out of blue, E300D wont start

[Pweber]

Been running perfect. No reason to have an issue nor has anything changed or repairs done, etc. Just got in it to move the car and noticed when I crank the car the red/ yellow lamps on the mirror flash alternate while cranking. Glow plug light comes on as normal but it is as if any ability to run is disable. No stumble or fire at all. Just cranks. Does this flashing red/ green while cranking indicate something?

[TMAllison]

With the hood up and door open, do you hear the *click* of the shutoff valve opening when the key hits pos #2?

[Matt L]

"when I crank the car the red/ yellow lamps on the mirror flash alternate while cranking"

That says it all. DAS is locking you out.

Try locking and unlocking the car from the outside or with the remote. Otherwise I would recommend checking the K40 relay module.

[Pweber]

For no good reason and nothing changing the car fired right up this morning. No idea why it did that. Does the key mate to the car and could that be getting bad? If so, I assume I should try the other key if it happens agian?

[Matt L]

Are you on your original K40 relay module?

[nate300d]

Originally Posted by Matt L

That says it all. DAS is locking you out.

What is DAS?

[Matt L]

Drive Authorization System. I believe that K40 problems can trigger this by not supplying power to the computer, while the RCL has power. When the RCL tries to verify the computer in the car, it gets no response.

DAS will also lock out the car if you lock from the outside and unlock from the inside. When this happens, the starter motor will function but no fuel will be injected, along with alternating lamps on the interior mirror. I don't know how the later cars (which lack these lamps) tell you that DAS is locking you out.

[Pweber]

I would assume it is the original K40 relay. Where is it and should I/ be prudent to get a spare given this event?

[TMAllison]

It is in the right (passenger) side box. The front most unit. Takes longer to R & R the cover than to replace it.

After 11 years is prob prudent to replace it. Is ~$80 at dealer rates.

Causes numerous intermittent electrical faults. As Matt has said, may be responsible for DAS recognition fault; is also responsible for powering up the shutoff valve after start is authorized, among other things.

[aklim]

Have you tried it with another key? Sometimes the key may be screwy

[Pweber]

Does the gas car have a k40 relay? If so could I swap out my 1999 e320 k40 in the event this happens again?

[aklim]

IIRC, it does. Why not switch it? That way if the E320 develops a problem and the E300 is fixed you know what the problem is.

[Matt L]

Be sure to check the part numbers before switching them.

[nhdoc]

Both cars have K40 relays but I am pretty sure they are NOT interchangeable. I know the gasser K40 includes a fuel pump relay which diesels do not...as you were warned, make sure the PN is identical if you do try and swap them, I think you will find they are not.

[Jeremy5848]

Originally Posted by TMAllison

With the hood up and door open, do you hear the *click* of the shutoff valve opening when the key hits pos #2?

My new car (1996 E300D) didn't want to start this morning. It was in the warm garage (about 60F) and unlocked. When I turned the key to position 1, I got the ABS light; position 2, I didn't see any of the additional lights, and the ABS light turned off as it is programmed to do.

I thought it was strange that there were no idiot lights but I'm new to this car and I thought that the glowplug light might have cycled off while I was putting on my seatbelt. So I turned the key through to position 3 and the engine cranked but did not fire. After 5 seconds of this I stopped, cycled the key, tried again, no joy. Several more attempts without success.

During one or more of the starting attempts I noticed that the "fasten seat belt" warning that the instrument cluster displays in place of the odometer/clock/outside temp was flickering and obviously in pain. No other idiot lights, no CEL. No flashing red/green lights on the mirror.

I lifted the hood, looked for obvious problems. Nothing found. Tried again. Eventually, on one of the tries, there was a 'click' from under the hood in key position 2, the idiot lights came on, the glow plug light cycled and I was able to start the engine.

This happened once again after I stopped at my mechanic to discuss another car (the W123 car has an a/c leak). Easier starting this time after two attempts, same symptoms. Rest of the day, many stops and starts, no problems starting.

Couple of instances when it acted (at low speeds, engine near idle while starting from a stop or rounding a corner) like it was going to stall, but recovered. Reminded me a lot of a carburetted gasser flooding due to fuel slop from the float chamber -- a hesitation sort of thing. Never actually stalled.

Since this is to be my wife's daily driver, I'd really prefer it to be reliable. I've read in some of the posts here and elsewhere about the K40 relay (whatever it is) and then this mention of the fuel cutoff. Since the idiot lights don't work, I suspect more than the fuel shutoff valve. There's no indication in the PO's extensive collection of service records of the K40 relay having ever been replaced.

Should I wait until it won't start at all? Replace K40 on general principles? Are there other symptoms to watch for?

Jeremy