I found a nice '95 E300 with a bad engine and I have '87 300D parts car with a good engine. What kind of wiring issues would I run into going from 606 to 603 in a w124?

Swap trans and driveshaft. .. 603 will shred a .418...
Idle control is different. ..

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I have I use the injection pump from the 606 and all the accesories I love the way it runs with a 5 speed manual transmission

I'm not worried about swapping drivetrain components, I just don't want to get into rewiring the engine harness. The '95s had sketchy wiring insulation right? I love the updated look and interior of the '95, but I still think a '87 300D with the 603 is the best indirect diesel Mercedes ever made, at lest in here in the States.

I am on yet another trip typing this on a plane so I am going off the top of my head for the most part. Very difficult to page back and forth between the browser and iBooks (where I have a pdf of the 124 schematics) on an iPad. No multitasking, ugggh.

Most of the interface between the dashboard and the engine bay comes through a 12 pin connector "X26" in the spaghetti pot below the fuses.

Most of the engine management stays in the engine bay, the harness runs off the rear center of the engine and splits left (toward the fuse box to hit X26) and the other leg goes to the OVP and EDS boxes behind the battery.

In that area is a big power terminal block. The positive battery cable and the alternator leads land here. The leg from the engine harness that picks up power to the OVP lands here too. There are 3 studs. Two big and one little. The two big studs are internally connected and is the main supply terminal for the remainder of the car except the starter, it gets its own feed right from the battery post. The little stud is the D+ alternator excitation signal to the charge light in the cluster.

Since you are going from a more complex to a much simpler engine controls wise it should not be very hard to figure out what ties together across that 12 pin connector to the instruments. A 603 does not have the flap control like the 606. There is an air flow sensor and 2 vacuum transducers on the right front corner that can be ignored. These are for the EGR and ARV. This is not like the 606 if you bypass the EGR.

The EDS also has a sensor and actuator on the IP. Together with the RPM sensor at the ring gear, the atmospheric sensor up by the battery, and the resistance trimming by the brake booster, this is all the controls you need for idle management.

For overboost protection, the 603 uses a pressure wastegate paired with a pressure switch in the manifold and a solenoid valve in the ALDA line that dumps boost above a predetermined point.

You basically have to pass oil pressure, temperature, glow plug, start, tachometer, alternator D+, and a few more things that should be common to both engines.

One thing to watch out for is the aux fan control. A 1987 uses a binary switch in the thermostat housing to switch a relay in the relay box directly to control the fan. 1989+ use a thermistor instead to the ACC. The ACC then drives the relay.

I would go to w124-zone.com and download the 124 electrical troubleshooting manual and study the engine control system.

I was having a daydream the other day of what I would love to do with my 124 wagon: find a mid 90s gas wagon with a blown engine, and do a complete interior swap to include the upgraded electrical systems. If I only had the the time, space, and $$.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Why do people make things more difficult then they are? Is very simple to swap the 606 out and replace it with the 603 like I said use the injection pump from the 606 for the idle control

one problem with that, there is no ALDA on the 606 pump, the alda looking thing on it is an altitude compensation device.

The wiring on an OM606.910 is very very simple - the ELR and EGR cubes control the idle and the three flaps in the intake.

There is a slight difference in the body wiring of how the engine is connected to the gauges etc, but takes little time to sort out if you know your electrics.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

I'd keep the original wiring, all you really need to hook up are the glow plugs and the various sensors and the air-con compressor stuff (I may be missing something). Far far easier than trying to swap in the '87 wiring, but you may need to splice in some of the '87 wiring / connectors. The electronic idle control for the OM603 can be deleted, you simply need to adjust the manual idle control on the back of the pump.

Vacuum may be a little more tricky in order to get the transmission shifting correct.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC