'99 E300 TD Won't Start - Need Help!!! - PeachParts Mercedes-Benz Forum

MaryA · #1 05-30-2010, 11:10 AM

This is the 2nd time this has happened to us. 1st time was on vacation in Florida last September...around noon we went into a store for about 15 minutes and when we came back out the car wouldn't start. We happened to be at a SAM's Club and their "technician" came out and said it was a battery issue so we ended up buying a new battery. The car still wouldn't start. We called for a cab and went back to the hotel. Later that night around 9 we went back to the car and it started right up...drove straight to the hotel (about a 15 to 20 minute drive), tured the car off and tried to start it again and nothing...wouldn't start. When we got ready to leave the next morning we drove straight home to Atlanta and never shut the car off for fear of not being able to get it started again. My husband replaced the starter and it's been running fine since then.

Yesterday we had to park it in the driveway for about 7 hours and when we went to pull the car into the garage the same thing happened again. The car won't start. When you turn the key all the dash lights come on and the glow plug light cycles, but when you then go to start the car, it doesn't start. We've tried both keys. My husband is completed stumped on this one. We've read many different forums and some point to the security system, some refer to the K40 relay and most to the battery. My husband does not think it's a battery issue.

If you need more information please let me know!!! Any help would be greatly appreciated!!!

TMAllison · #2 05-30-2010, 12:43 PM

Sounds like the K40 relay to me. Causes intermittent electrical failures due to minute cracks in its printed circut board. Sitting and cooling results in contraction allowing the circut to be completed.

Next time it wont start, pop the hood and lower the drivers window. When the key is turned to Pos #2 you should hear the "click" of the shut off valve (black plastic valve) openning on the side of the IP. If it doesnt click open it wont start as the IP receives no fuel. In this senario it is almost always the K40 relay at fault.

MaryA · #3 05-30-2010, 01:10 PM

Had my wife try to start while I had my hand on it...the IP is clicking...but the car still won't start. Visually inspected the K40 and it looks good. The starter is not turning. Is there a relay that controls the starter? Could the K40 stop the starter from turning? I've rebuilt several older mercedes engines so I defnitely know my way around cars...but this is the first '99 I've had.

TMAllison · #4 05-30-2010, 01:41 PM

Does your steering wheel lock retract when the key is first inserted?

Turn key to pos #2, press and hold REST on the CCU controller for 5 secs, use left and right AUTO buttons to toggle to screen #24 and verify your batt voltage. Mine reads about 11.5V with the blower motor off, door open and dash lit up.

MaryA · #5 05-30-2010, 01:48 PM

Thank you so much for responding!!!! Yes the steering wheel lock retracts. Will go out now and see what the battery voltage is.

MaryA · #6 05-30-2010, 01:52 PM

We have 11.6...doors open, lights on and blower off.

TMAllison · #7 05-30-2010, 02:07 PM

Hmmmm...I still come back to the K40 relay. Steering lock retracting is the first part of the security handshake between key and ign. More occurs after that. K40 feeds power to numerous systems.

You def hear the SOV open and then close each time the key is turned back and forth from pos 1 to 2?

Perhaps MattL will chime in with his thoughts.

MaryA · #8 05-30-2010, 02:12 PM

Yes definitely hear the SOV open and close. I really appreciate all your help.

The only good thing is this happened at home and we didn't get stranded somewhere.

JimSmith · #9 05-30-2010, 02:39 PM

I have had this happen a few times as well. Take the car out of park and into neutral and try it, then back to park if it doesn't start and try again. On my car this is a once every 6 months event, and moving the shift lever takes care of it. Make sure you are stepping on the brake pedal as well.

Good luck,

Jim

MaryA · #10 05-30-2010, 02:58 PM

Jim,

Thanks for the input! We tried what you suggested...no luck.

Pavka007 · #11 05-30-2010, 03:09 PM

Quote:

Originally Posted by MaryA

Jim,

Thanks for the input! We tried what you suggested...no luck.

Do you have error codes?

MaryA · #12 05-30-2010, 03:16 PM

Absolutely no error codes...part of the frustration I'm having over this.

Pavka007 · #13 05-30-2010, 03:28 PM

That is strange, No battery, no starter motor, no SOV, no K40....

All the dash lights are on....everything is clicking, this should be a bad conection someplace. If you have all the lights, the relay clicking but the starter motor is not responding...did you check if you have power on the starter motor with your wife using the key??? I am sorry I am just running out of ideas.

TMAllison · #14 05-30-2010, 03:30 PM

That again usually points to the K40 as the ECU has no power to record a fault.

Might try manually locking from outside using the blade key and then opening with the key fob. Does the auto window open and close work using the key fob?

Note that you are not going to "see" a good or bad K40 relay unless its back cover is pryed off and both sides of the PCB are examined closely under magnification.

MaryA · #15 05-30-2010, 03:44 PM

Thanks everyone! I'm going to pick this up again tomorrow...I'm already in the dog house because it's my wife's car and I didn't get it fixed today...now she's telling me that it's time to get ready for dinner...don't need to be in the dog house for that also!!!

If I was a gambling man, I'd say the K40 will do the trick. Will keep all of you posted tomorrow...hopefully something will be open on Memorial Day.