Weather here has been in the 40s to mid 50sso i have been driving the car more lately and i noticed an issue. If i turn the key to glow plug on and then to crank it crank before the glow plug light is off it will crank every time. If i wait to turn the key once the light is off, i might have to cycle the key 2 or 3 times before it will crank. So i dont know if this is a sign of the glow plug relay failing or another part of the start circuit going bad? Or is this normal based on my outside temp?

Pulled the k40 block and reheated most of the larger solder joints. Seemed to take care of my issue for now.

I had a starting problem with my 99 E300D. When I would turn the key to position 1 or 2 everything was normal. Then after the glow plug light went out I would turn the key to start the car and nothing would happen.

I'm not sure if your problem is the same.

The problem I had was with the ignition switch. I needed to have the dealer replace it so they could program the switch to my car and key. I have not had a problem since and its been at least 5 years ago.

Can you share what the dealer charged for this repair? Just curious for comparison for when I take mine in.

I have the exact same symptom on my '98. It's intermittent and happens maybe every 3rd or 4th time I drive the car. After glow plug light goes out, turn key to start and -nothing-. Take key out, re-insert, try again, fires right up.

I thought the electrical portion of the ignition switch would be easy to replace and not require a dealer trip, no? I was planning to buy this part, but I didn't think it required any re-coding? Sounds like I should let the dealer sort this one out.
https://www.pelicanparts.com/catalog/SuperCat/3742/MBZ_3742_ELIGNT_pg2.htm

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1998 E300 turbodiesel

America's Rights and Freedoms Are Not The Enemy!

Yeah that was the symptom I was getting but if during light on glow plug cycle I turn to crank it would start. If I went to crank after the light went out I would get nothing. Also question for you, can you remove your key with gear shifter in neutral?

I was able to dig up some info on my problem, it was December 2010. I don't have the cost but it was definitely under $1000 for the switch and labor. I'm sure it's something you could call and get a price from the dealer.



Here is a note I found from an email describing my problem:
When the car does not start there is no ground coming out of pin 17 from the ECM (N3/7). It is very easy the check this. Put an ohm meter on pin 2, connector I on the K40/4 relay. This ground excites the coil of relay k2 on the K40/4 relay. This relay controls the starter. When the car does start there is a ground coming out of pin 17 from the ECM closing the k2 relay, powering the starter.

If you perform this check and have the same results I would replace the ignition switch.


Another note I found was trying a different key. By any chance did you try a different key?

This morning i tried the cold start and it was fine with both keys since i reflowed solder. I did notice one key seems to have a better fit than the other. I'm going to order a new key shell off ebay and swap the guts.

Didn't want to start a new thread, so I'm adding to this one. My 96 E300 developed a "no start" issue after sitting for a couple of weeks. After the plugs were glowed, turning the key would spin the starter but the car wouldn't start. Then I noticed the red light in the rear view mirror. (NOT GREEN AND RED ALTERNATING). I researched everywhere I could think of and saw nothing about a flashing red LED without the green one flashing. At any rate, it seems that flashing of these lights is related to the immobilizer and the K40 relay.

I saw several posts and watched videos on youtube about the bad solder joints in the K40, so I pulled it and re-soldered most of the connections. When I re-installed the K40, the car did start after plugs were glowed, but then threw "ETS" and "ABS" warnings and after a few minutes it quit running too. So, I ordered a new K40 relay online for $110, hooked it up and we are all systems go again. I honestly think that we should start of list of parts to "Just replace it" so you don't get stranded somewhere in the future- starting with fuel lines, then the K40, etc...