Need help on a few electrical connections '94 E320 Wgn - PeachParts Mercedes-Benz Forum

92-2.6 · #1 03-23-2011, 02:14 PM

I have a wagon that I bought in a non-running state due to a failed engine wiring harness, and a fried dash harness. The rest of the car was perfect and the price was right, so I thought I'd replace the wiring and give it a go.

This project has taken way longer than I had anticipated, and as a result there are a few wiring connections that I apparently failed to document in the removal process, or had been done prior to my purchasing the car that I need help with.

The first couple should be easy the third maybe not so much:

1) From the positive battery terminal there is a small lead that appears to go to the group of connectors mounted on the strut tower. I'm not sure which of the three posts this is supposed to connect to, or even if that is the correct spot for this lead.

2) On the engine harness there is a two wire connector that appears to connect to someplace under the intake. I'm not seeing where that is supposed to go

3) Under the dash looking up to where the fuse box resides there is a group of connectors that mount just to the right of the X30 connection where all the heavy gauge red wires go. There are a series of two prong connectors that all plug into each other and mount on the outside of the fuse/relay box housing. I need to know if there is a specific order to how these are connected together. Also is there any good way to get the center plastic pin to pull out of these connectors so they can be taken off the flange they're mounted to? I've tried every way possible and cannot get these to come out.

I have the w124 manual on CD, but I haven't figured out how to find these specific answers in there.

Thanks,
Dean

Bob Weir · #2 03-23-2011, 06:21 PM

Sorry I can't remember the item [sold my Benz], but if you go to Section 24 Electrical Troubleshooting in the CD Manual you should find an illustration.

You can also go to the same parts catalog the Benz dealer parts dept uses.
Go here...
http://epc.startekinfo.com/epc/welcome.jsp

In the event the electrical plugs and a few inches of wire to the stereo are ok, I'd like to buy them if you're not going to use them. I want to put the stereo from my 94 e320 into another car, but need the plug end so I can wire into another car.

Good luck with the rewiring.

Post photos that should help us ID what you're trying to rewire.

Jim_P · #3 03-23-2011, 09:23 PM

Do you have a picture of the 2-wire connector? There are 2 knock sensors with connectors like those of the fuel injectors and there is a 2 wire connector that has to round holes that goes to the idle air control valve on the bottom of the upper mainfold just to the left (drivers side) of the throttle actuator.

-Jim

92-2.6 · #4 03-23-2011, 11:49 PM

Thanks for the responses. I found that the lead from the battery goes to a spot on the strut tower. (See photo) There are three posts on this connector, and someone from another list said it belongs on the left most post. Let me know if this doesn't look correct.

The harness connector does indeed go to the underside of the air intake.

The connections under the dash are still a challenge. Here are some photos of the wires in question.

Bob, as part of this process I "Harvested" a couple wiring harnesses. They're not complete, but I do have all the radio connectors as far as I know. Let me know what you need and send me your address. They're yours for the price of the postage.

92-2.6 · #5 03-25-2011, 01:47 AM

Well I think I got the #3 question sorted out. It looks like everything I had left all pretty much hooked together. Below is a photo of what it all looks like plugged together.

I still have two connections with unknown mates. One is a single wire connector, and the other one comes off the steering column. I'm guessing this one is part of the airbag system, but not sure where it belongs either.

I took a chance and tried hooking a battery up to see if magic smoke appeared anywhere. So far so good there, but I'm getting a couple really weird things happening. First is that the battery light is on all the time. Doesn't matter if there's a key in the ignition or not. The second issue is that there is a hum or buzz coming from the intake area of the engine. Again this is when nothing should be on at all since there isn't a key in the ignition.

I had my wife try to start the car for the heck of it, but there wasn't anything. Not even a click from the starter. All the relays and fuses are in place. No fuses blew in the process, so I guess that's good.

Any thoughts on what might be up other than something isn't hooked up right?

