Isuzu 4JA1 Workshop Manual page 443

Step
12 1. Turn OFF the ignition.
2. Connect a 3-amp fused jumper wire across the
APP sensor connector between pins 2 and 3 of
the E-22 connector.
3. Turn ON the ignition, with the engine OFF.
Does DTC P1120 (Symptom Code 1) set, but not
P1120 (Symptom Code E)?
13 1. Test the 5 volts reference circuit between the
engine control module (ECM) (pin 55 of C-56
connector) and the APP sensor (pin 3 of E-22
connector) for an open circuit or high resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
14 1. Test the signal circuit between the ECM (pin 35
of C-56 connector) and the APP sensor (pin 2 of
E-22 connector) for an open circuit or high
resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
15 1. Test the signal circuit between the ECM (pin 35
of C-56 connector) and the APP sensor (pin 2 of
E-22 connector) for the following conditions:
•
A short to ground
•
A short to the low reference circuit
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
16 1. Test the low reference circuit between the ECM
(pin 47 of C-56 connector) and the APP sensor
(pin 1 of E-22 connector) for high resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
17 1. Turn OFF the ignition.
2. Inspect for an
connections or
connector of the APP sensor (pin 1, 2 and 3 of E-
22 connector).
3. Repair the connection(s) as necessary.
Did you find and correct the condition?
18 1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect for an
connections on the APP sensor circuits at the
harness connector of the ECM (pins 35, 47 and
55 of C-56 connector) or the idle switch circuit at
the harness connector of the ECM (pin 69 of C-
56 connector).
4. Repair the connection(s) as necessary.
Did you find and correct the condition?
19 Replace the accelerator pedal position sensor. Refer
to Accelerator Pedal Position Sensor Replacement
in this section. (Idle switch is part of APP sensor)
Did you complete the replacement?
20 Important: Replacement
programmed.
Replace the ECM. Refer to Engine Control Module
(ECM) Replacement in this section.
Did you complete the replacement?
Action
intermittent and for poor
corrosion at the harness
intermittent and for poor
ECM must
Engine Control System (4JH1) 6E-189
Value(s)


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

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be
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Yes
Go to Step 15 Go to Step 14
Go to Step 21 Go to Step 18
Go to Step 21 Go to Step 18
Go to Step 21 Go to Step 16
Go to Step 21 Go to Step 17
Go to Step 21 Go to Step 19
Go to Step 21 Go to Step 20
Go to Step 21
Go to Step 21
No
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