I tried a full digital scan (3 times) and each time, only one module responded with an OK - the other modules responded "module not found or installed".

Your non-MUX unit came with a male connector for plugging into the 38-pin diagnostic connector on your car, but only 3 of those male pins are actually wired (1,3,4). Two of them (1,3) are for power connections, so when you plug-in the interface is wired to communicate with just one system -- the one associated with pin 4 -- and for your car that would be "HFM".

To communicate with the other systems you have to somehow connect the male pin 4 to the female socket of the desired system. To do this "David in Australia" attached one end of an electrical lead to the male pin 4 and attached the other end to a paperclip which he inserted into the various female sockets (picture). He connected the male pins 1 and 3 to his car battery for power.

I used a different method. I removed two small screws and disassembled the shell of the male 38-pin connector. Then I unsoldered the wire to pin 4. With the shell still removed this allowed me to plug-in the connector and use a jumper wire with small alligator clips at each end to connect the unsoldered wire to the appropriate pin for the system I wanted to check (chart).

For live data, try "MSM" and "ME" since there is no selection "HFM". It may not be supported for the SL320.

The Carsoft version 7.6 uses a different communication protocol than version 7.4, so it is incompatible with your interface.

For troubleshooting a check engine light you can go to Autozone and have them read the codes and extinguish the light for free.

I have one of these non-MUX Carsoft interfaces for sale for $100.

 

Al,
I don't know anything about all that digital stuff. You lost me 28 pins ago. I thought Carsoft 7.4 was a car wax.

Make sure your indy checks ALL your vacuum lines. They are the very first thing to look at with a mysterious CEL. The lines are plastic, brittle and just plain piss poor. MB should be ashamed of that material choice. If I were you, I would just have your indy replace them all. Mine did and my CEL went away.

 

Bob,

Thanks for your response. Clearer now. Is buying the mux version the right way to go and eat the non-mux HW? Also, will the mux version clear the CEL by erasing the error codes?

Al

 

Al, I don't think the multiplexer has any advantages other than convenience. If you have a code, then your non-MUX version should be able to read and erase it, but I sense that yours did not...Be sure and check the transmission module, and for pin 4 I would run a digital test selecting "ME" and "MSM" as well as "HFM".

 

Hi all, which code would be the roof control module on a 1994 R129 please? Not sure what ads, di, bas, ea etc means so cannot locate which error to clear. Thanks

 

Look at post 13 on this link:

http://www.benzworld.org/forums/r170-slk-class/1270869-38-pin-carsoft-7-4-a.html

Here is another link

http://www.benzworld.org/forums/w210-e-class/1574129-carsoft-7-4-multiplexer-diagnostic-tool-2.html

A friend of mine just bought this car soft multiplexer tester:

Wholesale Diagnostic Tools - Buy For Benz MB Carsoft 7.4 Multiplexer OBD Communication Interface Cable, $47.4 | DHgate

It works good...

You will need a Windows PC running XP with a dedicated serial port-no USB to serial converters(they do not work). It will run on win7, but only one of the five versions of windows7 will work. The "Ultimate Version" which is the $400 version were it will run in XP mode. it is just cheaper to get a laptop for $100usd with a dedicated serial port...

Hope this helps,

Martin

 

Thanks so much ... Just what I was looking for. Pin 21 seems to be the one for the soft top controller.

I will try again as really struggled to get anything to work on carsoft with my cable set similar to one you posted in the link.

Assume I am right to use analogue via the 38 pin port?

I spent a very long time doing individual tests as on analogue it doesn't do a complete diagnostic.

When I tested RST it wouldn't read it and said 'not built in'. So no closer to fixing it sadly.
I changed the stereo the other day and didn't know I had to remove the green and black wire. This apparently has stopped my roof from working.
I have removed the wire but told I need a tool to reset it.
Given the carsoft cannot read it I doubt it will reset the error code.

To make things worse I just bought another reader/reset tool from the US this week and realised it's the banana type which won't work!?

 

Apologies I should have expounded. Disconnecting the VCC will stop the roof from operating it also may throw a few ASR codes

Reconnect the green and black striped wire and your roof should operate again.
As mentioned the only purpose of the VCC wire to the sound system is to control the volume at various speeds.

Either reset with a code reader or take off (Disconnect)the negative terminal cable from the battery and touch the positive cable connection for a few seconds. Reconnect the negative cable to the battery and start the engine, operate both windows up and down and turn the steering from lock to lock, this hopefully should reset everything.

 

Thanks for the info ... Really helpful. I was told the reason my roof has failed is because when i chnged the stereo i left the green and black attached. This caused an issue as the new stereo presumably has no function for speed signals so grounded out the roof controller?
Interestingly the green and black wire had been cut in the past ... Presumably because and aftermarket head unit had been fitted by a previous owner?

The resetting by touching the battery leads sounds scary! Is that definately safe?

 

DISCONNECT BOTH cables from battery.
Then touch ONLY the (disconnected) cables together (don't let them touch the battery)

 

Thanks very much. And this will reset my roof controller?

 

Can I use carsoft 7.4 multiplexer with Hht-win. Because I couldnt install carsoft software on my laptop.

 

NO

 

What OS is your Laptop running ?
See post #7 above.

 

Windows 10. No rs232 port.

 

NO, it wouldn't work.
See post #7 above.