Section 07-01: Transmission, Automatic—AODE
1994 Mustang Workshop Manual
OPERATION

Transmission Electronic Control System



Electrical Component Function—Component Illustrations






Powertrain Control Module (PCM) 12A650:
The operation of the AODE automatic transmission is controlled by the powertrain control module . Many input sensors provide information to the powertrain control module. The powertrain control module then controls actuators which determine transmission operation.
5.0L DTCs: 511, 512, 513
3.8L DTCs: P0605, P1605



Engine Coolant Temperature (ECT) Sensor 12A648:
The engine coolant temperature sensor detects temperature of engine coolant and supplies information to the powertrain control module . The engine coolant temperature sensor is installed into the heater outlet fitting or cooling passage on the engine. For engine control applications, the engine coolant temperature sensor signal is used to modify ignition timing, EGR flow and air- to-fuel ratio as a function of engine coolant temperature. On electronic instrument clusters, the engine coolant temperature sensor output is used to control the coolant temperature indicator.
Transmission Function: The engine coolant temperature sensor controls torque converter clutch operation.
Symptoms: Torque converter clutch will always be off, resulting in reduced fuel economy.
5.0L DTCs: 116, 117, 118
3.8L DTCs: P0117, P0118, P1116, P1117



Intake Air Temperature (IAT) Sensor 12A697:
The intake air temperature sensor provides the multiport fuel injection (MFI) system with mixture (fuel and air) temperature information. The intake air temperature sensor is used both as a density corrector for airflow calculation and to proportion cold enrichment fuel flow. The sensor is installed into a cylinder runner of the intake manifold or mounted in the air cleaner assembly and provides the fuel system with mixture temperature information.
Transmission Function: Intake air temperature sensor is used in determining EPC pressure.
Symptoms: Incorrect EPC pressure either high or low will result in either harsh or soft shifts.
5.0L DTCs: 114, 112, 113
3.8L DTCs: P0112, P0113, P0114



Transmission Control Switch (TCS) and Transmission Control Indicator Lamp (TCIL)
The transmission control switch is a momentary contact switch. When the switch is pressed, a signal is sent to the powertrain control module to allow automatic shifts from first through fourth gears or first through third gears only. The powertrain control module then energizes the transmission control indicator lamp (TCIL).a
Sensor: Transmission Control Switch (TCS)
Transmission Function: Disable fourth gear operation.
Symptoms: No overdrive cancel when switch is cycled.
5.0L DTC: 632 tested during Key On Engine Off (KOEO) Self-Test.
3.8L DTC: P1780 tested during Key On Engine Off (KOEO) Self-Test.
Transmission Control Indicator Lamp (TCIL)
Transmission Function: Indicates overdrive cancel mode activated (lamp ON) and EPC circuit shorted (lamp flashing) for monitored sensor failure.
Symptoms:
  • FAILED ON - Overdrive cancel mode always indicated, no flashing for EPC circuit shorted or monitored sensor failure.
  • FAILED OFF - Overdrive cancel mode never indicated, no flashing for EPC circuit shorted or monitored sensor failure.
5.0L DTC: 623
3.8L DTC: TBD
a TCIL will also flash if the EPC solenoid circuit is shorted.


Transmission Oil Temperature (TOT) Sensor 7H141:
The transmission oil temperature sensor is located on the transmission main control valve body . It is a temperature sensitive device called a thermistor. The resistance value of the TOT will vary with temperature change. The powertrain control module monitors the voltage across the TOT to determine the temperature of the transmission oil.
Transmission Function: The powertrain control module uses this voltage signal to determine whether a cold start shift schedule is necessary. The shift schedule is compensated when the transmission fluid temperature is cold. The powertrain control module also inhibits torque converter clutch operation at low transmission fluid temperatures and corrects EPC pressures for temperature.
Symptoms: Converter clutch engagement and stabilized shift schedules happen too soon after a cold start.
5.0L DTCs: 636, 637, 638, 657
3.8L DTCs: P0712, P0713, P1711, P1783



Manual Lever Position (MLP) Sensor 7F293:
The powertrain control module sends a voltage signal to the manual lever position sensor (MLP). The MLP incorporates a series of step-down resistors which act as a voltage divider. The powertrain control module monitors this voltage which corresponds to the position of the manual lever (P, R, N, D, 2, 1). The MLP is located on the outside of the transmission at the manual control lever.
NOTE: The sensor also contains the park/neutral position and backup lamp circuits.
  1. 359 GY/R PCM Signal Return
  2. 33 W/PK Start
  3. 140 BK/PK Back-Up Lamps
  4. 298 P/O Accessory Feed
  5. 32 R/LB Start
  6. 199 LB/Y Sensor Signal to PCM
Transmission Function: Determines desired gear and EPC pressure.
Symptoms: Engagement concerns, wrong gear, no shifts.
5.0L DTCs: 522, 634
3.8L DTCs: P0707, P0708, P1705, P1706, P1709



Brake On/Off (BOO) Switch 13480:
The brake on/off switch tells the powertrain control module when the brakes are applied. The switch closes when brakes are applied and opens when they are released.
Transmission Function: Disengage torque converter clutch when brake is applied.
Symptoms:
  • Failed "ON"—torque converter clutch will not engage at less than one-third throttle.
  • Failed "OFF" or not connected—torque converter clutch will not disengage when brake is applied.
5.0L DTC: 536
3.8L DTCs: P0703, P1703



