1994 e320 Wiring Harness Id

[Bob Weir]

I'm attempting to identify if I have ORIGINAL or replacement wiring harness. # at connector is 124 440 0410. Photos attached above oil filter. Wire insulation is cracked and bare copper wire is present. Is this part of the "notorious" wiring harness? If not, what's the suggested repair? Another wire spider...? What does it connect and how do I R&R it as it goes through panel? Part #?

is all or only some of the wiring in this model subject to this "detoriating insulation" condition?

Dealer ran codes 139994 Short Test, Codes for EA Actuator, EA Control Module, so per many suggestions, I'm trying to id harness condition before buying parts needed by dealer's suggestion. Re my post http://www.peachparts.com/shopforum/showthread.php?t=147929

Where is the part # located on the wiring harness? And/or where should I peel away outer covering to identify BAD harness?

Thanks to all
Bob

[104.992]

Mine was paper labeled where the harness runs between the battery and the ECU - had to remove the battery to get to it.

[PaulSpringmann]

My car is an '95 E320 Wagon.

The part of the harness you show near the oil filter is separate from the main harness. It's the positive battery cable harness and contains the main wire to the starter and a few other misc wires. I replaced mine because it looked just like your picture. I think the price was < $100 several years ago.

I determined that the previous owner had replaced the main wiring harness; the new harness on my contains a very permanent plastic/paper tag wrapped around one of the wires behind the battery. I can look at it tomorrow and post the part number.

[deanyel]

It's tough to get to sometimes - you may have to actually unplug the source plug behind the battery. But worth it - the only way to really know what you have - dealer parts person can tell you if it's original or a replacement.

[Bob Weir]

Paul wrote
<The part of the harness you show near the oil filter is separate from the main harness. It's the positive battery cable harness and contains the main wire to the starter and a few other misc wires>

So is mine Paul. What parts did you remove to get to this harness?

I've removed the (heavy monster) battery. Is the part # on the connector?

I presume the connector for the main harness is in the foreground of attached pik. What do the connectors behind it go to?

Thanks
Bob

[kidMoBile]

Bob:

IIRC, the tag is a white paper (or plastic) sticker that's wrapped around the harness right behind the battery, just before the harness makes its way through the main firewall and onto the top of the motor. The tag has the part number printed on it, as well as a born-on-date!! Month, day and year are all there.
If you can't find a tag, take a look at some of the exposed wire going to the top of the thermostat (or other points off the harness). There should be a couple wires sticking out from the black plastic sheathing of the harness just enough for you to check the condition of their insulation. Mine were cracked; of course yours may or may not be, even if the harness is original. But cracked insulation would indicate an old harness. You really don't want to cut into it unless you really need to!

Brian

[kidMoBile]

Yes, you are correct, the main harness is the big connector in the foreground on the computer. Follow it to the firewall and you'll come across the tag.
The harness passes from the battery compartment, through a slit at the top of the firewall and into the engine bay at the back top of the motor. It then runs into a plastic chase that is underneath the metal access panel that's on the very top of the motor covering the coils (held on by several hex bolts), and gets distributed to a bunch of electrical thingies after that!

In the last photo you posted, I think I may actually see the tag (or if it's not the main harness tag, it looks just like it!). To the right of the computer in the pic is the OVP (overvoltage protection) relay....it has a white plastic top with a clear plastic porthole to look through. If you haven't replaced this yet, do a search on OVP relay. Just to the right of the OVP looks just like the white tag we are describing, but I can't be sure if it's the right one. Just follow the harness away from the big connector on the computer until you hit a tag.

brian

[PaulSpringmann]

Bob

Brian is right, that tag behind the OVP that says "Delphi" is the main harness part number tag. That's exactly how mine looks.

Regarding the partial B+ harness near the oil filter, it's straight forward to replace; it snakes between the firewalls to the battery. There is a plug connector near the brake booster on the firewall; then wires down to the starter and one to the oil level sender. I don't think this set of wires would direct cause running issues because these are just wires tothe starter and idiot sensors. However, they still could short I suppose and create other bad things.

as ever
Paul

[Bob Weir]

Thanks guys
The label in the pik is on a cable with connector to wires 2 Red/Blue and 1 Brown, but appears to go to module mounted behind connectors on left (looking from front to rear of car). I doubt it's the label I'm looking for.
Label reads 124 440 5632 Pers. Nr. 76881 F.D. 05.06.01 Z.D. 11.03.93

Because I couldn't find a label on the fat cable from the connector, even after removing from bundle and using flashlight to look under firewall; I sliced insulation of harness in tray above fuel rail and a connector at thermostat. Insulation is ok at these 2 areas. Is there any other recommended place to check insulation?

Brian
You referenced the OVP replay. Are they problematic?

