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Discussion Starter · #1 ·
I need info regards the pin out on the defender (td5)diagnostic socket I have built my own interface for the OBD2 iso 9141/14230 protocol working fine connected to the pc however the L line is stated in the protocol documentation as pin 15 on the diagnostic socket
On my 2002 MY Defender the connector has no pin on 15 but has a pin on pin 8 which aint any standard Ive seen. The additional problem is that there are 3 ECU's on 2 pins (7 & 8)1 for engine management 1 for the ABS and 1 for the 10as alarm imobelizer(sp?) etc
So I am presuming because the alarm ECU is on pin 8 that this aint the replacement L line instead of 15 and it almost suggests that its 2 K lines on pin 7 and 8 so a single K Line interface is required.
However not that I can explain easily in this email but i have had my interface connected and the experiments I have tried doesnt give me a warm feeling that my second theory is right either.

email me at [email protected]

238 Posts

Hi I looked in to this a while ago, Let me know how you go I would be interested in what you used to buid you interface.
Here is the small amount of info and you may have already seem this.

Standard for ODB
Pin 2 - J1850 Bus+
Pin 4 - Chassis Ground
Pin 5 - Signal Ground
Pin 6 - CAN High (J-2284)
Pin 7 - ISO 9141-2 K Line
Pin 10 - J1850 Bus
Pin 14 - CAN Low (J-2284)
Pin 15 - ISO 9141-2 L Line
Pin 16 - Battery Power

Land rover
also the standard for landrover is J 1962, Not sue if this makes a difference.
Pin 4 Grd
Pin 5 Grd
pin 7 ECU
pin 8 Alarm
pin 16 +12v

The primary form of communication is with the single-ended K-Line. The K-Line passes data bidirectionally, as well as transferring all address information during initialization. The K-line is pulled up to Vbat by a 510 ohms biasing resistor, and biased to ground through a resistor that may vary between 50K and 110K ohms [M].


The optional L-Line is unidirectional and is only used to pass address information from the diagnostic tester to the ECUs during initialization. The L-Line is in a 1-state during all other events. The K-Line will mimic the L-Line’s address initialization.

The L line seems not to be used on some later modled cars.

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