Volts Is The Iat Sensor Parameter More Than The Go To Diagnostic Specified Value? Go To Step 4 Aids; Turn Off The Ignition; Connect A Dmm Between The Signal Circuit; 4.8 Volts - Isuzu N 2008 Series Workshop Manual

1A-108 Engine Control System (4JJ1)
Step
Observe the Engine Coolant Temperature (ECT)
Sensor parameter with a scan tool.
3
Is the ECT Sensor parameter more than the
specified value?
1.

Turn OFF the ignition.

2. Disconnect
connector.
3.

Connect a DMM between the signal circuit

4
(pin 1 of E25) and a known good ground.
4.

Turn ON the ignition, with the engine OFF.

Is the DMM voltage more than the specified value?
Important: The ECT sensor may be damaged if
the sensor signal circuit is shorted to a voltage
source.
1. Test the signal circuit between the ECM (pin
5
84 of E12) and the ECT sensor (pin 1 of E25)
for a short to battery or ignition voltage.
2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?
Connect a 3-amp fused jumper wire between the
signal circuit and the low reference circuit (pins 1
and 2 of E25).
6
Is the ECT Sensor parameter less than the
specified value?
Connect a 3-amp fused jumper wire between the
signal circuit (pin 1 of E25) and a known good
ground.
7
Is the ECT Sensor parameter less than the
specified value?
1. Test the signal circuit between the ECM (pin
84 of E12) and the ECT sensor (pin 1 of E25)
for an open circuit or high resistance.
8
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Notice: The ECT 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
9
ECM (pin 109 of E12) and the ECT sensor
(pin 2 of E25) for an open circuit or high
resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
1. Test the signal circuit between the ECM (pin
84 of E12) and the ECT sensor (pin 1 of E25)
for a short to any 5 volts reference circuit.
10
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Action
the ECT sensor harness
Value(s) Yes

4.8 volts

Go to Step 4
5.5 volts
Go to Step 5
—
Go to Step 15
0.1 volts
Go to Step 10
0.1 volts
Go to Step 9
—
Go to Step 15
—
Go to Step 15
—
Go to Step 15
No
Go to Diagnostic
Aids
Go to Step 6
Go to Step 14
Go to Step 7
Go to Step 8
Go to Step 12
Go to Step 12
Go to Step 11