Crank speed sensor - '93 300TD

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
367
Age
89
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
number crucher is correct by george! and a good post.

there ARE 2x crank sensors on many such cars, and this om603 might have 2x, but the front one does nothing - it is wired into the round diagnostic port and nowhere else. on some odd models (eg w116 with diesel engine) the front crank sensor is used as a signal generator for the rev counter, but as far as i know no uk market mercedes ever used the front crank sensor for any more than a signal to the round diagnostic connector for 'tuning' purposes.

The only thing that I do know is the the front one where fitted was also used to drive the rev counter,,I have the PDF for that mod, this is for the earlier engine though
 

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
367
Age
89
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
In Wis the tach on the 603 engine is added to the front, and as said the later engines have the electronic idle from about 92 onwards.

I have printed off the complete idle circuit for you
 
OP
balge59

balge59

Senior Member
Joined
Dec 5, 2005
Messages
311
Reaction score
1
Location
Nottingham
Your Mercedes
1993 190E 2.0 Automatic
  • Thread Starter
  • Thread starter
  • #43
Well, got it off and tried it but still failed the resistance, so ordering a new one.
Just waiting for TruckpartsMB to get back to me.
For information, the wire was actually just two core, not axial as expected - not copper wires though, looked like steel?

The diagram I am using is at -

http://www.ps2cho.net/downloads/MB%20CD/W124/w124CD1/Program/Engine/602_603/07.1-0400.pdf


last page, seems to match what's fitted, although as I say it has aftermarket DIAVIA a/c fitted. I intend to remove as many connections as I can find to eliminate any problems with that.

cheers!
 

Alex Crow

Senior Member
Joined
Jul 9, 2009
Messages
10,677
Reaction score
47
Location
Super Suffolk
Your Mercedes
W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
wht resistance did you measure on the sensor? if it is 1Ω that may well be fine.
 
OP
balge59

balge59

Senior Member
Joined
Dec 5, 2005
Messages
311
Reaction score
1
Location
Nottingham
Your Mercedes
1993 190E 2.0 Automatic
  • Thread Starter
  • Thread starter
  • #46
put it back with just a little tail, got no change on the meter, tried it on Volts ticking over, got 0.1V, no change when I revved it - just waiting for an email for a replacement

cheers!
 

Alex Crow

Senior Member
Joined
Jul 9, 2009
Messages
10,677
Reaction score
47
Location
Super Suffolk
Your Mercedes
W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
sorry, yes i mean 1Kohms!

balge59, what range were you using on the multimeter? should be AC volts.
 
OP
balge59

balge59

Senior Member
Joined
Dec 5, 2005
Messages
311
Reaction score
1
Location
Nottingham
Your Mercedes
1993 190E 2.0 Automatic
  • Thread Starter
  • Thread starter
  • #48
oops no was using DC Volts? :Oops:
You're right - checked the test it says " >2.8 V`", that means "more than 2.8 Volts AC "doesn't it?
Better retest...:shock:


cheers for that missed it completely...

well retested it nothing on AC, or any of the scales on Ohmmeter
New part on order, next to check the ELR...
 
Last edited:

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
367
Age
89
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
That does show that it is OK
 

dieselman

Senior Member
Joined
Feb 10, 2001
Messages
6,017
Reaction score
12
Your Mercedes
A diesel
Engines like my '95 E300D and earlier, the fuel injection is *purely* mechanical (they're very old fashioned). Once the engine is running, you could remove *all* the vehicle electrics, and *all* the vehicle's vacuum system, and the engine would still be running. With a few odd exceptions, this is true for all pre W210 diesels.
I think some late W124 also reverted to electronic control for the pump, but am not certain about that.
 

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
367
Age
89
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
I think some late W124 also reverted to electronic control for the pump, but am not certain about that.

