.

Any suggestions?

If this is the wrong forum, let me know.

Perhaps this is a K-40 problem. Yours is eight years old. Sometimes a K-40 failure will throw an unrelated code, and sometimes no codes are added.

As for how to tell, it's by examination of the insides of yours or substitution of a known-good module. It's in the module box under the hood.

Matt:

Thanks very much. I've got no background in electronics, just the old fashioned mechanics, so if you have time to respond further, my first questions are:

1. What does the K-40 controls?

2. Is it identified by this particular name when I look there?

3. Does it just fail by itself, so that the fix is a simple unplug and replacement?

Chris

The K-40 supplies power to the injection computer and the combination control module. Probably other things. It replaces the prior OVP (but the actual OVP circuitry is moved to the computer).

It's at the very front of the module box, and has a few fuses on top. You should check those fuses first, of course. There is a M-B part number on it, but it doesn't say K-40.

The K-40 most definitely fails by itself with alarming regularity on these cars. If it's bad, it is a as simple as plugging a new one in. It has a number of electrical connectors, but they're all different so you can't get them in the wrong place.

If you remove the module, it is possible to remove its cover and inspect the solder joints. This is what fails. If you do this, you'll want a strong lamp and perhaps a magnifying glass. Look for very small cracks in the solder joints.

Almost sounds like a crank position sensor failure.

Try the search function for "crank position sensor" or "cps". There's a lot of info to read.

Very very very common failure on M112 and M113 V6 and V8 engines.

If you know where it's located it takes about 5-10 minutes to replace. It's impossible to see. You have to reach down between the engine and firewall to replace it.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Matt & Paul:

Thank you both very much for the most helpful suggestions, which I will follow.

Chris

When the K-40 fails while driving, it is because the circuit is interrupted due to expansion of the parts under temperature. It would probably start when allowed to cool, and cause very intermittent and seemingly unrelated problems.

Suginami probably has the problem nailed. I don't think about the CPS since my car lacks that. Neither is an expensive part, IIRC, but both will leave you stranded.

Matt & Paul:

Thanks again. Another interesting observation is that, after sitting for 24 hours, it started right up and went fine for 10 miles on the freeway, till I had to stop at a stop light and, then shut down and would not start. Fortunately, I was able to push and coast it to a better location til tomorrow. Not sure whether this affects the diagnosis.

Yep, I bet you $100 it's your crank position sensor.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Matt & Paul:

You guys were right on the money here! It was the crank position sensor. I'm embarrassed to say I had my local independent put it in, due to time problems and needing it back on the road today. With your help, however, I was able to let him know I already knew the likely diagnosis and that it should be an easy fix. Thanks very much.

Chris

I have a similar intermittent starting problem with my car, which hasn't been resolved after spending hundred of dollars at the dealership.

I would like to replace the CPS myself, just to see if that will take care of the problem, because it seems like an easy an inexpensive thing to do (even though my problem occurs hot or cold, and from what I've read, failure of the CPS only affect hot starts).

I would like to know the following:

- Can the crank position sensor be tested to see whether or not it's defective, once removed (ohm test or something like that).

- Is there a link that shows where this sensor is located on a W210 E320, and what it looks like (if such a link doesn't exist, I'd appreciate it if somebody can post a clear picture of the part and its location here).

Thanks.

The cps is located in the gap between the engine and the firewall. It is impossible to see, and you find it by touch. If you know where it is, it can be removed in 2-3 minutes.

To test for a defective cps, heat it up with a heat gun or hair dryer, when hooked up to a volt meter, if you get an open circuit, then it is bad.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".