I made this yesterday (Sunday) to check for malfunction codes for the ACC II in my '95 E300. No malfunction codes (one flash) but the LED would glow dimly when it was supposed to be off. I'm wondering if the PBU ground is weak/corroded?
The diagnostic system works by grounding the appropriate pin in the diagnostic connector (pin 7 in this case) in impulses to output the code. This crude counter applies battery voltage to an LED that is connected to the test pin, so the LED lights each time the diagnostic system grounds the pin. Count the flashes, and you have the code that you can look up in the FSM. Pressing and holding the button also grounds the test pin; ground it for 2-4 seconds to get the first code, and repeat to get any additional codes. Hold for 8 seconds or more to clear the codes. Attached is a schematic I found on peach parts, which lists the radio shack part numbers. I substituted almost all, including a combination LED / resistor set up for 12 vdc. Probably about $20 in parts plus an empty pill container. The container fits in you hand nicely so the button can be operated with your thumb. I need to put some labels on the wires (Battery, Ground, & Test). I should have dug through my parts bin, I've got some stuff that would have worked fine, but would not have made a nice neat package like this. Max Dillon, Charleston -------------- next part -------------- A non-text attachment was scrubbed... Name: 10425d1060094804-reading-codes-mb_tst3.jpg Type: image/jpeg Size: 16664 bytes Desc: not available URL: <http://mail.okiebenz.com/pipermail/mercedes_okiebenz.com/attachments/20140811/d04493f8/attachment.jpg> -------------- next part -------------- A non-text attachment was scrubbed... Name: IMG_20140810_194932_747.jpg Type: image/jpeg Size: 644762 bytes Desc: not available URL: <http://mail.okiebenz.com/pipermail/mercedes_okiebenz.com/attachments/20140811/d04493f8/attachment-0001.jpg> _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
