SL-Class (R129) 1990-2002: SL 280, SL 300, SL 320, SL 500, SL 600, SL 60 AMG

SL/R129: 300 SL OBD1 fault code diagnostic results

Old 09-01-2015, 05:04 PM
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1991 Mercedes 300 SL
300 SL OBD1 fault code diagnostic results

Hi,

1991 300 SL with check engine light diagnosed to OBD 1 Socket 8 (Distributor Ignition) showing 17 flashes which on fault code table suggests Possible Cause of Failure to be "Crankshaft Position sensor faulty".

Also Socket 14 (Continuous Fuel Injection System - MAS Controller) reports 9 flashes which fault codes to "Circuit 50 failure". (note these return even after being cleared).

I'm non-mechanical but any suggestions on what to advise my non-MB mechanic to start looking at based on the above?

Thanks in advance.
Old 09-06-2020, 11:53 AM
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R129
Hello,

I know its been a while you posted this but I have the exact same issue.. have you manage to find what the issue was? Any help would be appreciated.

thanks

Originally Posted by MikeShields
Hi,

1991 300 SL with check engine light diagnosed to OBD 1 Socket 8 (Distributor Ignition) showing 17 flashes which on fault code table suggests Possible Cause of Failure to be "Crankshaft Position sensor faulty".

Also Socket 14 (Continuous Fuel Injection System - MAS Controller) reports 9 flashes which fault codes to "Circuit 50 failure". (note these return even after being cleared).

I'm non-mechanical but any suggestions on what to advise my non-MB mechanic to start looking at based on the above?

Thanks in advance.
Old 09-10-2020, 06:07 PM
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Originally Posted by Mike00135
Hello,

I know its been a while you posted this but I have the exact same issue.. have you manage to find what the issue was? Any help would be appreciated.

thanks
Sorry, nothing new to report since I have not driven the car this year (due to Covid). If you diagnose anything please let me know (and I will do the same).
Old 09-11-2020, 01:02 AM
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Originally Posted by MikeShields
Sorry, nothing new to report since I have not driven the car this year (due to Covid). If you diagnose anything please let me know (and I will do the same).
I have ordered a new crankshaft position sensor. Waiting for it to arrived and i’ll let you how it goes!
Old 09-13-2020, 08:14 AM
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Originally Posted by S_F_Taylor
I've never known of a cranskshaft position sensor to fail on a 300SL or 500SL.

You're supposed to read codes for the ignition system with the engine running. Otherwise, one consequence is that code 17 will unconditionally appear. Find more info here.
hello S_F_Taylor, i havent read the codes with the engine running however i check the crankshaft position sensor with a multimeter and my reading was around 1000 ohms when hot and around 900ohms when the engine was cold in the morning. I have read that the sensor to be good the reading should be around 550-750 ohms
Old 09-13-2020, 08:27 AM
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@MikeShields @Mike00135 I would throw new sensors at it, starting with the crankshaft position sensor. It's a 30 year old vehicle. Nothing, including sensors, lasts forever.
Old 09-13-2020, 08:34 AM
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Originally Posted by chassis
@MikeShields @Mike00135 I would throw new sensors at it, starting with the crankshaft position sensor. It's a 30 year old vehicle. Nothing, including sensors, lasts forever.
@chassis ordered one waiting for it to arrive.. hoping it will arrive soon and solve the issue!
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Old 09-14-2020, 01:23 AM
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Originally Posted by S_F_Taylor
You've been misled once, and with advice to replace a perfectly-working sensor you are being misled a second time. Any resistance between 650 and 1200 ohms is fine. If it ain't broken, don't fix it!
thanks for the info... so lets take it from the beginning.. my ASR light is permanently on... the engine will not pass 5000rpm even with full pedal and the kick-down doesn't response as it should... acceleration of the car most of the time is too slow... You can feel the car shaking when in idle not too much but you feel it... of course no traction control... the car was in a storage for about 4-5 years... i have checked the asr pump under the fender and it works..

any suggestions?
thanks
Old 09-14-2020, 08:37 AM
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Originally Posted by S_F_Taylor
What model year is your car, Mike?
500SL 9/1990
Old 09-14-2020, 10:10 AM
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Originally Posted by S_F_Taylor
I'd check the fuel mixture. To do that you'll need a multimeter. With the engine idling at a temperature greater than 40 degrees C. you first measure the voltage between sockets #2 and #3 of the connector located on the passenger inner fender. That voltage should fluctuate several tenths of a volt and be roughly 30% - 70% of the steady voltage measured between sockets #2 and #6. Next you switch the engine off and again measure the voltage between sockets #2 and #3. Now it should be steady and be 70% of the voltage you measure between #2 and #6.
am not sure to which socket you are referring to.. is there a photo you can post so i can identify the socket?
appreciate your help.. thanks!
Old 09-29-2020, 04:45 AM
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Originally Posted by S_F_Taylor
I'd check the fuel mixture. To do that you'll need a multimeter. With the engine idling at a temperature greater than 40 degrees C. you first measure the voltage between sockets #2 and #3 of the connector located on the passenger inner fender. That voltage should fluctuate several tenths of a volt and be roughly 30% - 70% of the steady voltage measured between sockets #2 and #6. Next you switch the engine off and again measure the voltage between sockets #2 and #3. Now it should be steady and be 70% of the voltage you measure between #2 and #6.
Please let me know to which socket you are referring to. Thanks
Old 11-29-2020, 12:57 AM
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Old 11-29-2020, 01:36 AM
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HI,
looking for find location for my cranskshaft position sensor , its very hard to find location , be side i have problem my left side engine, AIR MASS sensor , replace twice, by any chance can help me , if you have access to startek, information on my R129 v12, will appreciate
Mike

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