ODB 1 code reader
 

My '89 560SL has what I assume is the first attempt at an OBD system. Not sure if the correct term is OBD 1 or maybe OBD 0, but it has a nine pin connector under the hood. Where can I buy one or can one be built easily? Also it would be nice to have a listing of what the blink codes each mean.

Thanks.

The Baum book has a little info on the 9 pin on page 13. I think your car suffers a bit from being at the end of such a long production run - almost 2 decades.

http://www.geocities.com/MotorCity/Downs/1039/mercedes/cs1000_mb.pdf

Good lead - thanks. I'm seeing what's out there.

The 9 pin connector has codes , but they are not flash format, they are in duty% values..Sears has a DMM that reads duty cycle for approx $20....

Thanks Arthur - I never knew that. That's a start. I need to get myself a multimeter that reads duty cycles. I saw the ones at Sears you were talking about. Is there such a thing as a manual that is Mercedes specific that will help me interpret the codes?

The duty cycle used by MB is actually the %off time, so read the duty dycle and subtract it from '1'.

Read the duty cycle and post it here. Read it at pins 2 and 3, pin 3 being ground.


http://i19.photobucket.com/albums/b1...DSC_0037-1.jpg

Thanks guys - found out from my son that a dwell meter reads duty cycles. It just needs to be converted to 100. So I read mine the other day and here's what I got. These numbers are converted and then subtracted from 100.

Used pin #3 as the ground.

With the engine off and key in the off position, only pin #6 gave any kind of reading and it was 1.00. So I assume that means pin #6 is the only one that is hot all the time.

With the engine idling I got the following:
Pin #1 - 42 - 51
Pin#2 - nothing
Pin#3 - N/A - used as the ground
Pin#4 - 51 - 60
Pin#5 - 36 - 45
Pin #6 - 36 - 45
Pins 7 - 9 - nothing

I did not take any readings with the engine off and the key in the on position.

So what does this tell me? Is there anyway any of these numbers help me with my SRS light on issue?

Thanks.