Turn key to start position and no cranking but there is a buzz which I believe emanates from a module within a group directly rearward from the fuse panel. Will attempt to attach image of wife's finger pointing to buzzing vibrating module. In case the attachment fails, the module is forward/center in the group, encased in black plastic and roughly 1"wide x 3" lg x 2.5" tall (from memory not measurement)

Son reported buzzing sound started when he was slowing for a car backing onto the roadway. Pulled over to stop and investigate but couldn't restart the car.

Thanks for any help/similar experience.

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Can you pull it out and get a part number off of it? Are you sure it didn't always buzz?

It is a pronounced buzz and vibration that can me heard easily from the driver's seat with the windows closed. Quite sure it wasn't happening before. Probably can remove the module (already did pull up with moderate pull and it didn't release). Thought it might be smart to better understand the thing I was about to pull hard on to remove/break. Will go ahead with that (hoping just the removal and not the breakage) absent further info.

Module in question is N/10 Combination relay.
Suspect for buzzing N/10 would be low voltage condition.
Charrge battery and retry.

My suspect is you are instead hearing the k38 starter lock out relay behind the dash.
That would fit your complaint.

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A Dalton

August,

This happened to my '95 E420 about six months ago. EXACT same symptons - relay buzzing and car wouldn't crank.

It wasn't the relay that was bad. It was a fuse! I replaced a blown fuse - the buzzing stopped and the car cranked like normal.

I forget which fuse - but it was in the standard fuse box in front of the relay box (not some hidden fuse).

Jim

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Syntax26

1995 MB E420 (lowered)
1989 MB 300SE (sold to brother)
1975 MB 280 (sold)
One damn fine jacked-up golf cart

It is fuse #5 and it is feed for the K38/Starter lock-out relay I mentioned.

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A Dalton

Thanks very much for the help. Will check out and report back shortly.

Well, well, well. Fuse was in fact blown, even though I had glanced over them all. Somewhat embarrassed to say I have been fooled before with a German fuse appearing at first look to be continuous but closer inspection revealed the break. Anyway, thanks again for the help. Also, if there is a significant underlying problem, shouldn't that fuse blow again soon?

this just happened to my 1995 E320 wagon a couple weeks ago. I was coming up to a light and then my cluster went dead and I heard a buzzing, car still ran though. I drove to the nearest parking lot, turned off the car and then tried to start it back up. it wouldn't. just a buzz from the dash. a new fuse 5 and all was good. weird.

AD, my 1995 E320 wagon just had the same issue (7/24), and I placed my hand on the rear of the engine-bay fuse box, and I could FEEL some relay buzzing, and there was NO BLINKING Alarm LED.

Based-upon all the late model W124's having this problem, I wonder if this is some impending failure mode for either the ATA, NSS module, or their respective relays, or OVP ?

In a different thread, I was successful by disconnecting the OVP relay for 5-seconds; locking & unlocking the door a couple of times; and then when I saw the courtesy light on, she started up fine.

Battery was replaced in 2005, and she sat on battery charger for 2-days, and she has a new OVP relay (2-days ago); a new NSS (2-months ago); and all fuses were changed out in October 2007.

Hmm . . .

:-) neil

Same deal...no Armed Led is fuse 5 and that fuse powers K38 starter interlock relay.
So, change the fuse.. if still NO, then check/change the K38 relay.
K38 are troublesome and many Techs just jumper the pins and plug it back in.. You only loose Starter interlock security...

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A Dalton

Fuse 5 was fine. She was changed out less than 1-year.

I think I'll just permanently jumper K38 (silver relay, not blue relay=horn). It's pins 30 and 87, correct ?

:-) neil

Pins 1 and 3 on the connector..30 and 87 on relay...[ NOT 87A ]

Just b/c the fuse has been changed recently means nothing..it is not the fuse that give us the problem, it is the copper holder on the ends of the fuses..they looses contact and have to be cleaned.
That is why we always tell guys to "Spin the fuse " in it's holder..
we also test them with a test lamp on both sides , but at the holder, not the fuse ends ..that tells us if the connection at the fuse/holder is bad..even tho you have a good fuse. Test lamp from both sides to ground verifies 12 V @ both the fuse and the holder...testing the fuse at it's ends can result in passing a V test, but that power does not get to the actual holder connection, so the results are the same as if you have a bad fuse.
They will fool you ...see it all the time.
Spin Them ...even when you replace a bad one ..helps seat them in the holder good a secure.
I personaly don't like that type fuse or holder.

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A Dalton

Neil, check if the OVP relay is buzzing. Just because it's new doesn't guarantee that it's good. Cold solder joints are known to fail on the OVP relays.

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Fred Hoelzle

The buzzing suspect is K38..it is right below the fuse box on the cluster.

OVP is on the other side of the car on that chassis and OVP is not in the starter lock-out circuit. It is ECU feed on HFM/SFI systems and you can take the OVP right out and the car will still Crank. It just will not Start/Run.. Passenger side, behind battery panel.
K38 is Crank/Starter circuit.

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A Dalton