Specific Diagnostic W124 Query

[Andrzej]

Does anyone know what a code of 17 flashes on pin 8 of the 16pin diagnostic connector is on a 1989 W124 300E means?

 

[grober]

Flashcode 17

I have several flash codes listed as 17 . Not sure what your injection system is probably Bosch KE3.5 JETRONIC if your engine no is 103.985 or similar

Throttle switch (TS )full load switch- system unknown
idle speed control valve (ISVC) or ISVC circuit-system unknown
oxygen sensor (OS) or OS circuit - system (KE5.2 JETRONIC)

sounds as if your lambda sensor might be faulty or disconnected, but I would check the other items also.

 

[Andrzej]

It is a 24v sportline model and a 104 type engine. I'll have to get the exact engine code I think! Thanks

 

[grober]

It would have helped if you had said it was 24v 104 engine in your original post!
The engine listed for the 300E-24 is 104.980 as you said with a KE 5.2-JETRONIC/EZL IGNITION.
.
listed for the EZ-L ignition under 17 pin 8 is
Vehicle speed sensor (VSS) or VSS sensor. I dont have any more info sorry.

 

[Andrzej]

Thanks Graeme, sorry, yes I should have been more specific.. hmm. I'm guessing that the vss sensor is actually the crankshaft speed sensor... but then I am getting an AC voltage reading from it and the resistance across the sensor looks to be ok too. Maybe there is another sensor after all...

 

[w124coupe]

I have the later HFM 104 car so don't have your codes....

There is a hall effect vehicle speed sensor on the back of the instrument binnacle next to the speedo cable - output from here is affected by sticky speedo cable - does the needle jump around?

Also, ABS cars have speed sensors at all 4 wheels.....have you had the ABS light flashing at all when it shouldn't?

 

[Andrzej]

The speedo needle has been fine, though I will check this as I did have the instrument cluster out not long ago. ABS has been fine with no warning light so far.. Either way at the moment the car is cranking over but not starting, and this is the only diagnostic error that I can find. Would the hall effect sensor if faulty, or disconnected create a situation where you can't start the car..? Thanks

 

[grober]

Vss

QUOTING FROM THE MB 124 MANUAL. The vehicle speed signal is fed into the central unit by the Hall effect sensor for controlling idle speed. Idle speed control is switched off from a speed of 1.4km/h to improve performance in de-accelleration mode. I cant see how this would stop a stationary car from starting myself but cant say for certain since these systems depend on many different inputs to operate correctly. Maybe best to go back to basics to get some more clues. IS THE ENGINE GETTING FUEL? IS THERE A SPARK AT THE PLUGS?

 

[Andrzej]

I'll check this out over the weekend. I've got fuel etc, but no sparking. I've checked coil, all is ok. The OVP relay seems ok and no other diag codes are being reported - just a single flash indicating that all is well..

 

[Andrzej]

Thanks for help so far. I found the VSS hall effect sensor (plugs into the back of the speedometer), all connected ok - I haven't swapped it yet as I'm convinced that this, if faulty shouldn't stop the car from actually starting (sparking). Anyway I missed one diagnostic pin - that is pin 3. I'm getting codes of 13 and 30 back. You wouldn't happen to know what these mean? Sorry for this I've searched for a listing of codes for this engine and haven't found one anywhere...

 

[grober]

I dont have a pin 3 connection on my 16 pin diagnostic socket?? Pin 3 is reserved for emissions on USA models with the check eingine warning light system I was told once. I got most of my info from a Haynes manual in the library. It was the HAYNES MANUAL 3472- diagnostic fault codes manual. It wasnt completely accurate either I,m afraid. These older diagnostic systems were not standardised very well till the OBD standards were introduced in the mid 90s so its a bit of a minefield !!! Are you sure its getting fuel and its not the fuel pump relay- do you hear the pump run on switching on the ignition. The other possibility is a dodgy alarm/immobiliser system or your EZL unit is faulty- They overheat when the heatsink compound between the unit and the body dries out.

 

[Andrzej]

Thanks Grober. Really sorry I actually meant to type pin 7 and not pin 3! I think I was so busy trying to remember the number of flashes... When I turn the ignition I can hear the fuel pump. I can't see any immobiliser fitted anywhere, and the EZL does return the voltages that I've been advised mean that it should be ok. I've checked the AC voltage of the crank sensor as well as it's resistance to groun which all checks out ok too. I think I'll have to buy the Haynes manual that you have. If you don't mind checking to see what it says for codes 13 & 30 on pin 7 that would be really helpful thanks!

 

[Andrzej]

Actually now I'm not sure which pin it was. I'm going to have to check again...

 

[Andrzej]

Yes - definitely Pin 7. Codes 13 & 30... Would be very interested to know what your Haynes book has to say on these... thanks!

 

[w124coupe]

According to Braingears pin7 is the automatic a/c ECU - can't find code descriptions (yet).

 

[grober]

Tps

According to Haynes the EZL codes are on pin 8. Maybe you mean that rather than 7?? Anyway it lists 13 as TPS(throttle position sensor) or TPS circuit.
I couldnt find anything meaningful for 30 sorry.

 

[Andrzej]

Thanks Graeme. I'll check the TPS out. Shame there's no listing for 30... I'm only getting code 17 on pin 8 which your Haynes book suggested was the VSS sensor. Everything else checks out fine. I might start a new post asking if anyone knows what the code 30 might mean.

Thanks again!

Andrzej

 

[w124coupe]

As per my previous post - pin 7 is the A/C diagnostic. Stick to pin8 for your engine ECU codes.

 

[Andrzej]

Thanks, yes I thought it might be too, but I'm ultimately trying to work out why I can't start this car. The engine turns over and is getting fuel but something is stopping the sparking taking place. Although I'm reading some errors from the diag socket, none of these so far seem to be for anything that should stop the car from starting... The OVP, crankshaft sensor and EZL all appear to be ok (I've tested outputs and inputs and they appear to be within range...). I'm now just completely at a loss over what the problem might be..

 

[w124coupe]

As you have no spark:

The primary on the coil is controlled by the ignition controller based on the input from the crank sensor. When the primary voltage drops, yo get the spark from the secondary.

Check that the coil is being switched via a test light on the negative side of the coil and see if it blinks when the car is cranked. If the light stays on then the controller isn't switching the coil (possible dead crank sensor or wiring between it and the controller). If it blinks, problem may be in the distributor/rotor/cables:

Coil test (resistance) Primary (pins 1 and 15) 0.36-0.4 ohms. Secondary (pins 1 and 4) 7-11Kohms. Check the button hasn't "popped".

Check all ingition cables - 1kohm from contact inside dist cap to plug cap.

Rotor arm 1kohm from centre contact to edge contact. Makes sure the cap isn't grounding somehow.