Stu Ritter from the Mercedes list turned me on to another site that he said should have the schematics for the entire car at www.startekinfo.com. Unlike the Mercedes parts site you have to pay to access it by the day, week, month, or year. Pricey at $18 just for one day, but I'm going to give that a try next.

-Dean

Ferdman · #6 03-25-2011, 07:08 AM

Dean, you're a brave soul buying a non-running car with those problems. Are you sure the 124 Service Manual CD doesn't have wiring diagrams on it?

Bob Weir · #7 03-25-2011, 09:55 AM

Hi Dean

I'll take a wild guess at this one...
"I had my wife try to start the car for the heck of it, but there wasn't anything. Not even a click from the starter."

"Battery aka "B" Harness
from connector 3 wires;
Br/Bk to Oil level sender [front lower left of block],
Br/Gr Oil Pressure switch [below oil filter]
Purple/White Solenoid {on Starter} <= this one for NO start

More info and photos here =>
'95 E320 wire harness question

These 3 wires can easily be made, but be careful disassembling connector [3rd photo] because you need to use it's internal connectors.

vstech · #8 03-31-2011, 01:55 PM

wiggle the ovp relay... buddie's ovp causes the starter not to engage...

92-2.6 · #9 04-11-2011, 12:24 PM

Update:

I followed the procedure A. Dalton outlined for a fellow w124 owner a couple of years ago to isolate the K38 relay and S16 NSS from the starting circuit. Still nothing. I turned the key to the start position and jumped directly from battery positive to the middle post on x27 and the engine sprang to life. Wonderful! Except it wouldn't turn off!?!

I could pull the key completely out of the ignition and it did nothing to affect the engine. I wound up blocking the air intake to choke off the engine.

I have verified that the NSS works properly using an ohm meter. The K38 doesn't click at all, so I'm guessing it isn't getting power. I have no functioning dash instrumentation, so that would seem to indicate there's no power on those circuits either. No brake lights, reverse lights, nor turn signals, but the headlights and interior lights work fine.

I cleaned all the contacts for the fuses and replaced all the fuses with new ones. All I could find yesterday were really poorly made Buss fuses. At least they were cheap since I'll be replacing all of them again with better quality ones. I'll pick up some good ones today.

Could the other issues be the result of a bad ignition switch? I searched through the forum, but didn't find anything related.

Thanks again for everyone's help.

-Dean

aTOMic · #10 04-12-2011, 11:57 AM

There's a connector on the driver side fender (pictured here) that had bad corrosion (on my '96) but looked OK until I popped the cover off. You may have eliminated it already, not sure. It goes to NSS/BU light switch, and is present on the previous E-series (W124 I think) and on diesels.

Thanks Jeremy for the pic, original NSS no-start thread is here.
HTH

92-2.6 · #11 04-13-2011, 12:31 PM

Thanks aTOMic. I think this is similar to the connector that's mounted on the left side of the center console in the w124. Where the NSS ties into the circuit.

I harvested some parts to try from a junkyard e320 yesterday, but all had no effect on the symptoms. I swapped in a new K38 relay, OVP relay, ignition switch and even tried a different ECU. None had any effect, so it's obviously something connected wrong or still not hooked up.

I looked a little further in the wiring near the center console to see if something there could be causing the problem. I hadn't re-installed the console as I wanted to make sure I had the wiring correct first, so the radio, window switches, etc haven't been hooked up at all to this point. I wouldn't think those would impact this situation, but since the ATA system seems to have far reaching powers maybe this is related. Honestly I don't know. However, I found a couple connectors on the left side of the console that I thought were related to the radio, but might not be. One has four wires coming off of it and the other has three. They are basically flat, but one is slightly S shaped and the other one has one connector slightly offset at the end. I'll snap some photos tonight, and search through the ETM to see if I can identify what these are for.

I did test to see where I have power after my disappointment with the results of the parts swap. Circuit 30 has 12v to the ignition switch, and I do have 12v at the K38 relay on post 78a.