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high voltage on OBD pin 7

Posted: Wed Nov 20, 2013 11:52 am
by biggeek
Hello

Coming out from lurking in the shadows again. :)

I am having troubles get my obd readers to work.

my bmw scanner stopped working and my C100 read some information but not the modules I need EHC...yes my air suspension is still playing up...sigh..i have elm module and all scanner work on other cars so it is my car with the issue.

I check the voltage of the pins using a multimeter and get 9+ volts on pin 7 ..K-line I believe which does not seem to be right. I have pulled all but the high volt fuses in glove box and read cabin but still cant find the fault.

I turned on everything an let the battery drained down until the volts where under 6 and I could read more modules....ehc still was quite working but I am convinced this is due to overvolatge on the line. My battery went dead for the first time a few weeks ago( I rearly drive the car) so I got an s5 and ctek charger

I know I have had my sat/nav reset itself and my main screen sometime reboot, I have seen an ac fault and my panoramic sunroof broke in the usual way(rear panel stayed up) I concentrated on all of those fuses especially however I have only been pulling fuses one at a time where as I know several system, radio,ehc..etc uses multiple fuses...I will try pulling multiple related fuses this weekend but I was just wondering if anybody had any ideas?

Thank in advance

Re: high voltage on OBD pin 7

Posted: Wed Nov 20, 2013 1:37 pm
by Steamyrotter
My first (and the annoying) suggestion..
disconnect battery for 5-10 mins and short leads to discharge car..
reconnect and try again...

Some modules do not like low voltages and lock up certain parts of the comms systems..
The above reboot proceedure may be all you need

Regards

Re: high voltage on OBD pin 7

Posted: Wed Nov 20, 2013 3:22 pm
by biggeek
Thanks but I have tried for about 30 mins with no joy.

I also need to try the disconnect discharge and leave over night trick too.

Re: high voltage on OBD pin 7

Posted: Thu Nov 21, 2013 6:33 pm
by Steamyrotter
Ah...

Unfortunately then you will have to do a process of elimination and unplug various modules until the port plays properly.
One must be bringing the voltage up somewhere..

I used to have a diagram of the bus structure in the majority of BMWs which may help pinning it down...
Will try to find it...

Update
Here it is.
Might give you some pointers on what to unplug and which bus they are on.

Image