They did around 92 and the 124 started with it in 07-91 I printed off the info sheet, very confusing as it also says fitted to 603 engine without air con from 1985,, that was when the 124 came out
 

dieselman

Senior Member
Joined
Feb 10, 2001
Messages
6,017
Reaction score
12
Your Mercedes
A diesel
They did around 92 and the 124 started with it in 07-91 I printed off the info sheet, very confusing as it also says fitted to 603 engine without air con from 1985,, that was when the 124 came out
I think that's for the idle speed control that NumberCruncher has mentioned. I thought very late W124 with OM606 engines went to electric control of the main fuel pump functions. I may be wrong though.
 

Bolide

Senior Member
Joined
Sep 17, 2002
Messages
3,294
Reaction score
4
Website
www.w124.co.uk
Your Mercedes
BMW 525 Diesel Touring
AFAIK the RHD W124 with 606 diesel only had electronic speed stabilisation via the pump rack

If you hook one up to the MB handheld tester you can do one thing only - vary the idle. There doesn't seem to be anything else electronic on the car

Nick Froome
www.w124.co.uk
 

Alex Crow

Senior Member
Joined
Jul 9, 2009
Messages
10,677
Reaction score
47
Location
Super Suffolk
Your Mercedes
W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
as above, and per number crunchers post, the 124 RHD never had any electronic pump control other than idle speed, right up to the very last om606. yes there was egr and variable resonance flaps (or whatever they did when they were working), but nothing truly clever with the mechanical pump. these would indeed run all day as long as diesel was flowing.
 
OP
balge59

balge59

Senior Member
Joined
Dec 5, 2005
Messages
311
Reaction score
1
Location
Nottingham
Your Mercedes
1993 190E 2.0 Automatic
  • Thread Starter
  • Thread starter
  • #55
Well, TruckpartsMB came through this afternoon, new sensor arrived - very prompt, BERU branded, good price too - cheaper than s/h on weebay.... Websites a bit pants but their phones work ok!
Be fitting it tomorrow and finish testing - hopefully see some improvement!
Must remember to go round and make sure the a/c wiring is completely removed first, too

Thanks to all for tips!
 
OP
balge59

balge59

Senior Member
Joined
Dec 5, 2005
Messages
311
Reaction score
1
Location
Nottingham
Your Mercedes
1993 190E 2.0 Automatic
  • Thread Starter
  • Thread starter
  • #56
Tidying up! New sensor got the tach working, allowed me to continue troubleshooting the ELR - http://forums.mercedesclub.org.uk/showthread.php?t=69217

The sensor is below the starter, 5mm allen. Looked like it was obstructed by a nearby pipe, but slipped out as if it had been designed for it.... Only way to it was from below, even with airbox top off

once again cheers for all the help!:D
 

Gary Riley

New Member
Joined
Apr 30, 2017
Messages
6
Reaction score
0
Your Mercedes
300D/1993/OM603,Marcos V6 1970
hi
been doing a bit of digging, suspect my tach/tickover problem is down to a faulty speed sensor, but I couldn't find the connector (L3x), or the sensor itself :Oops: so tested through the diagnostic port - presumably the resistance should still be same-ish, 2 k Ohm?
-

http://www.ps2cho.net/downloads/MB CD/W124/w124CD1/Program/Climate/83-570.pdf


The pics all show left hookers, should I be looking behind the battery or the fusebox for L3x?
Is the sensor easier to get at from below or do I need to take off the airbox or something maybe?
I will be digging in again over the weekend but any tips in the meantime appreciated.
Also, couldn't find a part number on EPC, anyone got an idea how much these run out at?

cheers!
Hi just been reading a bit of this thread and found it useful. I have been under the car and I think the crank sensor is located on the bell housing above the earth strap. I too was interested in how the solenoid valve works on the rear of the injection pump. There was some talk elsewhere on the internet that it was pulse-width-modulated. Fortunately I have worked in engineering and electronics for over 30 years so can do most jobs myself.
I have bought the 300D as my everyday car and also have a Marcos V6 with no silly electronics on it, and it doesn't have bio-degradable wire insulation either.!!!!!!
Best wishes - Gary.
 


GAD was founded in 2009 where we developed bespoke ECU Remapping software for motorsport clients, moving forward, we have extended to road vehicles for both performance and economy,
contact GAD Tuninghttp://www.GADTuning.co.ukto discuss your requirements.
Top Bottom