87' 300E - Need help badly with wiring

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BAD300

Active Member
Joined
Jan 30, 2010
Messages
177
Location
Australia
Car
87' 300E Turbo
OK guys, really need help with engine bay wiring. As some would know, my car has had LPG installed by previous owner who did a terrible job.

Now, concerning the wiring. My 300e is RHD so, battery is on left side of car, which is our passenger side! All harnesses have been butchered! No ECU, no EZL, no fuel equipment of any kind. Dedicated LPG through mixer (old set up)

So, I need to know some basic wiring info. I cannot work it out using wiring diagram grid sections etc as, I no longer have original engine harness or anything original for that matter! Googleing is hopeless!

a) To begin with, I need to know what the thick diameter red, cloth-braised wire is that bolts down to a distribution block that sits next to main "fuse block" located front of brake booster on drivers side that runs along in front of heater blower motor & wiper arm assembly that exits out to battery compartment area? Is this originally for fuel pump or does it simply connect to battery? I'm sure you wire separate wires from positive battery terminal direct to alternator &/or starter motor. Is this correct so far? Remember, I don't have original engine harness! Pics below:

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b) Can someone also identify any/all of the harness wires pictured below that exit directly from "fuse block" & also run through to battery compartment, passing through beneath/front of heater blower motor & wiper motor? Pics below:

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c) Can someone also identify any/all of the main wires that run from inside cabin harness & exit through to battery compartment area? Pics below:

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P1010033.jpg


If I don't @ least sort these, there is no way I can attempt the VEMS ECU harness install up ahead........ :coffee:
 
That looks like quite a challenge! If I remember correctly the thick red wire goes to another junction box by the passenger side strut mounting.

Picture 3 is the main loom that connects with the ezl, the ovp relay, the fuel injection ecu, and the 2 ezl timing adjustment plugs. Looking at your picture, that loom should still have the large multi-plug under the fuse board, and it also connects to the blue wire in picture 2.

I have this loom complete removed from a 1989 300e, I am going to use it to run my m103 swaped in to a w208 clk. I'll lay it out on the floor and take some pictures of what goes where.:thumb:
 
In pic 5 the cable on the right look like a domestic 4core wire. (red,blue,brown,green/yellow.)
The cable on the left looks like standard 7core trailer wiring colours.

Could these be non-standard wiring associated with the LPG installation? Deffo don't look of Merc origin.

All brown wires in factory harnesses are earth wires. Without exception.



.
 
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The big red wire is a main 12V supply wire directly from the battery positive. The unit its connected to is a mini power distribution point. Almost impossible to say what's going on with your wiring which is frankly a total basket case mate . I'm also not sure what you want to do exactly- preserve the existing LPG setup or restore the original petrol injection system before modifying that? You really need to return the standard wiring setup if you want to find documented wiring diagrams as to what's going on. You need 2 things- a wiring diagram for the LPG system and a wiring diagram for the standard injection.

this online source for w124 might help- its a bit slow but all the info is there. W124 MBCI - MERCEDES-BENZ BOXER CLUB INDONESIA (W124 MBCI)

what you need is to navigate cd1-- model 300/320E-- 1987---ELECTRICAL TROUBLESHOOTING MANUAL--- WIRING DIAGRAM and choose/download the relevant sections. good luck
 
Just got home from work (massive timezone difference between us). Thanks guys for replies. Much appreciated!

I have this loom complete removed from a 1989 300e, I am going to use it to run my m103 swaped in to a w208 clk. I'll lay it out on the floor and take some pictures of what goes where.:thumb:

That would be fantastic Thanks!
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Could these be non-standard wiring associated with the LPG installation? Deffo don't look of Merc origin

Could be non-standard for sure Thanks for this!

I'm not sure what you want to do exactly- preserve the existing LPG setup or restore the original petrol injection system before modifying that?

Thanks! I will be having liquid injection LP installed once I can navigate the basics & wire in new after market ECU. I just gotta get as much sorted as I can first, while I await parts & fabrication etc......
 
P1010032.jpg


The thick green wire is not used, the large braided wire is the live feed from the fuel pump relay to the pump. The browns are all earth's. The green and yellow wire is the signal to the tacho from the fuel pump relay.
The thin green wire is from the temp sender to the gauge.
 
Thanks, your a champ! I did manage to rip out a harness from a junkyard but still, even with wiring diagrams, you only get half the pic of what's going on inside cabin (to what part each wire actually effects)

I needed this info you have just written.

Cheers!
 
This is the loom I have, not a great picture I know. Without striping the insulation off it is hard to follow what wire goes where.:doh:
 
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Yeah, tell me about it.........

The loom I got from wreckers I stripped But my harness along with fuse box wiring are so butchered, buggered if I can get much of it :wallbash:

Apparently, all I need for the VEMS aftermarket is +12V, earth, tachometer and ignition ON signal.Obviously fuel pump wiring as well.

I think I'm going to hotwire from the fuseblock & go from there.

What a mess :crazy:
 

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