Isuzu 4HL1 Workshop Manual page 163

Step
Check the clutch switch circuit for open wiring.
1. Starter switch "OFF", and disconnect the
VIM.
2. Disconnect the clutch switch connector
and jumper it.
6
3. Starter switch "ON".
4. Measure
connector pin and ground (e.g., frame or
body)
Was the voltage within range?
Check the fuse side harness of the clutch
switch circuit for open wiring.
1. Remove the jumper wire from the clutch
switch.
2. Starter switch "ON".
7
3. Measure the voltage between clutch
switch connector pin and ground (e.g.,
frame or body)
Was the voltage within range?
Check the VIM side harness of the clutch
switch circuit for open wiring.
1. Starter switch "OFF".
2. Jumper the starter switch connector and
8
measure the resistance at the VIM
connector.
Was the resistance within range?
Check the clutch switch circuit for +B short.
1. Starter switch "OFF".
2. Disconnect the VIM.
9
3. At the VIM connector pins, measure the
resistance.
Was the resistance within range?
Check the clutch switch circuit for short.
1. Starter switch "OFF", and disconnect the
VIM.
2. Disconnect the clutch switch connector.
3. Starter switch "ON".
10
4. Measure
connector pin and ground (such as frame
or body)
Was the voltage within range?
Replace the clutch switch.
11
Is the action complete?
Repair or replace the faulty harness.
12
Is the action complete?
Action
the voltage between
the voltage between
Value(s)
Pins 49-
ground: 24 V
VIM
Pins 1-
ground: 24 V
Pins 49-
ground
(jumpered:
pins 2-
ground): 0 Ω
Pins 49-36/
38/75/76: ∞ Ω
Pins 49-
ground: 0 V
VIM
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Engine Control System 1A-161
Yes
Go to Step 11
Go to Step 8
Go to Step 4
Go to Step 10
Go to Step 11
Verify repair and
go to Step 15
Verify repair and
go to Step 15
No
Go to Step 7
Go to Step 12
Go to Step 12
Go to Step 12
Go to Step 12
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