Isuzu 2008MY N Series Workshop Manual page 313

1A-310 Engine Control System (4HK1)
Step
Notice: If no ABS is installed, skip to Step 13.
1. Turn OFF the ignition.
2. Reconnect the EHCU harness connector.
3. Turn ON the ignition, with the engine OFF.
4. Connect a DMM between the CAN Low circuit
12
(pin 14 of B-105) and a known good ground.
5. Connect a DMM between the CAN High circuit
(pin 13 of B-105) and a known good ground.
Are both voltage readings within the specified
value?
Notice: If no Smoother is installed, skip to Step 14.
1. Turn OFF the ignition.
2. Reconnect the TCM harness connectors.
3. Turn ON the ignition, with the engine OFF.
4. Connect a DMM between the CAN Low circuit
13
(pin 14 of B-105) and a known good ground.
5. Connect a DMM between the CAN High circuit
(pin 13 of B-105) and a known good ground.
Are both voltage readings within the specified
value?
1. Turn OFF the ignition.
2. Reconnect
connectors.
3. Turn ON the ignition, with the engine OFF.
4. Connect a DMM between the CAN Low circuit
14
(pin 14 of B-105) and a known good ground.
5. Connect a DMM between the CAN High circuit
(pin 13 of B-105) and a known good ground.
Are both voltage readings within the specified
value?
1. Turn OFF the ignition.
2. Reconnect the VNT control module harness
connector.
3. Turn ON the ignition, with the engine OFF.
4. Connect a DMM between the CAN Low circuit
15
(pin 14 of B-105) and a known good ground.
5. Connect a DMM between the CAN High circuit
(pin 13 of B-105) and a known good ground.
Are both voltage readings within the specified
value?
1. Turn OFF the ignition.
2. Reconnect the ECM harness connectors.
3. Turn ON the ignition, with the engine OFF.
4. Connect a DMM between the CAN Low circuit
(pin 14 of B-105) and a known good ground.
16
5. Connect a DMM between the CAN High circuit
(pin 13 of B-105) and a known good ground.
Are both voltage readings within the specified
value?
Action
the DRM or BCM
Value(s)
1.5 to 3.5
volts
1.5 to 3.5
volts
harness
1.5 to 3.5
volts
1.5 to 3.5
volts
1.5 to 3.5
volts
Yes
Go to Step 13
Go to Step 14
Go to Step 15
Go to Step 16
Go to Diagnostic
Aids
No
Go to Step 20
Go to Step 22
Go to Step 21
Go to Step 19
Go to Step 18