Isuzu 1999 RODEO Workshop Manual page 912

f Damaged harness – Inspect the wiring harness for
damage; shorts to ground, shorts to battery positive,
and open circuits.
f Restricted air intake system – Check for a possible
collapsed air intake duct, restricted air filter element, or
foreign objects blocking the air intake system.
f Throttle body – Check for objects blocking the IAC
passage or throttle bore, excessive deposits in the IAC
passage and on the IAC pintle, and excessive deposits
in the throttle bore and on the throttle plate.
DTC P0506 – Idle Control System RPM Lower Than Expected
Step
1 Was the "On–Board Diagnostic (OBD) System Check"
performed?
2 Are any other Diagnostic Trouble Codes set?
3 1. Start the engine.
2. Turn all accessories OFF (A/C, rear defroster, etc.)
3. Using a Tech 2, command RPM up to 1500, down to
500, and then up to 1500 while monitoring "Engine
Speed" on the Tech 2.
Does the "Engine Speed" remain within the specified
value of "Desired Idle" for each RPM command?
4 1. Disconnect the IAC.
2. Install IAC Noid Light J 37027A or equivalent.
3. With the engine running, command RPM up to
1500, down to 500, and then up to 1500 while
observing the noid light.
Does each noid light cycle red and green (never OFF)?
5 1. Check the following circuits for an open, short to
voltage, short to ground, or poor connection at the
PCM:
f
IAC "A" low
f
IAC "A" high
f
IAC "B" low
f
IAC "B" high
2. If a problem is found, repair as necessary.
Was a problem found?
6 Visually/physically inspect for the following conditions:
f
Throttle body tampering (adjustment screw plug
removed).
f
Restricted air intake system. Check for a possible
collapsed air intake duct, restricted air filter
element, or foreign objects blocking the air intake
system.
f
Throttle body. Check for objects blocking the IAC
passage or throttle bore, excessive deposits in
the IAC passage and on the IAC pintle, and
excessive deposits in the throttle bore and on the
throttle plate.
Do any of the above require a repair?
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
Action
f Large vacuum leak – Check for a condition that causes
a large vacuum leak, such as an incorrectly installed or
faulty PCV valve or brake booster hose disconnected.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the Diagnostic Trouble Code to
be set occurs. This may assist in diagnosing the
condition.
Value(s)
— Go to Step 2
Go to other
Diagnostic
Trouble Code
—
No trouble
found. Go to
Diagnostic
+/–50 RPM
— Go to Step 6
— Verify repair
appropriate
section for
on–vehicle
—
6E1–285
Yes No
Go to OBD
System
Check
first Go to Step 3
Aids Go to Step 4
Go to Step 5
Go to Step 8
Refer to
service
Go to Step 7