Question about 2004 Jeep Grand Cherokee

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Error code P0505 and rough idle with surge

Is there a way to teel for sure if it is an IAC motor or the powertrain control module?

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  • paulb4440 Jan 08, 2009

    check engine light on checked p0505 replaced iac cleaned throttlebody erased the code engine idles 1500 rpm light still on any help?

  • bosoxal00 Feb 16, 2009

    check engine light on code p505



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The code you have is difinitely idle air control motor. I guess you could check continuity and compare to a known good unit, but this test may not be valid. Before condemming it though, make sure "business end" is clean and free of carbon or varnish. That applies to passage into plenum as well. If everything is clean then replace unit.

Posted on Jan 08, 2009

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Well usually when i scan out that code usually replace ICM idle sensor motor! you should have a hard time idle or really rough one for this to go good place to start

Posted on Jan 08, 2009


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Extracted from

Code P0507

Possible causes

- Dirty throttle body

- Electric throttle control actuator misadjusted or damaged

- Faulty Electric throttle control actuator

- Intake air leak

- Poor electrical connection to the Intake Air Control (IAC) valve

help.jpg What does this mean?

Tech notes

If there are no intake leaks, clean throttle body, adjust engine idle and erase engine code. If the code comes back you may have to replaced the Electric Throttle Control Actuator (Motor) to repair the problem.

There is a factory service bulletin for the following Chevrolet models:

2006-2008 Chevrolet Trail Blazer

2007-2008 Chevrolet Avalanche

2007-2008 Chevrolet Express

2007-2008 Chevrolet Silverado

2007-2008 Chevrolet Suburban

2007-2008 Chevrolet Tahoe

Chevrolet Factory Service Bulletin OBDII Code P0507

What does this mean?

When is the code detected?

Thi P0507 code sets when the Powertrain Control Module (PCM) detects an engine speed outside of the Idle Air Control (IAC) valve range of control.

Possible symptoms

- Engine Light ON (or Service Engine Soon Warning Light)

- Engine hard to start

- Rough or erratic idle speed

P0507 Chevrolet Description

The Idle Air Control (IAC) valve is a Powertrain Control Module (PCM) controlled stepper motor located on the throttle body. The stepper motor drives a valve pintle which protrudes into a passage that bypasses the throttle plates. The PCM commands the IAC valve pintle to extend to decrease the idle speed. The bypass air flow is reduced and the idle speed decreases as the pintle approaches its seat. The PCM retracts the IAC valve pintle away from its seat to increase the idle speed. The retracting of the IAC valve pintle allows more air to bypass the throttle plates. One of the PCMs uses for the IAC system is to maintain a desired idle speed. This DTC sets when the PCM detects an engine speed outside of the IAC\'s range of control.

Read more:

Jan 11, 2015 | 2001 Chevrolet Blazer

1 Answer

I just got my car scanned and a few codes pop up

Error Code: P0130
Oxygen Sensor (O2S) 1, Bank 1 - Circuit Malfunction
Possible Cause:
Malfunction Indicator Lamp (MIL) Triggered on first occurrence.
-Wiring harness.
-Oxygen sensor (O2S).
-Engine control module (ECM).

Error Code: P0505
Idle Speed Control (ISC) System - Malfunction
Possible Cause:
-Wiring harness.
-Idle speed control (ISC) actuator/Idle air control valve (IAC) valve.
-Throttle motor.
-Throttle valve tight/sticking.
-Engine control module (ECM).

Error Code: P0100
Fault Location:
-Mass Air Flow (MAF) Sensor/Volume Air Flow (VAF) Sensor - Circuit --Malfunction
Possible Cause:
-Wiring harness.
-Mass air flow (MAF) sensor.
-Volume air flow (VAF) sensor.
-Engine control module (ECM).

Error Code: P1491
Exhaust Gas Recirculation (EGR) Valve Insufficient Lift
Possible Cause:
-Wiring harness.
-EGR Valve.

Error Code:P1607
-Engine Control Module (ECM)/Powertrain Control Module (PCM)

Error Code: P0966
-Pressure Control (PC) Solenoid B - Circuit Low
Possible Cause:
-Wiring short to earth.
-Pressure control (PC) solenoid.
-Engine control module (ECM)/Powertrain control module -(PCM)/Transmission control module (TCM) .

Apr 30, 2013 | 2004 Honda Civic

1 Answer

94 nissan altima won't start and iddle after cleaning IACV valve

An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars computer or PCM (powertrain control module) receives information from various sensors and will output signals to adjust the idle air control motor in or out to adjust engine idle speed by controlling engine idle air. An idle air control motor can fail one of two ways, either the motor short circuits and stops working or the motor will develop high resistance and cause the idle air control motor to react slowly, either failure can cause the engine to stall at idle. When a trouble code scan is performed it sometimes won't always detect a failed or weak idle air control motor.

