1993 Mustang

Section 07-01A: Transmission, Automatic, A4LD

1993 Mustang Workshop Manual

DIAGNOSIS AND TESTING

Electrical

Electronic Control System, Actuators and Sensors

Electronic Control

Powertrain Control Module (PCM)

Inputs

Engine Coolant Temperature Sensor (ECT)
Brake ON/OFF Switch (BOO)
Electronic Ignition (EI)
Profile Ignition Pulse (PIP)
Throttle Position Sensor (TP)
Vehicle Speed Sensor (VSS)

Outputs

Shift Solenoid 3-4/4-3 (SS 3-4/4-3)
Torque Converter Clutch (TCC)

Powertrain Control Module (PCM)

The operation of the A4LD automatic transmission is partially controlled by the Powertrain Control Module (PCM). Many input sensors provide information to the PCM, which then controls the actuators which affect the SS 3-4/4-3 solenoid and the torque converter clutch (TCC) solenoid during normal transmission operation.

Diagnostic Trouble Codes: 511, 512, 513

Engine Coolant Temperature (ECT) Sensor

The Engine Coolant Temperature (ECT) Sensor detects the temperature of engine coolant and supplies the information to the Powertrain Control Module (PCM).

The ECT sensor is threaded into the heater outlet fitting or cooling passage on the engine. For engine control applications, the ECT signal is used to modify ignition timing, EGR flow, and air-to-fuel ratio as a function of engine coolant temperature. On electronic instrument cluster applications, the ECT output is used to control a coolant temperature indicator.

Transmission Function: ECT is used to control torque converter clutch operation.

Symptoms: Torque Converter Clutch will always be "OFF."

Diagnostic Trouble Codes: 116, 117, 118.

Brake On-Off (BOO) Switch

The Brake On-Off switch (BOO) tells the PCM when the brakes are applied. The switch is closed when the brakes are applied and open when they are released.

Transmission Function: Disengage torque converter clutch when brake is applied.

Symptoms: Failed "ON" — Torque converter clutch will not engage.

Failed "OFF" — Converter will not disengage when brakes are applied.

Diagnostic Trouble Codes: 536.

Electronic Ignition (EI) System

The Electronic Ignition (EI) System consists of a Crankshaft Position sensor (CKP), an EI Module, two four tower Coil Packs, and the PCM. The EI System operates by sending crankshaft position information from the CKP sensor to the EI module. The module generates a PIP signal (engine RPM) and sends it to the PCM.

Transmission Function: Uses RPM signal in the transmission strategy for 3-4 and 4-3 shift scheduling and torque converter clutch engagement.

Symptoms: No 3-4 or 4-3 shifts, no torque converter clutch engagement.

Diagnostic Trouble Codes: 211-217, 232.

Profile Ignition Pulse (PIP) — Gasoline

On gasoline engines, the Profile Ignition Pulse (PIP) signal is produced by a Hall-Effect device in the distributor. It tells the PCM the engine RPM and the crankshaft position.

Transmission Function: Uses RPM signal in the transmission strategy for 3-4 and 4-3 shift scheduling and torque converter clutch control.

Symptoms: No 3-4 or 4-3 shifts, no torque converter clutch engagement.

Diagnostic Trouble Codes: 211-217.

Throttle Position (TP) Sensor

The Throttle Position sensor (TP) is a potentiometer mounted on the throttle body. The TP sensor detects the position of the throttle plate and sends this information to the PCM as a varying voltage signal.

Transmission Function: Used in determining 3-4/4-3 shift scheduling and torque converter clutch engagement.

Symptoms: Abnormal shift schedule, torque converter clutch does not engage, torque converter clutch cycling.

Diagnostic Trouble Codes: 121, 122, 123, 125, 167.

Vehicle Speed Sensor (VSS)

The Vehicle Speed Sensor (VSS) is a magnetic pickup that sends a signal to the PCM. This VSS signal tells the PCM the vehicle speed.

Transmission Function: Used in determining shift schedules and torque converter clutch control schedule.

Symptoms: No 3-4/4-3 shifts, no torque converter clutch engagement.

Diagnostic Trouble Codes: 452.

Torque Converter Clutch Solenoid (TCC)

The torque torque converter clutch solenoid (TCC) 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," the torque converter clutch would always be engaged above 30 mph.

Failed "OFF," the torque converter clutch will not engage.

Diagnostic Trouble Codes: 629, TCC solenoid circuit failure.

Solenoid PCM Signal Output Pin KOEO On-Board Diagnostics

TCC 53 or 14 89/629

SS 3/4 52 or 51 86/566

Solenoid	PCM Signal Output Pin	KOEO On-Board Diagnostics
TCC	53 or 14	89/629
SS 3/4	52 or 51	86/566

Shift Solenoid 3-4 (SS 3-4)

The 3-4 shift solenoid is used to control the 3-4/4-3 shift valve.

Transmission Function: Used to shift from third gear to fourth gear, and fourth gear to third gear.

Symptoms: Failed "ON," vehicle has lack of acceleration performance at start out.

Failed "OFF," No 3-4 upshift or 4-3 downshift.

Diagnostic Trouble Codes: 566, 3-4 shift solenoid circuit failure.

EEC-IV On-Board Diagnostic Trouble Code Description

DTC COMPONENT DESCRIPTION CONDITION SYMPTOM/ACTIONS

111 SYSTEM Pass No fault detected. Fault not detected by PCM.

116 ECT ECT sensor out of on-board diagnostic range ECT sensor signal higher or lower than expected during KOEO, KOER. Rerun on-board diagnostic at normal operating temperature.

