Isuzu 2008MY N Series Workshop Manual page 309

1A-306 Engine Control System (4HK1)
Step
1. Test the signal circuit between the ECM (pin
66 of J-14) and the idle up sensor (pin 2 of B-
87) for the following conditions:
• An open circuit
• A short to ground
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• A short to the low reference circuit
• High resistance
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Important: The idle up sensor may be damaged if
the sensor signal circuit is shorted to a voltage
source.
1. Test the signal circuit between the ECM (pin
66 of J-14) and the APP sensor (pin 2 of B-87)
for the following conditions:
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• A short to battery or ignition voltage
• A short to any 5 volts reference
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Notice: The idle up sensor shares the low
reference circuit with other sensors. A fault
condition in the low reference circuit may set DTCs
on sensors that share this circuit.
1. Test the low reference circuit between the
14
ECM (pin 41 of J-14) and the idle up sensor
(pin 1 of B-87) for an open circuit or high
resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
1. Inspect for an intermittent and for poor
connections at the harness connector of the
Idle up sensor (pins 1, 2 and 3 of B-87).
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2. Repair the connection(s) as necessary.
Did you find and correct the condition?
1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for poor
connections at the harness connector of the
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ECM (pins 41, 42 and 66 of J-14).
4. Repair the connection(s) as necessary.
Did you find and correct the condition?
Replace the Idle up sensor. Refer to Idle Up Sensor
in Section 1I Engine Speed Control System.
17
Did you complete the replacement?
Important:
programmed and learned.
18
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement?
Action
Replacement ECM
Value(s)
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must be
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Yes
Go to Step 19 Go to Step 16
Go to Step 19 Go to Step 18
Go to Step 19 Go to Step 16
Go to Step 19 Go to Step 17
Go to Step 19 Go to Step 18
Go to Step 19
Go to Step 19
No
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