Paul
Your reference to "partial B+ harness near the oil filter" going behind firewall.
I can locate wire to battery terminal, but not Brown/White wires. Where do I find other end?

Thanks
Bob

[PaulSpringmann]

Bob

That number, 124 440 56 32, is the updated main wiring harness part number according to my EPC (which is a couple years old). This is also the number on the harness in my car. It's also referenced in other posts as the updated harness part no. (searching for "124 440 5632" and "1244405632" turned up a couple other posts). That seems like a pretty early manufacture date on yours; the tag on my shows a manufacture date in '97. Perhaps MB realized very early on that the harnesses were flawed and they redesigned it quickly

I can look at the B+ harness later today; my recollection is that the it splits between the firewalls. The big wire obviously goes to the battery; the other part goes the other way to a plug near the brake booster between the firewalls.

On the OVP relay, they do seem to fail. Mine did and I had to have the car towed home. Others on the forum have taught me that the OVP on these cars powers everthing, fuel, spark, etc.; i.e. if it is faulty the car won't run. On earlier cars, this is not true and a bad OVP simply causes the car not to run right.

Paul

[kidMoBile]

The OVP relay is one of the very common problem areas with our cars along with wiring harness, throttle actuator, climate control unit, AC evaporator, etc etc.....

The original OVP design was flawed and the unit was replaced with a new unit with a different part number.

original OVP (defective): 000 520 52 45

new OVP: 000 520 67 45

The number is stamped right on the side of the relay, most likely in the back where you can't see it unless it is removed
A bad OVP can cause ALL kinds of driveability issues. Search it and you'll be reading for quite a while.

Phil has OVP's here at fastlane for $72-ish.

There were three different harness part numbers for the W124 M104 engine 1993-1995 model years. They were ALL made with degradeable wires, they just had subtle differences in connectivities to peripheral stuff.

I don't think Mercedes put out an "updated" (new) part number on the new harnesses......that would be actually admitting that they did something wrong when they originally made them out of biodegradeable wires....and we know that won't happen! I think the part number remains the same as the original, and the only way to tell whether it's made of non-decomposing wires is to check the born-on-date on the tag (or look for decomposition!). When I replaced my harness, I ordered and received the same part # as the original.

They put bad harnesses on cars starting in 1993 and lasting all the way through the rest of W124 production, if I'm not mistaken. My car was manufactured in April of 1995 and had a bad harness. So, since your car is a 1994 model, then its original harness was made from degradeable wire.

BUT the tag you have seems to have TWO dates on it. I don't remember mine having 2 dates; I'll have to take a look. One of the dates is 2001, so my guess is it's been replaced. but what's the deal with the 1993 date?

Brian

[Bob Weir]

Paul

I'm assuming the "Z.D. 11.03.93" on the label is the production date. Does MB use dd.mm.yy or mm.dd.yy?

< B+ harness... my recollection is that the it splits between the firewalls. The big wire obviously goes to the battery; the other part goes the other way to a plug near the brake booster between the firewalls. >

It appears that removing the screens between firewall and wiper is the way to access this harness. I'll just use my 8lb. hammer and 3' crow bar. I'm searching my 124CDs, but haven't found any reference yet. Do you know of any?

Thanks for the tip on the OVP.

Bob
PS Mine is Ice Blue Metallic w Parchment Tex - Wanna trade?

[Bob Weir]

Brian
Fortunately, mine is "new OVP: 000 520 67 45" I used 2 mirors to read #.

<BUT the tag you have seems to have TWO dates on it. I don't remember mine having 2 dates; I'll have to take a look. One of the dates is 2001, so my guess is it's been replaced. but what's the deal with the 1993 date?>

Are you refereing to "F.D. 05.06.01 and Z.D. 11.03.93" for dates? If so, what does "F.D." and "Z.D." mean? "Nien sprechen zie Deutsch" is all I rember from high school.

Bob
PS Do you think Phil will take island shirts in trade for parts?

[PaulSpringmann]

Interesting... I just rechecked the tag on my harness and it has what appear to be 2 dates as well:

F.D. 26.05.97 and Z.D 07.09.94

The Europeans to like to use dd.mm.yy, I think.

Also the EPC does show that 124 440 56 32 replaces 124 543 90 33, but who knows for certain the exact reason for the new part number.

I guess when I was looking at my harness a couple of months ago, the combination the "97", the superceded part number, and no signs of deterioration lead me to believe that my car has a new/good harness.

I did confirm that the B+ harness splits in the firewall and plugs right next to the brake master cylinder. The piece of the false firewall directly behind the engine is is removeable. Pull up the weather strip, you should be able see how it works.

as ever
Paul

[PaulSpringmann]

Bob

Just to add more frustration here, my failed OVP relay did have the "new" part number.

Paul