117 ECT ECT below min voltage 125°C 254°F indicated ECT sensor signal higher or lower than expected during KOEO, KOER. TCC will always be off.^a

118 ECT ECT above max voltage -40°C-40°F ECT sensor signal higher or lower than expected during KOEO, KOER. TCC will always be off. ¹

121 TP TP out of on-board diagnostic range TP sensor not at idle position during KOEO. Rerun on-board diagnostic at appropriate position.

122 TP TP circuit below min voltage Voltage above or below specification for on-board diagnostic or during normal vehicle operation. Harsh engagements, firm shift feel, abnormal shift schedule, TCC does not engage.¹

123 TP TP circuit above max voltage Voltage above or below specification for on-board diagnostic or during normal vehicle operation. Harsh engagements, firm shift feel, abnormal shift schedule, TCC does not engage.¹

125 TP TP circuit voltage lower than expected Voltage above or below specification for on-board diagnostic or during normal vehicle operation. Harsh engagements, firm shift feel, abnormal shift schedule, TCC does not engage.¹

167 TP Insufficient TP change during goose test Throttle not depressed during KOER. Rerun on-board diagnostic and depress throttle when indicated.

211-213, 232 RPM/PIP RPM/PIP diagnostic trouble codes. EI system has a malfunction which may cause a transmission concern. No 3-4, 4-3, and no TCC engagement.¹

211-213 EI system EI diagnostic trouble codes. RPM/PIP — in an EI system has a malfunction which may cause a transmission concern. No 3-4, 4-3, and no TCC engagement.¹

452 VSS VSS circuit concern Insufficient input from VSS sensor to PCM. No 3-4, 4-3, and no TCC engagement.¹

511 PCM Read Only Memory test concern Read Only Memory test failure KOEO. Rerun test.¹

512 PCM Keep Alive Memory test concern Keep Alive Memory test failure. Rerun test.¹

513 PCM Internal voltage concern Internal voltage higher or lower than specification, failure KOEO. Rerun test.¹

536 BOO Brake not actuated during on-board diagnostic Brake not cycled during KOER. Rerun test.¹

536 BOO BOO switch circuit failure Brake on/off circuit failure. Failed ON: TCC will not engage. Failed OFF: TCC will not disengage when brakes are applied.¹

566^b SS 3-4 SS 3-4 circuit fault KOEO SS 3-4 circuit failure. No 3-4, 4-3 shift. Refer to Pinpoint Test "A" .

629^b TCC TCC circuit concern TCC circuit failure. Failed ON: engine stalls at low idle speeds.
Failed OFF: no torque converter clutch engagements. Refer to Pinpoint Test "C" .

DTC	COMPONENT	DESCRIPTION	CONDITION	SYMPTOM/ACTIONS
111	SYSTEM	Pass	No fault detected.	Fault not detected by PCM.
116	ECT	ECT sensor out of on-board diagnostic range	ECT sensor signal higher or lower than expected during KOEO, KOER.	Rerun on-board diagnostic at normal operating temperature.
117	ECT	ECT below min voltage 125°C 254°F indicated	ECT sensor signal higher or lower than expected during KOEO, KOER.	TCC will always be off.^a
118	ECT	ECT above max voltage -40°C-40°F	ECT sensor signal higher or lower than expected during KOEO, KOER.	TCC will always be off. ¹
121	TP	TP out of on-board diagnostic range	TP sensor not at idle position during KOEO.	Rerun on-board diagnostic at appropriate position.
122	TP	TP circuit below min voltage	Voltage above or below specification for on-board diagnostic or during normal vehicle operation.	Harsh engagements, firm shift feel, abnormal shift schedule, TCC does not engage.¹
123	TP	TP circuit above max voltage	Voltage above or below specification for on-board diagnostic or during normal vehicle operation.	Harsh engagements, firm shift feel, abnormal shift schedule, TCC does not engage.¹
125	TP	TP circuit voltage lower than expected	Voltage above or below specification for on-board diagnostic or during normal vehicle operation.	Harsh engagements, firm shift feel, abnormal shift schedule, TCC does not engage.¹
167	TP	Insufficient TP change during goose test	Throttle not depressed during KOER.	Rerun on-board diagnostic and depress throttle when indicated.
211-213, 232	RPM/PIP	RPM/PIP diagnostic trouble codes.	EI system has a malfunction which may cause a transmission concern.	No 3-4, 4-3, and no TCC engagement.¹
211-213	EI system	EI diagnostic trouble codes.	RPM/PIP — in an EI system has a malfunction which may cause a transmission concern.	No 3-4, 4-3, and no TCC engagement.¹
452	VSS	VSS circuit concern	Insufficient input from VSS sensor to PCM.	No 3-4, 4-3, and no TCC engagement.¹
511	PCM	Read Only Memory test concern	Read Only Memory test failure KOEO.	Rerun test.¹
512	PCM	Keep Alive Memory test concern	Keep Alive Memory test failure.	Rerun test.¹
513	PCM	Internal voltage concern	Internal voltage higher or lower than specification, failure KOEO.	Rerun test.¹
536	BOO	Brake not actuated during on-board diagnostic	Brake not cycled during KOER.	Rerun test.¹
536	BOO	BOO switch circuit failure	Brake on/off circuit failure.	Failed ON: TCC will not engage. Failed OFF: TCC will not disengage when brakes are applied.¹
566^b	SS 3-4	SS 3-4 circuit fault KOEO	SS 3-4 circuit failure.	No 3-4, 4-3 shift. Refer to Pinpoint Test "A" .
629^b	TCC	TCC circuit concern	TCC circuit failure.	Failed ON: engine stalls at low idle speeds. Failed OFF: no torque converter clutch engagements. Refer to Pinpoint Test "C" .

^a Refer to Powertrain Control/Emission Diagnosis Manual for diagnosis procedures.
^b Output circuit check, generated only by electrical conditions.