Fault Codes for 260E 1987? - PeachParts Mercedes-Benz Forum

andrew1413 · #1 06-29-2004, 08:12 PM

Where can I find fault codes for 260E 1987?
Tnx.

mbdoc · #2 06-30-2004, 07:59 AM

That system doesn't have any ability to store fault codes. The only thing you can check is whether or not the duty cycle can be read at the diagnostic connector.

ctaylor738 · #3 06-30-2004, 08:56 AM

If you have a problem that the ECU can diagnose, you will get a constant on/off ratio from Pin 3. It is in even percents (10, 20, .... 90). If you get the reading, I can look up what it indicates on the CD.

andrew1413 · #4 06-30-2004, 10:12 AM

I have constant light ON on the pin 3 - no flashing. What does it mean?
Tnx.

ctaylor738 · #5 06-30-2004, 11:47 AM

Nothing. On these cars you need to measure the on/off ratio (percentage) with a DMM with a duty cycle function.

You can also measure the battery voltage (V1) with the car idling, then measure the voltage between Pin 3 and ground (V2) and calculate V2/V1 as a percentage.

Ideally, the voltage will fluctuate around 50% battery voltage.

autozen · #6 06-30-2004, 05:55 PM

Chuck,
Splain that V1 V2 thing to me. I've never heard of that. Sounds interesting. Would that ratio work to read a fault code?

Peter

ctaylor738 · #7 06-30-2004, 10:50 PM

OK, but with all disclaimers about not being an authority.

The ECU is sending on/off signals to the frequency valve or EHA. These can be measured by duty cycle at Pin 3 as a %, or as DC voltage representing a % of battery voltage at Pin 3. Or as current at the EHA, I believe.

So, you measure battery voltage, V1, with the engine idling and say you get 13.5V. Then you measure Pin 3 to ground, V2, and get a reading bouncing around 6.25V. V2/V1 x 100 = 50%.

I am not making this up.

autozen · #8 06-30-2004, 11:28 PM

Thanks Chuck. I'll check it out.

Peter

87-300E_in_NC · #9 07-01-2004, 02:02 AM

Greetings all....I am glad to hear your comments MB Doc about the inability of storing fault codes on these cars, since somewhere in the archives on this forum I read the opposite.

I have an 87 260E that was flooding severely before I changed out the idle/air control valve bolted on the intake. If it will only idle like it should, it will be drivable once again.

My duty cycle readings are ranging from 30% to 40% (after warmed up) with high idle and reasonable exhaust emmissions (not smoky or cloudy at night with car lights shinning behind the car)...but with a 1200 rpm idle. I unplugged the TPS and idle increased. Maybe an 80mph roadtrip would help, with injector cleaner, as rust did slow me down a bit in the last fuel distributor...(yes I cleaned the injectors, but I'm not ruling them out as the cause for fast idle).

Thanks to ctaylor738 for the help also, and to Andrew for starting this thread, as I was about to ask the exact same question. Life happens, huh? Thanks also to P. S. for all the confidence and assistance during my most trying times dealing with my Benz!

andrew1413 · #10 07-01-2004, 11:29 AM

The diagnostic 9-pin connector in 1987 260E - what else can it be use for?
I read about pin 3 but what about 8 others?

autozen · #11 07-01-2004, 06:42 PM

Chuck,

i know you are not making this up and i'm trying to follow you. You don't have to be an authority. Bucky Fuller, the inventor of the geodesic dome once said; " ideas are out there floating around for someone to get them". I was an electronics technician 30 years ago and used lab scopes way before they became popular in the automotive field, but that was 30 years ago. Hopefully I still understand some of the rules of electron theory. Are you measuring this voltage on the DC scale or the AC scale? It sounds like you are coming up with a peak to peak or root means square AC reading. I appreciate your input, Chuck. You have always been a great help to people on this site.

Thanks,
Peter