Oct 08, 2012 | Nissan Altima Cars & Trucks

1 Answer

I have a 1999 dodge caravan it idles very high and can't figure out how to idle it down

The idle speed is computer controlled. First look for a possible vacuum leak. If there's no vacuum leak, the problem could be the TPS (throttle position sensor), the IAC motor (idle air control) or the PCM (powertrain control module). You will most likely need a scanner to find the cause if it's not a vacuum leak.

Apr 17, 2011 | Dodge Caravan Cars & Trucks

1 Answer

1999 Ram 3500 Wagon with 5.9L has eng Lt on. Idles high at red lights & surges at times. Code scanned is P0505. Do I need idle control valve or computer to make control valve work properly.

The IAC stepper motor is mounted to the throttle body, and regulates the amount of air bypassing the control of the throttle plate. As engine loads and ambient temperatures change, engine rpm changes. A pintle on the IAC stepper motor protrudes into a passage in the throttle body, controlling air flow through the passage. The IAC is controlled by the Powertrain Control Module (PCM) to maintain the target engine idle speed.

At idle, engine speed can be increased by retracting the IAC motor pintle and allowing more air to
pass through the port, or it can be decreased by restricting the passage with the pintle and diminishing the amount of air bypassing the throttle plate.
The IAC is called a stepper motor because it is moved (rotated) in steps, or increments. Opening the IAC opens an air passage around the throttle blade which increases RPM.

The PCM uses the IAC motor to control idle speed (along with timing) and to reach a desired MAP during decel (keep engine from stalling).

The IAC motor has 4 wires with 4 circuits. Two of the wires are for 12 volts and ground to supply electrical current to the motor windings to operate the stepper motor in one direction. The other 2 wires are also for 12 volts and ground to supply electrical current to operate the stepper motor in the opposite direction. To make the IAC go in the opposite direction, the PCM just reverses polarity on both windings. If only 1 wire is open, the IAC can only be moved 1 step (increment) in either direction. To keep the IAC motor in position when no movement is needed, the PCM will energize both windings at the same time. This locks the IAC motor in place.

In the IAC motor system, the PCM will count every step that the motor is moved. This allows the
PCM to determine the motor pintle position. If the memory is cleared, the PCM no longer knows the position of the pintle. So at the first key ON, the PCM drives the IAC motor closed, regardless of where it was before. This zeros the counter. From this point the PCM will back out the IAC motor and keep track of its position again.

When engine rpm is above idle speed, the IAC is used for the following:
  • Off-idle dashpot (throttle blade will close quickly but idle speed will not stop quickly)
  • Deceleration air flow control
  • A/C compressor load control (also opens the passage slightly before the compressor is engaged so that the engine rpm does not dip down when the compressor engages)
  • Power steering load control
The PCM can control polarity of the circuit to control direction of the stepper motor.

  1. First, try removing the IAC Valve, and cleaning the valve and the opening in the throttle body where the IAC Valve installs using Carburetor Cleaner. Ensure that the IAC Valve hole in the throttle body is not clogged, and is free from carbon deposits, etc. Have the ECM reset and check for the problem again.
  2. If the Check Engine Light comes back on, replace the IAC Valve. Have the ECM reset and check for the problem again.
  3. If the Check Engine Light still comes on, although highly unlikely, you may have a clogged throttle body, faulty wiring or connector, or faulty ECM (very unlikely since the vehicle runs).

Apr 13, 2011 | 1999 Dodge Ram

1 Answer

I'm pulling a motor 3.0 v-6 2000 taurus is there a diagram to help me my concern is clearance at front of motor where pullys are

here are complete instructions from It doesn't show the clearance, but it does tell you what has to come off to clear.
  1. Disconnect the negative battery cable.
  2. Drain the engine oil.
  3. Drain the cooling system.
  4. Recover the A/C refrigerant.
  5. On the 3.0L (VIN S) engine, remove or disconnect the following:

    Windshield wipers Cowl extension Emission vacuum control connector at the right side of the dash panel Hood Steering column pinch bolt Mass Airflow (MAF) sensor connector Intake Air Temperature (IAT) sensor Air cleaner assembly Idle Air Control (IAC) valve connector Throttle Position (TP) sensor connector Fuel lines Intake manifold vacuum hoses Ground straps Powertrain Control Module (PCM) connector Engine control sensor wiring harness connectors from the bracket located at the top of the transaxle Evaporative emission canister purge valve connector Crankcase vent hose Accelerator cable Cruise control actuator Shift cable and lever Secondary air injection pump relay connector Main emission vacuum control connector near the fan shroud Radiator hoses Heater hoses Transaxle oil cooler lines Power steering return hose Alternator wiring harness connectors A/C compressor lines A/C pressure cutoff switch, if equipped Front wheels Stabilizer bar links Lower ball joints Outer tie rod ends Halfshafts Radiator splash shield Heated Oxygen (HO 2 S) sensors Dual converter Y-pipe Power steering pressure switch connector Power steering pressure hose
  6. Support the powertrain from below and remove the subframe bolts.