Electronic Ignition (EI) System:
The electronic ignition system consists of a crankshaft position sensor, ignition control module, two four tower ignition coils and the powertrain control module. The ignition control module operates by sending crankshaft position information from the crankshaft position sensor to the ignition control module. The module generates a PIP signal (engine rpm) and sends it to the powertrain control module.
Transmission Function: Uses rpm signal in the transmission strategy. Wide-open throttle (WOT) shift control, torque converter clutch control and EPC.
Symptoms: Harsh engagements and shifts, late WOT shift, no torque converter clutch engagement.
5.0L DTCs: 211, 212, 214 through 217, 232, 238 and 241
3.8L DTCs: P0300 through P0308, P0320, P0340, P1351 through P1364



Air Conditioning Clutch (ACC) 2884:
An electro-magnetic clutch is energized when the A/C cyclic switch closes. The A/C cyclic switch is located on the A/C suction accumulator/drier. The closing of the A/C cyclic switch completes the circuit to the A/C clutch and draws it into engagement with the A/C compressor drive shaft.
Transmission Function: Adjust EPC pressure when A/C clutch is engaged to compensate for additional load on the engine.
Symptoms:
  • Failed "ON"—EPC pressure slightly low with A/C OFF.
  • Failed "OFF"—EPC pressure slightly high with A/C ON.
5.0L DTC: 539
3.8L DTC: P1460



Mass Air Flow (MAF) Sensor 12B579:
The mass airflow sensor directly measures the mass of air flowing into the engine. The sensor output is a DC (analog) signal ranging from 0.5 volt to 5 volts used by the powertrain control module to calculate injector pulse width. For transmission strategies, the mass airflow sensor is used for EPC pressure control, shift and torque converter clutch scheduling.
Transmission Function: EPC pressure control, shift and torque converter clutch scheduling.
Symptoms: High/low EPC pressure, incorrect shift schedule, incorrect converter engagement scheduling and symptoms similar to a throttle position sensor malfunction.
5.0L DTCs: 157, 158, 159, 184 and 185
3.8L DTCs: P0102, P0103, P1100, P1101



Throttle Position (TP) Sensor 9B989:
The throttle position sensor is a potentiometer mounted on the throttle body. The throttle position sensor detects the position of the throttle plate and sends this information to the powertrain control module as a varying voltage signal.
Transmission Function: Shift scheduling, EPC pressure control, torque converter clutch control.
Symptoms: Harsh engagements, firm shift feel, abnormal shift schedule, torque converter clutch does not engage, torque converter clutch cycling.
5.0L DTCs: 121, 122, 123, 124, 125, 167
3.8L DTCs: P0122, P0123, P1120, P1121, P1124, P1125



Output Shaft Speed Sensor (OSS) 7H103:
An output shaft speed sensor is a magnetic pickup, located at the output shaft ring gear that sends a signal to the powertrain control module to indicate transmission output shaft speed.
Transmission Function: Torque converter clutch control, shift scheduling, used in determining EPC pressure.
Symptoms: No converter engagements, harsh shifts, abnormal shift schedules.
5.0L DTC: 639
3.8L DTC: P0720



Vehicle Speed Sensor (VSS) 9E731:
The vehicle speed sensor is a magnetic pickup that sends a signal to the powertrain control module. This vehicle speed sensor signal tells the PCM vehicle speed.
Transmission Function: Modifies upshift schedules.
Symptoms: Shift engagement/disengagement (hunting) on grades.
5.0L DTC: 452
3.8L DTC: P0500



Shift Solenoid Assembly, Shift Control Solendoids 1 and 2 (7G484)
Two ON/OFF shift solenoids are used for electronic shift scheduling. One unit containing the two solenoids is located in the main control assembly. The solenoids are two-way, normally open style.
Transmission Function: Solenoids SS-1 and SS-2 provide gear selection of first through fourth gears by controlling the pressure to the three shift valves.
SS1 Symptoms: Improper gear selection depending on failure mode and manual lever position.
  • Failed "ON"—first and fourth gear only.
  • Failed "OFF"—second and third gear only.
5.0L DTCs: 617**, 618**, 619**, 621*
3.8L DTCs: P0750*, P0751**, P1731**, P1732**, P1733**, P1751
SS2 Symptoms: Improper gear selection depending on failure mode and manual lever position.
  • Failed "ON"—third and fourth gear only.
  • Failed "OFF"—first and second gear only.
5.0L DTCs: 618**, 619**, 622*
3.8L DTCs: P0755*, P0756**, P1732**, P1733**, P1756
SS1 and SS2 Symptoms:
  • Both failed "ON"—fourth gear only.
  • Both failed "OFF"—second gear only.
5.0L DTCs: 621*, 622*
3.8L DTCs: P0750*, P0751, P0755*, P0756
* Output circuit check, generated only by electrical conditions.
** May also be generated by some non-electrical transmission component condition.



Torque Converter Clutch (TCC) Solenoid 7G136:
The torque converter clutch solenoid is used to control the apply and release of the torque converter clutch.
Transmission Function: Used to engage the torque converter clutch.
Symptoms:
  • Failed "ON"—engine stalls in second gear (D, 2 range) at low idle speeds with the brake applied.
  • Failed "OFF"—torque converter never engages.
5.0L DTCs: 628**, 652*, 656**
3.8L DTCs: P0741**, P0743*, P1741**, P1742, P1743
* Output circuit check, generated only by electrical conditions.
** May also be generated by some non-electrical transmission component condition.



Electronic Pressure Control (EPC) Solenoid 7G383:
The EPC solenoid regulates transmission EPC pressure. EPC valve pressure is used to control line pressure and the 2-3 backout valve function.
Actuator: Electronic pressure control (EPC)
Transmission Function: Regulates EPC pressure, 2-3 backout valve control, line pressure.
Symptoms:
  • Failed "ON"—Minimum EPC pressure (minimum capacity), limit engine torque (alternate firing).
  • Failed "OFF"— Maximum EPC pressure, harsh engagements, harsh shifts.
5.0L DTCs: 624, 625
3.8L DTCs: P1746, P1747