1998 E300 DT Intermittent No-Start...Help!

[nhdoc]

Hi,

Is anyone familiar with the starter circuitry in the 606 turbo? I have an intermittent no-start condition which happens after I preglow the engine and turn the key to start - then nothing happens, no click, nothing. I am guessing could be one of the following:

1) Starter Solenoid (I have check the battery and wiring to the solenoid and connections and they are fine).

2) Key Switch

3) Neutral Safety Switch (which I have seen is a reed switch activated by magnet in the 722.6 tranny).

4) Starter Controller relay??? There must be a relay which engages and disengages the starter solenoid when the key is switched to the start position since the starter on these cars remains engaged until the engine starts.

I am inclined to believe it is 2,3 or 4 (I don't know where 4 is of if it is part of the overall "brain" of the car or not).

Can anybody shed any light on this? Of course if it were not intermittent it would be a snap to trace it but if it happens and I remove the key and try again it will usually start on the second or third try and then all is well again and it may not happen again for 30 more starts.

[Jay Gibbs]

I have the same problem every now and again...very infrequent. I think it has something to do with the car's security system- the computerized electronic key and the car computer recognizing the key. 9 times out of 10 if I turn off the key, remove it from the ignition, then reinsert it, it starts fine the second time. Always 100% by the third try. I wouldn't waste your time or money trying to track this down unless this happens on a VERY regular- even daily basis.

J.G.

[deltajetfixer]

Hi Marty,

Have you checked the condition of your keyfob's battery?

Are its contacts clean?

[nhdoc]

I hadn't really considered the key because the car pre-heats like normal....would the computer allow the car to pre-heat if it didn't recognize the key?

The batteries in my key are only a few months old, but I have another key I can try and see if it does it with that one too...thanks for the tip.

[jcyuhn]

My 98 E300 did this once in while as well. Same routine - the car preglows, the accessories come on, but no cranky on the starty. Pulling the key and trying again always did the trick.

Changing the battery won't help. The battery only powers the remote locking/unlocking functions. Starting the car is a separate thing. Gilly, I think, has posted some discussions on how the electronic key operates.

- JimY

[suginami]

I agree with the suggestion that your key is worn out.

This problem is not exclusive to diesel models, affecting all 1998 and newer models with the electronic key.

It happened to my mother's '99 E430, and the local Mercedes independent, MB Stars, explained that it is not an unusual problem.

When you insert the key, the car might not recognize that it is the key programmed for your car, so nothing happens.

If you have a second key, try it, and see if the problem goes away. It worked on my mother's car.

[nhdoc]

I also noticed that the red lens on the front of the key I was using was extremely scratched up so I polished it out a bit using some Novus plastic polish and removed about 75% of the scratches...it's an original 1998 key so maybe there were enough scratches on it to prevent it from reading right.

I'll report back if this improves the situation any.

[aklim]

I am not sure what it is but I have an idea what it is not. It is not the battery in the key. The wife just got back and I took the entire battery out of the key. There are 2 button cells there and I took them and the panic button area out. Guess what, the car started. That confirms that there is a transponder that gets a signal from the ignition switch and it sends back a signal to the ignition switch that reports some sort of access code.

[turbodiesel]

Good luck! These 210 cars are too damn complicated!

[aklim]

Originally Posted by nhdoc

I also noticed that the red lens on the front of the key I was using was extremely scratched up so I polished it out a bit using some Novus plastic polish and removed about 75% of the scratches...it's an original 1998 key so maybe there were enough scratches on it to prevent it from reading right.

I'll report back if this improves the situation any.

One of my keys is pretty scratched up on the lens area too. I believe that is the lens for the summer thingy where you can point it at the driver door and hold down the unlock button and it opens the sunroof and rolls down the windows. If you do the same except hold down the lock button it will close the sunroof and roll up the windows.

Experiment #2. I covered up the red lens and attemped to start the car. The key fit in but the usual "click" wasn't heard. Also, the key would not turn. Therefore, I am highly doubtful that was the issue.

[nhdoc]

The "no crank" problem occurred today again and several times. One time it took about 5 tries before it started and I really began to panic. Well, when I got home I removed the cover from the electronics compartment located under the hood near the firewall on the passenger side and pulled a relay from the front fuse panel which then prevented the starter from engaging just like I had been experiencing in my "no crank" condition.

I replaced it and found the car was then exhibiting the "no crank" condition still so I tapped it with a screwdriver and then the car started. As a second test I pulled the cover from the relay and plugged it into the socket and put the key to "1" and when I manually pushed the contacts together the starter would crank but not start unless the key was in the "2" position and it will crank for as long as the relay is held closed, even after the car has started.

So this relay definitely has complete control over the starter motor. My dealer had the relay in stock for $31 so I swung by and picked up a new one and installed it. The car seems to be OK now so, if I am very lucky this was the cuplrit. FYI the PN is A 002 542 13 19.

UPDATE: It is now several weeks later and the problem has not occurred again, so I conclude that this relay was definitely the part that was faulty. If anyone is having this problem don't wait until it finally fails and leaves you stranded...at least pick one up and keep it in the glove compartment so you can install it when you need to. All you need is a screwdriver to take the cover off the compartment under the hood and it will take less than 5 minutes to replace it.