Hello all,

Last week I took out an 1987 om603 (body in collision) and put it into a 1994 E320. I switched a lot of the wiring and vacuum lines over with the 603 along with the instrument cluster.

I am having problems locating a wiring diagram for the temperature gauge and tachometer. I swapped over the ecu with the 603, but can't figure out which wires I need to connect to get the tach and temp guage to work. The engine, ecu, and instrument cluster all came out of the 87' so I am hoping I can make both gauges work like stock. Any advice on how to make these work or a wiring diagram would be greatly appreciated.

Thank for the help in advance,
Craig

I assume you've perused page 12 here. I also have a complete 603 from a wrecked '87 300TD and spent hours dissecting the wiring harness to free up just the essentials required to operate the basic engine and peripheral functions. It's not modular at all. Aren't the '94 wiring systems CAN-Bus?



Here are the basic vacuum requirements to operate these engines, if needed.

Thank you for the quick reply. I don't recall when MBZ went to CAN communication. But the 87' does not correct? I am using all the wiring for the 87' ECU and engine from the 87". So I would assume I can bridge the gap between the engine, 87' ECU, and 87' instrument cluster. But maybe its more complicated than I thought.

I looked at page 12 of the link you sent and I can not seem to find where the ECU sends signals to the instrument cluster. Am I missing something? I don't recall where I got the information, but I thought the coolant temp and tach went through the ECU and then to the instrument cluster.

I have eliminated many of the vacuum lines line in your drawing, but the transmission shift very late and hard on its second shift. Maybe I didn't hook it up right. I ran a line from the vacuum pump to the top of the deal on the injection pump and then a line from the front lower part of that deal to the transmission. The transmission came with the 603 and shifted great before the transplant. Maybe you can point out where I went wrong here. Otherwise I may have to try and add the blue vacuum amplifier back on.

Thank you

I haven't studied the diagram in a while, but I believe the '87 connects back to the instrument cluster via the KLIMA relay. The '87 is not CAN, but I'm not familiar with how KLIMA or OVP are managed on those late-model cars. The early wiring harness ties the ECU in with both of those relays, at least tangentially.

You probably need to adjust both the trans. vac. modulator and bowden cable. The former adjusts the quality of the shifts (soft/hard), while the latter adjusts the timing of the up shifts (which RPM). There's no need for the blue flying saucer (BFS)--these were ditched on later OM60x cars

Thank you again for your response.
Interesting points on the modulator and bowden cable, but what confuses me is why the would be out of adjustment now, but were just fine last week in the 87' chassis. Does removing the blue vacuum amplifier change the vacuum enough to place the modulator and bowden cable our of adjustment?

Does anyone one have a wiring diagram or explanation for the instrument cluster on a 1987 300D and how to get the temp gauge and tach to work? It sounds like it is more complicated than it has to be.

Thanks,
Craig

I put the blue vacuum amp back in and now the transmission shifts as it should.

Can anyone verify how the instrument cluster gets the temperature signal?

Good news.

I grounded the green wire going into the round instrument cluster and PRESTO! The temperature gauge spiked. So I ran a wire from the coolant sensor on the block to the instrument cluster, spliced my new wire onto the green wire, and now my temp gauge works. This was my biggest obstacle in the swap and now I feel comfortable driving it further from home.

Once I figure out how the instrument cluster gets the tach signal, I'll get that going as well.

I also need to figure out how to get the 87" AC compressor going, but thats not a huge deal here in Oregon.

If anyone has advice or comments, let me know.

-
Craig

I'm just 100miles North of you, and I consider AC to be quite important. If you take a look at that wiring diagram, you'll see that relay N6 (KLIMA) handles the AC functions via the compressor clutch and speed sensor, pressure and temp. switches and trans. kick-down functions

I believe they use a completely different sensing mode. The diesel has a sensor on the flywheel close to the starter. Someone else might have a better explanation. cheers Dan

__________________
It's always something simple
91 300D 603.960 (from japan) 194K
92 Toyota Diesel Landcruiser HDJ81-t 116K
02 Golf TDI new head courtesy of PO
87 300D
97 BMW 525 TDS Wagon 5spd
bunch of Onan and other diesel generators

The gasser it's the same has a sensor near the flywheel

I know for a fact the gasser tach will not work in an 87TD wagon... the tachs from two different gassers gave weird readings. diesel tach solved the problem.

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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!