OBDII Port Problems, No power on the K-Line

[406Grommit]

Hi guys,

I think i have a problem with my cars OBDII port as it has no voltage or any kind of reading on pin 7 (k-line). I only know there is surpose to be voltage of arround 3.5v on this pin from watching a youtube vid of someone checking the socket with a multimeter. The ground pins are working and i am getting the require 12v reading on pin 16 but no reading at all on pin 7.
As pin 7 is the ECU's communication line and is not working i cannot get any code readers to link with the ECU.

So far i have checked all fuses and am of the assumption that it is either a break in the wire, bad earthing or a faulty ECU not supplying the required voltage to pin 7. The only problem is im having trouble following the haynes manual electrical diagram. I have 3 plugs full of wires on my ECU but the haynes manual shows the ECU as 1 Block, not three sockets. Whats more is i cannot find any kind of numbering system on the plugs themselves so identifying what pin is what on the ECU plugs is my main concern.

Im hoping someone on here has possibly suffered from this problem before or has good enough electrical knowledge to help out a little.

Thanks

 

[HDi fun]

Try phoning Pug1Off in Brackley on 01280 701919 and speak to Matt Jobling.

 

[406Grommit]

Thanks i will give them a call

 

[pgarner]

hopefully you will have tried this but did you have the ignition on at the time ??

have you fitted an aftermarket stereo ?

 

[406Grommit]

Yes tried that and as far as i know the stereo is stock, however i cannot be sure as the stereo's anti theft audio alarm is present if i turn the radio on. I've not long had the car and the battery was disconnected when i got it so im assuming that's the reason for the stereos audio alarm.

I have also tried reading the k-line voltage with/without the stereo and with/without the engine turned on and according to this very handy vid i found i should have 3.5v on pin 7 (K Line) and that's the reason i cant get a reading from my diagnostic socket.

http://www.youtube.com/watch?v=0e-9_FuMWzI

 

[turbonutter69]

Yes tried that and as far as i know the stereo is stock, however i cannot be sure as the stereo's anti theft audio alarm is present if i turn the radio on. I've not long had the car and the battery was disconnected when i got it so im assuming that's the reason for the stereos audio alarm.

I have also tried reading the k-line voltage with/without the stereo and with/without the engine turned on and according to this very handy vid i found i should have 3.5v on pin 7 (K Line) and that's the reason i cant get a reading from my diagnostic socket.

http://www.youtube.com/watch?v=0e-9_FuMWzI

Alright buddy your post got caught up in the moderation queue as it contained a link and you are required to have 10 posts before you can upload pics and links.

 

[406Grommit]

Sorry about that, will read over the forum rules again:embarrest:

 

[HDi fun]

Sorry about that, will read over the forum rules again:embarrest:

BOunce a few posts off me and that'll get you up to 10 in no time.

The ODB2 in my 406 was always a bit flimsy - is yours the same as mine and mounted by driver's right knee right next to the cruise control master switch?

 

[406Grommit]

Cheers mate, Yes it is located next to the drivers right knee although i do not have cruise control lol

The no voltage on pin 7 can only be down to 1: A break in the wire 2: Faulty ECU and 3: A short somewhere but without knowing what pins on the ECU's relate to what wire's in the Haynes manual i cannot isolate the problem?

 

[turbonutter69]

Could it be a dodgy earth?

 

[HDi fun]

Cheers mate, Yes it is located next to the drivers right knee although i do not have cruise control lol

The no voltage on pin 7 can only be down to 1: A break in the wire 2: Faulty ECU and 3: A short somewhere but without knowing what pins on the ECU's relate to what wire's in the Haynes manual i cannot isolate the problem?

It does sound like it's a simple wiring fault. If the ECU itself was failing then you would have serious running problems and the display on the centre of the dashboard would be littered with warning messages.

 

[obi_waynne]

Is there an aftermarket radio fitted?

 

[406Grommit]

Could it be a dodgy earth?

If that is the case is it just a matter of cleaning up all the earth points and hoping my problem goes away or is there more to it?

 

[406Grommit]

It does sound like it's a simple wiring fault. If the ECU itself was failing then you would have serious running problems and the display on the centre of the dashboard would be littered with warning messages.

Maybe not the ECU at fault then but without knowing what wire is what on the ECU plugs i dont know how to rectify the problem???

I tried a continuity test from pin 7 to a few of the suspected wires on the ECU's plug and ended up getting a reading from more that one of them so im confused as to what would be going on there???

 

[406Grommit]

Is there an aftermarket radio fitted?

This was answered in the above posts mate :blink1:

 

[turbonutter69]

If that is the case is it just a matter of cleaning up all the earth points and hoping my problem goes away or is there more to it?

Could well be or a broken wire somewhere.

 

[406Grommit]

Could well be or a broken wire somewhere.

I agree but i cannot workout how to trace it as i cannot match up the ECU Pins with the haynes diagram and a continuity test aint helping me as i get a reading from more than one wire on the ECU plugs.

Lets look at this logically for a second, Instead of me asking how to identify the ECU Pins hows a bout i ask what could be causing me to get a continuity reading from pin 7 on the diag socket to multiple wires on the ECU plug ?

If the answer is a bad earth point then could this be a break in the wire or more likely bad contact points?

 

[jarrus]

It would sound like that yeah...I would check around any grommets that the loom is going though, maybe it has shorted there,