Isuzu 1999 RODEO Workshop Manual page 866

DTC P0404 EGR Circuit Range/Performance
Step
1 Was the "On–Board Diagnostic (OBD) System Check"
performed?
2 1. Turn the ignition switch ON, with the engine OFF.
2. Install a Tech 2.
3. Command the EGR valve to the specified values.
Does the Actual EGR Position follow the Desired EGR
Position?
3 1. Turn the ignition switch ON, with the engine OFF.
2. Disconnect the EGR valve electrical connector.
3. With a test light connected to B+, probe the ground
circuit to the EGR valve.
Does the light illuminate?
4 1. Connect the test light to ground.
2. Probe the EGR control circuit to the EGR valve.
3. Command the EGR valve to the specified values
using a Tech 2.
As the command is raised, does the test light glow
brighter, flash or maintain a steady glow?
5 Repair the open or poor connection in the EGR ground
circuit.
Is the action complete?
6 With the test light still connected to ground, probe the
signal circuit.
Is the action complete?
7 With the test light still connected to ground, again probe
the control circuit without commanding the EGR valve
with the Tech 2.
Does the test light illuminate?
8 Check the signal circuit for a short to voltage and repair
as necessary.
Was a repair necessary?
9 With a Digital Voltmeter (DVM) connected to ground,
probe the 5 V reference circuit.
Is the voltage measured near the specified value?
10 Check the control circuit for a short to voltage and
repair as necessary.
Was a repair necessary?
11 Connect the test light to B+ and again probe the control
circuit.
Does the light illuminate?
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
Action Value(s) Yes
— Go to Step 2
25%, 50%,
Go to Step
75%, 100% 19
— Go to Step 4
25%, 50%,
75%, 100% Go to Step 6
Go to Step
—
19
— Go to Step 8
Go to Step
—
10
Go to Step
—
19
Go to Step
5 V 13
Go to Step
—
19
Go to Step
— 15
6E1–239
No
Go to
Powertrain
OBD System
Check
Go to Step 3
Go to Step 5
Go to Step 7
—
Go to Step 9
Go to Step
11
Go to Step
12
Go to Step
14
Go to Step
12
Go to Step
16