Forums » Technical Help for Rover 75 and MG ZT » 75 and ZT Technical help for all derivatives » OBD plug

OBD plug by Fille


Fille
My Rover sailed through its MOT test today, no problems except that, once again, the tester couldn't get the OBD (On Board Diagnostics) system to talk with his computer. This has happened a couple of times before and usually just prodding around with the connector has cured the probelm. Not now though.
He passed the car anyway because emissions were fine and there were no warning lights on but suggested I get the plug checked. Does that mean a new LSM (Light Switch Module) or...?
2001 Rover 75 Tourer Connoisseur A - 1990 Citroën XM - 2005 Citroën C3 - 1973 Morris Marina 1,3 Coupé - 1973 Morris Marina 1,8 TC Coupé - 1986 Honda Civic (Rover 216 ;))

Posted 31 Aug 2010, 18:53 #1 

User avatar
raistlin
I wasn't aware that OBD access was an MOT fail point? :confused:
Paul

Cogito ergo sum... maybe?

Click the image to go to Nano-Meet Website
Image

Posted 31 Aug 2010, 19:14 #2 

User avatar
Duncan
Don't think Fille means the UK MOT.

Anyhow: could be power to the plug, or just a loose pin. The connection for OBD is direct to each unit, so changing the LSM won't help.
Image

Posted 31 Aug 2010, 20:11 #3 

User avatar
raistlin
Duncan wrote:Don't think Fille means the UK MOT.


:gmc:
Paul

Cogito ergo sum... maybe?

Click the image to go to Nano-Meet Website
Image

Posted 31 Aug 2010, 20:34 #4 


Fille
It didn't fail on this, actually it didn't fail at all, not even advisories, but the tester couldn't get his machine to talk with my car. In Finland all cars made after 2001 are OBD-tested when they have their yearly equivalent to your MOT test.
I just thought the LSM had the OBD plug integrated to it because they are situated next to each other. But OK, will get the plug checked at its next service, probably next year before its next test ;)
2001 Rover 75 Tourer Connoisseur A - 1990 Citroën XM - 2005 Citroën C3 - 1973 Morris Marina 1,3 Coupé - 1973 Morris Marina 1,8 TC Coupé - 1986 Honda Civic (Rover 216 ;))

Posted 01 Sep 2010, 07:24 #5 

User avatar
Duncan
You are right they are close, but it's definintely a separate thing.

The plug has a number of connections but the imprtant ones for OBD are power and ground, plus K line. The K line goes to a few units including the engine and ABS (Antilock Braking System). If the power and ground are missing, the K line is disconnected or shorted to ground then communications won't work. Start by checking the security of the pins in the connector.
Image

Posted 01 Sep 2010, 19:21 #6 

Post a reply »

Top