Is additional reprogramming required to install an ecm from another 1999 e300.

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Why are you replacing it? They blow a fuse before the ECU can be damaged.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

Needs to have the VIN programmed so everything matches or the immobilizer will not allow the car to run. That is providing the immobilizer hasn't been fooled/bypassed which can be done.

I got a remapped ECU in mine and the immo was bypassed, bought the ECU and it was plug and play. But if you're talking just swapping ECU from a junkyard car then yes it needs to be programmed.

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'98 E300 Turbo "Juliette"
'85 Federal 300TD

I'm replacing because the obd2 port won't communicate with the scanner. I've done the disconnect the battery and disconnected the sensors and tried to reestablish communication and no luck. The turbo quit working. It seems like the egr is always working. Car has very little power. And I'm not 100% sure but I don't think the transmission is shifting into 5th.
So I'm not driving the car until I can get the ecm to talk to the scanner and see where the problems are.
I did have the BAS and ABS lights on the instrument panel but was able to get them removed.
I can't think of anything else to do except to replace the fuse panel on the passenger side near the firewall. Although I did resolder and it didn't have an affect.
I've checked every fuse and they were all good. Checked the cigar lighter and it has power.
I can't think of anything else to check so I'm thinking it must be a problem with the ecm. But I've noticed that quite a few ecms that were turned in for repair checked out good. So I'd like more options before I remove and ship off for repair.
Any other checks that might allow the ecm to communicate with the scanner.
I did check for leaks from the turbo to the intake manifold and I couldn't find one.
I'm not in a big hurry to correct whatever the problem is and not trying to throw money at the problem either.
I did notice the vacuum lines were deteriorated and possibly leaking and have ordered upgraded silicone hose and will replace all vacuum lines.
Roddy

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There's a TON of stuff you need to do before condemning the ECM,
Check ALL sensor powers and grounds, check to verify all sensor inputs are working.
Watch this video before considering.

https://www.youtube.com/watch?v=hJQ6qnhTgdg

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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

The take away is to make sure you get 5 signal volts coming from the ecu. If signal voltage is rather low then disconnect sensors to see if a sensor is shorted.
I'm trying to get a copy of the wiring diagram to make the process go smoother.
But I've already disconnect the sensors and tried to reestablish communication. But it could be more than 1 sensor.
A rather laborious process but I'm in no hurry and like the guy in the video it's an investigation. A lot to learn. But at one point it'll be evident that a reworked ecm is in order or the bad sensor(s) have been identified.
I really miss my old 85 300sd.
Roddy
Once communications is re established then check individual sensors.
Quite a process.
Roddy

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What scanner are you using ? , it may be the scanner is not up to it.

Agreed you really need the official HHT or Xentry with the 38 pin under hood plug to really diagnose the ECU.

The W210 was engineered with the original implementation of OBDII back in 1996 when it first came out. It only passes the bare minimum legally required (at that time) emissions failure codes out the OBDII port.

The 38 pin connector has serial data links to every computer in the car that provide direct diagnostic access. The only way Xentry works with a W210 is through the 38 pin port.

Generic OBDII readers will not be able to do anything useful with a W210 other than get the handful of emissions related codes from the ECU/TCU.

In later models (e.g. starting with the W211 or W164 diesel models) they included a computer called the CGW (central gateway) that picked up data from every computer in the car and present it to the OBDII port so that Xentry can talk to everything via this port.

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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

Check the turbo vacuum transducer , swap it for the egr one.
Check the hose from transducer to turbo is not compromised.

You will not get an engine light with transducer pipe taken off turbo,I used to disconnect mine so I could run steam through intake once monthly (running svo/wvo) ... that way I could increase revs to a fast tick over without any boost blowing steam pipe out of intercooler pipe air temp sensor hole where the pipe was put in just under manifold join

I'm going to swap the egr and turbo transducers as soon as I get the silicone vacuum hose I've ordered.
I suspect the egr transducer anyway because the egr valve seems to be acting up. And the turbo was working fine on the highway and then no boost. Instead of going 75 all the sudden I was going 60 and no power. I did check the turbo output to the intake manifold and didn't find a breach. So I suspect the turbo transducer as well.
The vacuum hoses on the car are suspect and could be an issue as well.
The scanner I bought is a BAFC products Bluetooth OBD2 Scan tool.
Can't get it to communicate with the Mercedes but it works great with my Buick. The scanner is supposed to work with all cars sold in America from 1996.
But I hear it might not be up to task for a Mercedes diesel until 2001 up.
But the old school disconnect the battery didn't make the cel go out so I suspect a short in one of the sensors. And that's why the cel won't go out.
I'll chip away at this. I know I'm not the only person who's having this problem. I know it has to be something simple. Once found.
Roddy


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CEL will not go until cleared with a code reader and battery disconnecting will not work im afraid

You need to hook it up to SDS to see what the code is and fix it then clear it. Disconnecting the battery does nothing. Mercedes computers are much more refined than that. It isn’t a Civic that’s for sure.

__________________
Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

I just ordered a 38 pin to 16 obd2 scanner adapter. Might take a while but I'll be checking the signal voltage and grounds. In the process in obtaining a wiring schematic.
Roddy

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Stupid question, but did you replace the fuse? I used to have one of those cars and when I bought it I plugged a scanner into the OBD2 port and there was no power to it, and I checked the fuses and was about to say nevermind and leave, and I decided to try swapping the (still good) fuse with another one of the same kind in the fusebox and it worked fine the rest of the time I had it.

Check message #4. I've checked all the fuses. The obd2 port has power.
I wish it was that easy. You were lucky.
Roddy

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