[mikeak_2001]

Hi all,

Background:

Vehicle is an E90 320I Sep 2008

With the help of this forum I have been programming and diagnosing happily for the past 2 years. I have activated alarm beeps, digital speed display and things like that. No communication faults or anything of the sort.

Recently I have been having issues with a misfire, so again used my setup and performed some live data capture. No problems and came away with some pretty line graphs.

I've put the fault down to number 4 injector and ordered one.

For some reason I have lost all comms with the vehicle however the vehicle runs fine with no blown fuses and no signs of faulty equipment, the light on the OBD cable doesn't flash anymore when I connect it to the vehicle.


I have tested multiple leads, and none communicate.

Checked the lead on another vehicle and as soon as I plug in the light on the k+dcan cable starts to flash.

So what now:

I have done the usual, disconnected battery for half an hour (incase a module is hogging the comm lines), tried different cables, reinstalled windows and all the software etc but still no luck.

Stripped out all the panels in the foot well and started testing (I work for Volvo ) and here is what I have found.

Pin assignment: (see attachment)
1 -- ign live
4 -- chassis ground
5 -- signal ground
6 -- Can Hi
14 -- Can Lo
16 -- Batt positive

First of all I tested all the lives and i've got my ign 12 volt, got my batt 12 volt, tested the can hi and low and they are putting out 2.5 volts as per industry standard.

so on to the grounds, disconnected the battery to protect modules, checked resistance and i've got 7 ohms resistance on chassis ground and 10 ohms resistance on the signal ground.

This is not how I know grounds to work so my questions are:

Anyone seen this before?
Anyone know where the ground point is?

If I've gone a bit too far someone please shout at me lol.

Thanks All

[cn555ic]

What makes you think its the obd port...Did you check the configurations of the computer...The computer constantly gets updates on the web for software and these updates many times messes with the settings on the computer...I would check that first

[nate5ks]

Originally Posted by cn555ic

What makes you think its the obd port...Did you check the configurations of the computer...The computer constantly gets updates on the web for software and these updates many times messes with the settings on the computer...I would check that first

The light on the k+dcan should illuminate regardless of computer settings. It even lights up when it isn't connected to the computer. Since his isn't illuminating at all when plugged into this car I suspect an obd malfunction as well.

[mikeak_2001]

Thanks for the responses, I have tried the multiple leads I have in a bmw today and a volvo (same obd pinout) and the bmw I can communicate with and the volvo communicates to the point of the light flashing but of course I work for volvo and know the protocol is different.

as previously stated I have totally reinstalled, even windows itself, the only car it won't communicate with is mine.

[makkan00]

Have you installed any security alarm or any modification to engine which blocks the communication to Obd?

[mikeak_2001]

Nothing new installed, been checking the online BMW WDS and pins 4 and 5 go straight to an earth rail under the drivers carpet, time to check for water ingress I think, living in wales and all we've had since it last worked is heavy rain.

Either way there shouldn't be any resistance on 4 and 5 and I have around 2 ohms, working out the maths its about 2v drop leaving 10 for the obd lead.

Will update when and if I find anything. Time to strip some carpets out (in the rain) lol

[roadkillrob]

It looks like you might be in the UK - I thought BMW did an update in the UK due to the issue where cars were being broken into easily and they used the OBD port to quickly program a key to the car, then they start it up and drive away. The update only applied to right hand drive cars and did something to disable to the OBD port.

What about trying it with the engine running - any difference?

Rob

[mikeak_2001]

Hi Rob,

Your are right I am in the UK, I haven't had the update regarding theft via OBD, this is a weird case of everything was working, software, leads etc, started getting a misfire, read and cleared codes with INPA, misfire came back, read out some live data to make sure of the fault before buying parts.

SInce then its been realy horid weather, now lost comms. Confirmed my setup works on other vehicles with no problems, even wiped the laptop and reinstalled everything and tested setup again. Tried multiple leads, all no comms.

MIke.

[ZShan]

I have the exact same fault with my car also. did you find out the issue?

[Joe@TopGearSolutions]

Originally Posted by ZShan

I have the exact same fault with my car also. did you find out the issue?

I've recently discovered that a bad JBBF (junction box) also causes this same issue. Installed a used one, coded it, then all was well.