Isuzu 4JA1 Workshop Manual page 486

6E-232 Engine Control System (4JH1)
Step
2 1. Turn OFF the ignition.
2. Remove the thermo relay from the engine room
relay block.
3. Turn ON the ignition, with the engine OFF.
Does the A/C Request Signal parameter indicate
OFF?
3 1. Turn OFF the ignition.
2. Reinstall the thermo relay.
3. Remove the radiator grille in order to access the
pressure switch.
4. Disconnect
connector (C-24).
5. Turn OFF the blower motor switch.
6. Turn OFF the A/C switch.
7. Turn ON the ignition, with the engine OFF.
Does the A/C Request Signal parameter indicate
OFF?
4 Repair the short to battery or ignition voltage on the
thermo relay signal input circuit between the thermo
relay (pin 1 of X-15 connector) and the engine
control module (ECM) (pin 30 of C-56 connector).
Did you complete the repair?
5 Repair the short to ground between the thermo relay
(pin 5 of X-15 connector) and pressure switch (pin 1
of C-24 connector).
Did you complete the repair?
6 Repair the short to ground between the pressure
switch (pin 2 of C-24 connector) and the electronic
thermostat (pin 2 of C-55 connector), then electronic
thermostat (pin 1 of C-55 connector) and the A/C
switch (pin 5 of B-57 connector).
Did you complete the repair?
7 1. Test the A/C switch circuits shorted each other.
(pins 1 and 5 of B-57 connector).
2. Repair the circuits as necessary.
Did you find and correct the condition?
8 1. Test the circuit between the blower motor switch
(pin 1 of B-13 connector) and the A/C switch (pin
1 of B-57 connector) for a short to ground.
2. Repair the circuits as necessary.
Did you find and correct the condition?
9 Inspect the A/C (10A) fuse (EB-13) in the engine
room fuse block.
Is the A/C (10A) fuse (EB-13) open?
10 1. Replace the A/C (10A) fuse (EB-13). If the fuse
continues to open, repair the short to ground on
a circuit fed by the fuse or check for a shorted
attached component.
2. Repair the short to ground or replace the
component as necessary.
Did you complete the repair?
Action
the pressure switch
Value(s)
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harness
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Yes
Go to Step 3 Go to Step 4
Go to Step 6 Go to Step 5
Go to Step 39
Go to Step 39
Go to Step 39
Go to Step 39 Go to Step 36
Go to Step 39 Go to Step 37
Go to Step 10 Go to Step 11
Go to Step 39
No
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