(BF) Testing DLC and Control Module

BF. DLC and Control Module

If control module does not respond (flashing LED), the cause could be a fault in the control module or in the OBD. Fault tracing starts with BF1.


BF1. Testing Fuel System Diagnostics






Ignition on.
Check OBD in diagnostic test mode 1 on another electronic system, for example the fuel system in DLC A2.

If the system works:
Test the cable between DLC and control module BF4.

If system does not work:
Power supply test BF2.


BF2. Power Supply Test






Ignition off.
Separate data link connector (DLC).
Ignition on.
Using a voltmeter, measure between DLC connector terminal A4 and ground.
Voltmeter should display battery voltage.

If the reading is OK:
Test ground connection BF3.

If reading is not OK:
Check cable between DLC terminal A4 and battery for breaks, according to (Q) Other Electrical Fault Tracing



BF3: Testing Ground Connection






Ignition off.
Data link connector (DLC) disconnected.
Using an ohmmeter, measure resistance between terminal A8 on the DLC connector and ground. Ohmmeter should display about 0 ohm.

If reading is OK:
Test on-board diagnostic system.

If reading is not OK:
Check cable from DLC terminal A8 and ground for breaks, see fault Q.


BF4. Testing Cable Between Data Link Connector (DLC) and Control Module






Ignition on.
Using a voltmeter, measure between DLC terminal B2 and ground.
Voltmeter should display about 10 volts.

If reading is OK:
Test control module ground cable BF6.

If voltmeter displays about 0 volts:
Test DLC cable resistance to ground BF5.

If voltmeter displays battery voltage:
Test the cable between control module terminal 4B and DLC terminal B2 for short circuit to supply, according to QA4.


BF5. Testing Diagnostic Cable's Resistance To Ground






Ignition off.
Separate data link connector (DLC).
Using an ohmmeter, measure resistance between DLC terminal B2 and ground.

If ohmmeter shows infinite resistance:
Check the cable between control module socket terminal 48 and DLC terminal 82 for breaks, according to QA2.

If ohmmeter reads about 0 ohm:
Check the cable between control module socket terminal 4B and DLC terminal B2 for short circuit to ground, according to above view QA3.


BF6. Testing Control Module Ground Connection






Ignition off.
Disconnect control module.
Using an ohmmeter, measure resistance between control module socket terminal 38 and ground.
Ohmmeter should display about 0 ohm.

If reading is OK:
Test power supply to control module BF7.

If reading is not OK:
Check the cable between control module socket terminal 3B and ground for breaks, according to QA2.


BF7. Testing Power Supply To Control Module






Disconnect control module.
Ignition on.
Using a voltmeter, measure between control module socket terminal 38 and terminal 18.
Voltmeter should display battery voltage.

If reading is OK:
Try a new control module.

If reading is not OK:
Fuse test BF8.


BF8. Fuse Test






Check that fuse 19 in the central electronics module is not blown.

If fuse is not blown:
Check the cable between fuse 19 and control module for breaks, according to QA2.

If fuse is blown:
Check the cable between:
fuse 19 and control module terminal 1B
vacuum pump terminal 3 and control module terminal 7E

fuse 19 and switch terminal 2
switch terminal 1 and brake valve

automatic transmission: brake valve and control module terminal 9E
manual transmission: brake valve and clutch valve terminal 2
manual transmission: clutch valve and control module terminal 9E
switch terminal 3 and control module terminal 6E
switch terminal 4 and control module terminal 8E
switch terminal 5 and control module terminal 4E for short circuit to ground, according to QA3.