QuestionCheck engine light came on. I did the code check thing and it comes up 505 which is an Idle issue. The Van runs fine. How do I fix idle issue so light goes out?
AnswerWhen Monitored and Set Condition:
P0505-IDLE AIR CONTROL MOTOR CIRCUITS
When Monitored: At power-up and battery voltage greater than 11.5 volts.
Set Condition: The PCM senses a short to ground or battery voltage on any of the four
Idle Air Control (IAC) driver circuits for 100 msec while the IAC motor is active.
POSSIBLE CAUSES
IAC MOTOR WIRING HARNESS OBSERVABLE
IAC MOTOR WIRING HARNESS INTERMITTENT
IAC #1 DRIVER CIRCUIT SHORTED TO #2, #3, OR #4
IAC #2 DRIVER CIRCUIT SHORTED TO #3 OR #4
IAC #3 DRIVER CIRCUIT SHORTED TO #4
IAC MOTOR
IAC #1 DRIVER CIRCUIT SHORTED TO GROUND
IAC #2 DRIVER CIRCUIT SHORTED TO GROUND
IAC #3 DRIVER CIRCUIT SHORTED TO GROUND
IAC #4 DRIVER CIRCUIT SHORTED TO GROUND
IAC #1 DRIVER CIRCUIT OPEN
IAC #2 DRIVER CIRCUIT OPEN
IAC #3 DRIVER CIRCUIT OPEN
IAC #4 DRIVER CIRCUIT OPEN
POWERTRAIN CONTROL MODULE (IAC #1 DRIVER)
POWERTRAIN CONTROL MODULE (IAC #2 DRIVER)
POWERTRAIN CONTROL MODULE (IAC #3 DRIVER)
POWERTRAIN CONTROL MODULE (IAC #4 DRIVER)
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, read the DTC’s.
Is the Good Trip Counter displayed and equal to zero for P0505?
All
Yes ® Go To 2
No ® Go To 22
149
DRIVEABILITY - GAS
TEST ACTION APPLICABILITY
2 Start the engine and let idle.
Disconnect the IAC Motor harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the voltage of the IAC #1 Driver Circuit.
Was the voltage over 5.0 volts at any time?
All
Yes ® Go To 3
No ® Go To 19
3 Start the engine. Allow the engine to idle.
Disconnect the IAC Motor harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the voltage of the IAC #2 Driver Circuit.
Was the voltage over 5.0 volts at any time?
All
Yes ® Go To 4
No ® Go To 16
4 Start the engine. Allow the engine to idle.
Disconnect the IAC Motor harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the voltage of the IAC #3 Driver Circuit.
Was the voltage over 5.0 volts at any time?
All
Yes ® Go To 5
No ® Go To 13
5 Start the engine. Allow the engine to idle.
Disconnect the IAC Motor harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the voltage of the IAC #4 Driver Circuit.
Was the voltage over 5.0 volts at any time?
All
Yes ® Go To 6
No ® Go To 10
6 Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Note: The following steps are checking for a short between the IAC Driver
Circuits.
Measure the resistance between the IAC #1 Driver circuit and #2, #3, #4 Driver
circuits.
Is the resistance below 5.0 ohms on any of the Drivers?
All
Yes ® Repair the IAC Driver Circuits shorted together.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ® Go To 7
150
DRIVEABILITY - GAS
P0505-IDLE AIR CONTROL MOTOR CIRCUITS — Continued
TEST ACTION APPLICABILITY
7 Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Note: The following steps are checking for a short between the IAC Driver
Circuits.
Measure the resistance between the IAC #2 Driver circuit and #3, #4 Driver circuits.
Is the resistance below 5.0 ohms on any of the Drivers?
All
Yes ® Repair the IAC Driver Circuits shorted together.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ® Go To 8
8 Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Note: The following steps are checking for a short between the Driver
Circuits.
Measure the resistance between the IAC #3 Driver circuit and #4 Driver circuit.
Is the resistance below 5.0 ohms?
All
Yes ® Repair the IAC Driver Circuits shorted together.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ® Go To 9
9 If there are no possible causes remaining, view repair. All
Repair
Replace the Idle Air Control Motor.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
10 Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the IAC #4 Driver Circuit from the IAC Motor harness
connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
All
Yes ® Go To 11
No ® Repair the IAC Driver Circuit for an open.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
11 Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between IAC Driver #3 and ground (B-).
Is the resistance below 5.0 ohms?
All
Yes ® Repair the IAC #4 Driver Circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ® Go To 12
151
DRIVEABILITY - GAS
P0505-IDLE AIR CONTROL MOTOR CIRCUITS — Continued
TEST ACTION APPLICABILITY
12 If there are no possible causes remaining, view repair. All
Repair
Replace and program the Powertrain Control Module in accordance
with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
13 Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between IAC Driver #3 and ground (B-).
Is the resistance below 5.0 ohms?
All
Yes ® Repair the IAC #3 Driver Circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ® Go To 14
14 Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the IAC #3 Driver Circuit from the IAC Motor harness
connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
All
Yes ® Go To 15
No ® Repair the IAC Driver Circuit for an open.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
15 If there are no possible causes remaining, view repair. All
Repair
Replace and program the Powertrain Control Module in accordance
with the Service Information..
Perform POWERTRAIN VERIFICATION TEST VER - 5.
16 Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between IAC #2 Driver circuit and ground (B-).
Is the resistance below 5.0 ohms?
All
Yes ® Repair the IAC #2 Driver Circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ® Go To 17
152
DRIVEABILITY - GAS
P0505-IDLE AIR CONTROL MOTOR CIRCUITS — Continued
TEST ACTION APPLICABILITY
17 Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the IAC #2 Driver Circuit from the IAC Motor harness
connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
All
Yes ® Go To 18
No ® Repair the IAC Driver Circuit for an open.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
18 If there are no possible causes remaining, view repair. All
Repair
Replace and program the Powertrain Control Module in accordance
with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
19 Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between IAC #1 Driver circuit and ground (B-).
Is the resistance below 5.0 ohms?
All
Yes ® Repair the IAC #1 Driver Circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ® Go To 20
20 Turn the ignition off.
Disconnect the IAC Motor harness connector.
Disconnect the PCM harness connector(s).
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the IAC #1 Driver Circuit from the IAC Motor Connector
to the PCM Connector.
Is the resistance below 5.0 ohms?
All
Yes ® Go To 21
No ® Repair the IAC Driver Circuit for an open.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
21 If there are no possible causes remaining, view repair. All
Repair
Replace and program the Powertrain Control Module in accordance
with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
153
DRIVEABILITY - GAS
P0505-IDLE AIR CONTROL MOTOR CIRCUITS — Continued
TEST ACTION APPLICABILITY
22 Start the engine.
With the DRBIIIt in Systems Test, perform the IAC Wiggle Test.
Note: The idle speed should raise and lower with the display.
Wiggle the Wiring Harness from the IAC Motor to the PCM.
Observe for the IAC Motor to stop operating.
Did the IAC Motor stop operating at any time?
All
Yes ® Repair the Harness or Connectors as necessary.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ® Go To 23
23 Turn the ignition off.
Inspect the IAC Wiring and Connectors from the IAC motor to the PCM.
Were any problems found?
All
Yes ® Repair as necessary.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ® Test Complete.
