michakaveli

It was about $100 when I bought mine. Best thing to do is to go to the stealership with your VIN, to make sure they pull the correct part number.

The K40 is the achilles heal of the w210 chassis. (As posted before )

severecaraddict

I get a pretty decent discount through the dealership here. There are some Bosnians here to buy up all the BMWs and Mercedes they run across cheap. I thinking I'm just going to price the car to get my money back out of it and let it go. Or I'll just fix it. I'm just super frustrated at MANY different things and unfortunately I'm taking it out on the car because its an easy target and the latest headache in my life.

TMAllison

I'd lock and unlock the door using the balde key first and see if it clears up.

If it doesnt, the K40 or the car battery itself could be at fault. One provides and the other distributes power. Low voltage can cause all kinds of faults.

severecaraddict

I keep doing that but its not clearing up. I unhooked the negative side of the battery to let it charge overnight and I'll start again in the morning. while it was sitting I was able to get her cleaned up and looking spiffy. She really is a nice car and despite my current problem, I'm still happy with it. Hopefully things work themselves out.

michakaveli

If you do whats been recommended, you should be OK.

severecaraddict

Thanks to both of your for your time, patience, and information.

severecaraddict

The battery fully charged up overnight, so I hooked everything back up an still the flashing green/red lights, no start, and no tachometer. I've tried locking and unlocking the door with the key a dozen times and still nothing.

I priced it to some people this morning for $3k. They're suppose to come look at it today or tomorrow, so hopefully they take it and have better luck with it. Its been a neat car but if I get another diesel E-class it will be a 2005 or 2006.

michakaveli

Sooo, did you ever replace that K40 we've been talking about?

severecaraddict

Nope. I don't want to go on a 'fishing' expedition with $100 bills as bait unless I have solid proof that's the issue. I was just going to let someone else deal with it. Is there a way to test the old part?

michakaveli

There's only so much we can help you out. Just to make sure you noticed, everyone that's responded to you, has an E300.

There is no real way to test out that K40 relay (that I am aware of). Anytime someone has issue(s) starting (if not SOV), stalling out while driving, or the alternating lights you've mentioned, it's the K40. It's the easiest thing to replace. You'll be kicking yourself for not trying that one item.

severecaraddict

I completely get where you're coming from, I'm not a n00b to car forums. If I let the car go for $3k I've not lost anything. If I drop money on a relay and it still doesn't work I'm out a $100+ and still have a car that won't start.

TMAllison

The K40 circut board failure occurs when minute cracks develop in the solider joints on the board. Those cracks open and close with changes in temperature. Some people have examined them with a microscope and attempted to repair them. They usually fail again elsewhere.

severecaraddict

Left the key in the 'on' position for about an hour with the battery charger hooked up. I go out and the car starts up as it should but with the faulty instrument cluster per the usual...this time I have a CEL, but the scan tool shows that the MIL is off. I'm getting ready to head to the dealership to see what my price is on a K40 relay. Unfortunately, I've still not read anything that leads me to believe this could definitively be my issue.

severecaraddict

Unfortunately, neither 'K40 relay' nor 'voltage relay' translate to anything at the Mercedes dealer's parts counter. The parts guy went and spoke to a tech. who knew what I was talking about but wasn't sure where it is on the car diagram or the proper 'Mercedes name' for the part.

He printed out a diagram and gave me a list of possibilities but without a part # I'm S.O.L.

michakaveli

Here is the part number player. 210-540-03-72 | 1996-1997

It's the bottom item inside the computer mad house under the hood on the passenger side.

severecaraddict

Thanks! I'll give it another try tomorrow.

michakaveli

Here is a photo.

TMAllison

Front most relay in the box is how I would describe it. The tech must be a noobie if he didn't know what you were refering to; if he's worked as tech for any lenght of time he's replaced countless of them.

Ask your Dr. to be definitive with his diagnosis and see where it gets you.....sometimes you just have to try some meds and see which works.......you could try a new key batt first. The drug store has them usually.

severecaraddict

I guess I'll just have to give it a go with the relay. The only key I have for the car is the Master Key, so no battery to change. As SOON as I turn the ignition into the 'on' position the tachometer needle vibrates up and down ever so slightly (and continues to do so as long as there is power going to it) but neither the speedometer nor the fuel hand move. As of right now its running but the CEL is on, however still not throwing a code. When I shut the car off, it says to 'check engine electronics'. Shouldn't be anything major, that doesn't concern me at the moment.

In the last month, the ETS light has come on intermittently along with (i think) the ABS light. Its not my every day driver, so I just parked it and started driving my BMW again. I got back in it to run it the other day and this is when I noticed it not starting, the lights blinking and the gauges eventually failing.

TMAllison

I can say definitively, that your symptoms usually point to one of three things:

1) Key Fob battery or security issue.
2) Low battery voltage.
3) K40 relay.

The first is dirt cheap.
The second you can test.
The third cost ~$100 and is easy to change out.

You do hear the SOV click open when the key hits pos #2 every time right? If not, go straight to #3.

severecaraddict

We can mark off #1 because this is what my key looks like:



I'll take the battery in first thing tomorrow and get it tested and if it checks out, I'll take the part # provided above and order a new K40

I'm not 100% sure what the shut off valve sounds like. I know that just before it doesn't start and the red/green lights to their 'blinky dance' I DON'T hear (what I assume to be) the fuel pump. When the car starts as it should, I can turn the key to position 2 and hear a fairly audible noise from the right rear. It kinda sounds like a muffled cow trying to 'moo'.

TMAllison

You've got a VERY early production 96 with that key.

SOV = Go back and read post #2; should have been the first thing you tested.

severecaraddict

The battery tested good:
946 CCA and its rated for 750 CCA. Mercedes Benz battery that's a couple weeks shy of 3 years old.

I went by the dealer and ordered a K40 relay and it should be here tomorrow. $106.

severecaraddict

Here's a video:

http://s235.photobucket.com/player.s...fs=1&os=1&ap=1

TMAllison

With engine on, press and hold the Rest button for 5 secs until the CCU screen changes to diagnostics mode, then using the AUTO buttons scroll to screen 23. What battery voltage is shown while its idling?