6c74736.gif Fig. Throttle and cruise control cables-2001-04 3.0L (VIN U) engine shown

1f3d2f9.gif Fig. Throttle Position (TP) sensor and Intake Air Control (IAC) valve connectors-2001-04 3.0L (VIN U) engine shown

1c8414a.gif Fig. Support the powertrain when removing the subframe bolts
  1. Raise the vehicle away from the powertrain.
  2. Attach an engine hoist to the powertrain.
  3. Remove the left, right, and rear powertrain support insulators and lift the powertrain away from the subframe.
  4. Support the transaxle from below.
  5. Remove or disconnect the following:

    Starter motor Torque converter Transaxle flange bolts
    Separate the engine from the transaxle.

Oct 13, 2010 | Ford Taurus Cars & Trucks

1 Answer

2005 F150 5.4 Cuts off when driving at constant speed and show "Engine Fail Safe Mode" on display. It will crank back up and run for several hundred miles before doing it again. P2112 Throttle Air...

unfortunately no ! Your best bet take it to the dealer . The P0420 always ends up being the catalytic converter ! P2104 isn't throttle air control . P2112 - Throttle Actuator Control (TAC) System - Stuck Closed. Description: This powertrain control module (PCM) fault status indicates the throttle plate is at a lower angle than commanded. Possible Causes:
  • Binding throttle body, stuck closed.
  • Damaged PCM.
Diagnostic Aids: Application Key On Engine Off Key On Engine Running Continuous Memory All GO to DV1
P2104 - Throttle Actuator Control (TAC) System - Forced Idle Description: The TAC system is in the failure mode effects management (FMEM) mode of forced idle. Possible Causes:
  • Open or short in multiple accelerator pedal position (APP) sensor circuits.
  • Damaged APP sensor.
  • Damaged powertrain control module (PCM).
Diagnostic Aids: This DTC is an informational DTC and can be set in combination with a number of other DTCs which are causing the FMEM. Diagnose other DTCs first. Application Key On Engine Off Key On Engine Running Continuous Memory All GO to QE1
P0506 - Idle Air Control (IAC) System RPM Lower Than Expected For Vehicles With Electronic Throttle Control (ETC) Description: This DTC is set when the powertrain control module (PCM) detects an engine idle speed that is less than the desired RPM. Possible Causes:
  • Air intake restriction.
  • Exhaust restriction.
  • Engine mechanical fault.
  • Damaged electronic throttle body (ETB).
  • Damaged PCM.
Diagnostic Aids: This DTC is informational only and it may be accompanied by other DTCs. Diagnose other DTCs first. If other DTCs are not present inspect the intake air system for air restrictions and damage. If no concerns are present, clear the DTC and retest. For All Others Description: This DTC is set when the powertrain control module (PCM) detects an engine idle speed that is less than the desired RPM. Possible Causes:
  • IAC circuit open.
  • Air inlet is plugged.
  • B+ or VPWR to IAC solenoid open.
  • Damaged or incorrect IAC valve.
  • IAC valve stuck closed.
  • VPWR to IAC solenoid open.
  • IAC circuit shorted to PWR.
Diagnostic Aids: Disconnect the IAC valve and look for little or no change in engine RPM as an indication of a stuck or damaged valve. Application Key On Engine Off Key On Engine Running Continuous Memory Vehicles With Electronic Throttle Control (ETC) Refer to the Description, Possible Causes and Diagnostic Aids for the DTC. All others GO to KE1

Jul 03, 2017 | 2005 Ford F-150

1 Answer

Engine light code P1507: ''manf cntrl veh spd idle speed control auxiliary inputs'' and P0306: ''cylinder 6 misfire detected''. this ranger resitates press gas. where do i start?

P1507 is "Idle Air Control System Underspeed Error". This code indicates a problem with the Idle Air Control (IAC) valve assembly, harness wiring for the IAC or the Powertrain Control Module. So checking the IAC next is the most logical step.

Oct 07, 2009 | 1998 Ford Ranger SuperCab

1 Answer

P0505 Code

First make sure that your wires to you iac(idle air control) motor are ok. Also that the pins in the connectors are not damaged. Most likeley you need to replace the iac motor and follow a relearn procedure for the pcm.(powertrain control module)
The iac is most likely stuck in the extented position causing it to starve for air. You have to hold your foot on the gas to keep the throttle plate open enough to let air by for the engine to run.

Jun 15, 2008 | 2000 Nissan Maxima

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