My wife’s 94 E320 (155000 KM) failed to start after she returned to it from shopping. Started and drove fine to the store. The battery is fine, lights strong all dash lights come on fine but it does not crank. I tried the 3 things noted in the archives:

· Lock and unlock the doors from both sides in case it is a security system switch.
· Put it in neutral to try and start.
· Jiggle the ignition switch and try it a number of times.

All to no effect. I did however notice a soft buzzing (about 1/3 the volume of the “key in & door open” buzzer) coming from under the dash approximately near the head light switch, when the ignition is turned to the on position.

I towed it home with my Jeep this evening, so it’s now in the garage. Any ideas on the next course of action?

Thanks,

John

I had the same problem with my 96 E320 a few months ago. I immediately (AND WRONGLY) eliminated the battery as the problem since the lights come on nicely. But you need to check the battery with a voltmeter while turning the key to cranking position to see if it will maintain the necessary voltage (mine dropped precipitously to 7V), because the starter motor requires significantly more power than the lights.

I am not sure if yours has one but, it is a known problem with the older E's. Can you hear the pumps working when you turn the key?

__________________
J.H.
'86 300E

OVP?

Do a search for OVP or over voltage protection relay.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Thanks for the comments.

No luck but I have eliminated the following:

· All fuses are OK including the ones on the relays behind the fuse box.
· Charged the battery just in case (didn’t take much) then lifted the car, shorted the solenoid and it turns over fine, so its not the solenoid, starter or the battery
· Had a look at the over voltage protection relay and it does have the newer part number and the fuse on top is fine.
· For a few seconds after turning the ignition on I can hear the fuel pump run then shut off.
· The buzzing I hear when the ignition is turned on, is I believe the headlamp relays. The part number is 201 821 0047 with DOT SAE and 12V 2 (4) 21W markings.

Any comments on why the above relay is buzzing, and how can one tell if the OVP is bad?
Anything else I may be missing?

John

Spent some time reading most of the OVP threads and none seemed related to a no crank (turnover) problem. I therefore thought it was more likely the ignition switch. So this morning I turned the ignition switch on, lifted the car, shorted the solenoid and voila instant start. So I’m off to pull the dash apart unless anyone has any other item to check for.

Thanks

John

Check the Neutral Saftey switch.

What does 'Lifted the car" mean ?

I had a problem with the steering lock, which is a T shaped piece of metal with the lock cylinder on one side and the ignition swicth on the other. A piece inside this T broke off, so when you turn the key nothing would happened. The key buzzer switch is in attached, or in the inmediate vecinity of this piece, and may be that is the buzzer that you hear.
I suspect either the steering lock or the ignition switch itself.
You have to remove the lower dash part of the dash to get access to it. Again, that is based on my model year. Yours may be different.
Good luck!

__________________
J.H.
'86 300E

Lifting the car means raising it on the hoist to gain access to the starter, which you can only do from below.

I now have the ignition switch out but the local Mercedes parts is closed till Monday. Anyone know which pins should show continuity to engage the starter so I can be sure it’s the switch?

As for the neutral safety switch I did try starting in both park and neutral but if that is not sufficient can it be bypassed and/or tested?

Sorry for the somewhat basic questions but I have only owned this car for about 9 months and have not had a chance to pick up the shop manual CD.

Thanks,

John

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My 240D Gallery http://www.peachparts.com/shopforum/vbpicgallery.php?do=view&g=290

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The N safety sw. [ "starter lock-out switch" on the schematic]
shows therminals 3/4 for starter circuit . [ 1/3 are back-up lamp]
*The sw is a 4 prong , 2 independant sw circuit. The location is drivers side of trans. There is also a plug under dash, above gas pedal- 4 prong, x/49/2 connector- same deal-pins 3/4, v/wh- v/gn.]

The internal contact points for both N and P are the same, but the operating cams are different. [ the reason why , in some cases , if you do not have a start in P , we recommend the N attempt... only temp to get you out of a tow jam- if it starts in only one , change it fast as it is on it's way].
The problem with this sw is they are prone to moisture/road dirt
BC of their location..... fairly easy replacement part if you have a lift..

Just a note in conclusion: It was the neutral safety switch, which I replaced before purchasing a new ignition switch. So I became a little more familiar with the dash than I needed too, but at least the problem is solved.

Thanks to all for the assistance, especially Arthur Dalton who nailed the problem.

John

__________________

My 240D Gallery http://www.peachparts.com/shopforum/vbpicgallery.php?do=view&g=290

First of all I really want to thank you for helping all of us !
From your comments below and from your other posts I am thinking mine problem is also same. I am "very" layman when it comes to cars, I have few question if you can help/educate me.

1- what is neutral safety switch and where it is located.

2- in my case there was no response when I turned key to cranking position, but it got started when I moved the gear stick only first time and that is it. since then I tried playing with gear stick but all in vain. Does this tells/confirms that the problem is neutral safety switch.

3- If problem is neutral safety switch does need to be replaced and how much app it costs.

4- If it is under the car can I reach it without lifting the car.

Mine OVP shows the new part -- 67-45 , what is suspect in you view OVP or neutral safety switch

Thanks in advance