DTC P0506: IDLE SPEED LOW OR DTC P0507: IDLE SPEED HIGH
Idle Air Control (IAC) valve is located on throttle body. It consists of a movable pintle, driven by a gear attached to an electric motor called a stepper motor. The IAC valve motor is a 2 phase bi-polar permanent magnet stepper motor that is capable of highly accurate rotation, or movement, every time polarity of a winding is changed. Polarity can be seen when observing a test light connected between ground or B+ and an IAC valve circuit while the Powertrain Control Module (PCM) is attempting to change engine RPM (test light will flash on or off each time polarity is changed). The PCM does not use a physical sensor to determine IAC pintle position, but uses a predicted number of counts, one count represents one change in polarity which equals one step of the stepper motor. The PCM counts the steps it has commanded to determine IAC pintle position. The PCM uses IAC valve to control engine idle speed. It does this by changing pintle position in the idle air passage of the throttle body. This varies airflow around throttle plate when throttle is closed. To determine desired position of IAC pintle at idle or during deceleration, the PCM refers to the following inputs: engine RPM, battery voltage, air temperature, engine coolant temperature, throttle position sensor angle, engine load, and vehicle speed. When ignition is turned off after an ignition cycle, the PCM will first seat the IAC pintle in the air by-pass bore, and then retract it a predetermined amount of counts to allow proper amount of air to by-pass throttle plate for engine start-up. This procedure is known as an IAC reset.
Code Enable Criteria
DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0335, P0336, P0340, P0341, P0385, P0386, P0401, P0403, P0404, P0405, P0440, P0442, P0443, P0446, P0449, P1106, P1107, P1111, P1112, P1114, P1115, P1121, P1122, P1336, P1372, P1404 or P1441 is not set.
Engine coolant temperature is more than -40 F (-40 C).
Intake air temperature is more than -1 F (-18 C).
Ignition voltage is 10.5-16 volts.
Barometric pressure is more than 9.43 psi (65 kPa).
Engine run time is more than 40 seconds.
Transmission gear state has not changed for 3 seconds.
Torque converter clutch state has not changed in 3 seconds.
Throttle position sensor is less than 1.5 percent.
Spark advance is less than 12.39 degrees.
Spark retard is more than -13.79 degrees.
Vehicle speed sensor is less than 2 MPH.
Listed conditions exist present for 3 seconds.
DTC P0741: TCC SYSTEM STUCK OFF
Tips Click a link to view tip
Tech1Tip: check engine light on
NOTE:For circuit identification, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS.
The PCM controls the Torque Converter Clutch Pulse Width Modulation (TCC PWM) solenoid valve. The solenoid controls the hydraulic fluid for TCC apply and release. When the TCC is applied, the engine is coupled directly to the transaxle through the TCC. The TCC slip speed should be near zero.
If the PCM detects high torque converter slip when the TCC is commanded on, then DTC P0741 sets. DTC P0741 is a type "B" DTC.
Conditions For Running DTC P0741
DTC will run under the following conditions:
No TP sensor DTCs P0121, P0122 or P0123.
No VSS DTCs P0502 or P0503.
No ISS DTCs P0716 or P0717.
No TCC stuck on DTC P0742.
No internal mode switch DTCs P1820, P1822, P1823 or P1825.
No TCC PWM solenoid valve DTC P1860.
The engine run time is greater than 5 seconds.
The time since the gearshift lever change is greater than 6 seconds.
The internal mode switch indicates "D2", "D3" or "D4".
The transaxle gear ratio indicates 2nd, 3rd or 4th gear.
The transmission fluid temperature is 68-271 F (20-133 C).
The throttle angle is 10-50 percent.
The engine torque is 32-159 ft. Lbs. (43-215 N.M).
The TCC solenoid valve is commanded on.
Conditions For Setting DTC P0741
DTC will set under the following condition:
TCC slip speed exceeds its limit for a given torque for 5 seconds. See TCC SLIP SPECIFICATIONS table.
TCC SLIP SPECIFICATIONS
Torque - Ft. Lbs. (N.M)Slip Speed Limit - RPM
Action Taken By PCM
PCM performs the following if DTC is set:
The PCM illuminates the MIL during the second consecutive trip in which the conditions for setting the DTC are met.
The PCM inhibits 4th gear if the transaxle is in hot mode.
The PCM records the operating conditions when the conditions for setting the DTC are met. The PCM stores this information as freeze frame and failure records.
The PCM stores DTC P0741 in PCM history during the second consecutive trip in which the conditions for setting the DTC are met.
Conditions For Clearing DTC P0741
DTC will clear under the following conditions:
The PCM turns off the MIL during the third consecutive trip in which the diagnostic test runs and passes.
A scan tool can clear the DTC.
The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
The PCM cancels the DTC default actions when the ignition is off long enough to power down the PCM.
Wednesday, December 8th, 2010 AT 5:27 PM