Incorrect readings from Duty Cycle - PeachParts Mercedes-Benz Forum

John5788 · #1 08-16-2007, 10:13 PM

so after replacing my MAS unit in my 1993 190E 2.6, i decided to start checking my duty cycle again to make sure everything is right. i reset the engine code I was getting from my X92 LED diagnostic (which was giving me 22 blinks meaning o2 heater wires were dead) and now it blinks once, which means no errors.

i read this link http://www.landiss.com/mixture.htm and hooked my multimeter up to my X11 diagnostic port and put the black lead into pin 2 and red lead into pin 3.

then I went to the x92 and tried to get the red LED to stay on, but never happened. i hold it for 4 seconds, let go and watch it blink once. I do it again and see it blink once more instead of staying on. so that was the first error i ran into.

second error is that with the key in the on position, but engine off, im getting a duty cycle of 49.9% and a voltage in the neighborhood of 6.03v. i should be getting 85% because my car is a california car, but that is not the case. anyone have ideas why this is happening?

mbdoc · #2 08-17-2007, 07:55 AM

Are you trying to do the blink codes with the engine running?

IF not that is the sequence that must be done on a Calif car (that year).

John5788 · #3 08-17-2007, 01:04 PM

no, this is all done with key on, engine off.

so I must be doing this with the engine on? i dont understand

mbdoc · #4 08-17-2007, 02:33 PM

To get the duty cycle to display start the car & then go thru the 3-4 seconds & watch blinks, if only one blink depress the button for 3-4 seconds untill 1 blink again.......if more than 1 blink, erase any codes by holding for 8 seconds

John5788 · #5 08-17-2007, 04:45 PM

so what youre saying is that the red light doesnt necessarily have to be on to be in test mode, as long as you (1) clear all the codes, (2) hold the button for 4 seconds, let it blink once, (3) repeat step 2.

ill check my duty cycle when i get home then..

by the way, i had left my battery unplugged overnight to fully reset the system, and the first thing I did after i hooked the battery up again, was put the key on, engine off and check the duty cycle in pin 3 on the x11.

i was getting a reading of 69.9%, pretty much 70%. but my car is a california car, so why am i getting 70% rather than 85%? is there a component thats in my car that could be from another state which is why its giving me 70% instead of 85%?

John5788 · #6 08-17-2007, 11:30 PM

alright I got home and turned the engine off, went inside to grab my multimeter and hooked it up to the X11.

reading with key on engine off was 49.9% again (wtf?). i did the procedure at the x92 and started up my engine. i let it idle for a little bit and all of a sudden the reading started fluctuating! it was fluctuating closely around 53% which should mean its ok right?