FD. Checking the on-Board Diagnostics II (OBD II) Socket

FD. Checking the On-Board Diagnostics II (OBD II) socket
(Only certain markets, USA and Canada)

Fault-tracing information






OBD II is a diagnostics system designed to meet legal requirements. Instruments for fault-tracing can be plugged in to the OBD II socket in order to access DTCs and system parameters. OBD II contains emission DTCs and parameters.


Operating basics:

- DTCs absent
- The fault is permanent.


Defect cause:

- Short circuit to ground in the communication wiring.
- Break on communication, power ground, signal ground to supply wiring.

Fault-tracing starts with FD1.



FD1

Removing the OBD II socket






- Remove coin box.
- Release the OBD II socket.

Multimeter readings must be made from the rear of the OBD II socket.
Then continue with: Checking the power ground wiring FD2.



FD2

Checking the power ground wiring






- Ignition OFF
- Wait approx. 150 seconds.

Connect an ohmmeter between the OBD II socket terminal 4 and ground.
The ohmmeter should read approx. 0 Ohms

If reading is OK:
- Checking signal ground wiring FD3

If reading is incorrect:
- Check wiring between OBD II socket terminal 4 and ground point at the A-post on the passenger side (31/15) for breaks as per FA2. FA. Checking Wiring and Connections

Correct any fault found, then: Checking signal ground wiring FD3.



FD3

Checking signal ground wiring






- Ignition OFF

Connect an ohmmeter between the OBD II socket terminal 5 and ground.
The ohmmeter should read approx. 0 Ohms

If reading is OK:
- Checking supply wiring FD4.

If reading is incorrect:
- Check the cable between the OBD II socket terminal 5 and engine ground point 31/33 for breaks as per FA2. FA. Checking Wiring and Connections

- Correct any fault found, then: Checking supply wiring FD4.



FD4

Checking supply wiring






- Ignition OFF

Connect a voltmeter between the OBD II socket terminal 16 and ground.
The voltmeter should register battery voltage.

If reading is OK:
- Checking the OBD II communication wiring (ECM) FD7.

If reading is incorrect:
- Checking fuse 15 FD5.



FD5

Checking fuse 15






If the fuse is intact:
- Checking supply voltage (30 supply) before the fuse FD6.

If the fuse is defective:
- Check wiring for short-circuits to ground as per FA3. FA. Checking Wiring and Connections

Correct any fault found, then: Checking the OBD II communication wiring (ECM) FD7.



FD6

Checking supply voltage (30 supply) before the fuse






- Ignition OFF

Connect a voltmeter between the rear socket of the fuse holder to fuse 15 and ground.
The voltmeter should register battery voltage.






If reading is OK:
- Check the cable between fuse 15 and the OBD II socket terminal 16 for breaks in the circuit as per FA2. FA. Checking Wiring and Connections

Correct any fault found, then: Checking the OBD II communication wiring FD7.



If reading is incorrect:

- Check the cable between fuse 15 and the positive terminal on the battery for breaks as per FA2. Correct any fault found, then: Checking the OBD II communication wiring FD7.



FD7

Checking the OBD II communication wiring (ECM)






- Ignition OFF
- Disconnect the transmission control module (TCM) Connect an ohmmeter between the OBD II socket terminal 7 and ground.

The ohmmeter should read 90 - 110 k Ohms.

If reading is OK:
- Checking the OBD II communication wiring (ECM)

If the ohmmeter reads approx. 0 Ohms.
- Check wiring between OBD II socket terminal 7 and engine control module (ECM Motronic) #B36, and Data Link Connector (DLC) A terminal 6 and the transmission control module (TCM) #22 for short circuit to ground as per FD3.

Correct any fault found, then: Checking the OBD II communication wiring FD8.

If ohmmeter reads infinite resistance:
- Check the cable between the OBD II socket terminal 7 and ECM (Motronic) #B36 for breaks in the circuit as per FA2. FA. Checking Wiring and Connections

Correct any fault found, then: Checking the OBD II communication wiring (TCM) FD8.



FDB

Checking the OBD II communication wiring (TCM)







- Ignition OFF
- Connect the transmission control module (TCM)
- Disconnect the Engine Control Module (ECM)

Connect an ohmmeter between the OBD II socket terminal 7 and ground.

The ohmmeter should read 90 - 110 Ohms.

If reading is OK:
- OBD II socket is OK:

If reading is incorrect:
- Check the cable between OBD II socket terminal 7 and the TCM #B22 for breaks in the circuit as per FA2. FA. Checking Wiring and Connections