Ford Mustang (1999-2004) Service Manual: External Controls (Diagnosis and Testing)

Refer to Wiring Diagrams Cell 37 , Shift Lock for schematic and connector information.

Refer to Wiring Diagrams Cell 29 , Transmission Control for schematic and connector information.

Special Tool(s)

73 Digital Multimeter 105-R0051 or equivalent

Inspection and Verification

1. Verify the customer concern by operating the transmission external control.

2. Visually inspect for obvious signs of mechanical and electrical damage; refer to the following chart:

Visual Inspection Chart

Mechanical Electrical

  • Shift control linkage binding.

  • Shift lock actuator.

  • Shift control cable.

  • Interlock cable.
  • Circuitry.
  • Central junction box (CJB) fuse:
  • 17 (15A)
  • 28 (15A)
  • 35 (15A)
  • Brake pedal position (BPP) switch.
  • Wiring harness.
  • Loose or corroded connections.
  • Bulb.

3. If the concern is not visually evident, determine the symptom. GO to Symptom Chart .

Symptom Chart

Condition Possible Sources Action
  • The shift interlock system does not release/lock correctly
  • Circuitry.
  • CJB Fuse 17 (15A) or Fuse 35 (15A).
  • Shift lock actuator.
  • Brake pedal position (BPP) switch.
  • Go To Pinpoint Test A .
  • The shift control is out of correct gear relationship
  • Transmission shift cable and bracket.
  • Retainer bracket.
  • Shift control linkage out of adjustment.
  • Go To Pinpoint Test B .
  • Transmission range indicator does not correspond to the gear
  • Transmission shift cable bracket.
  • Transmission shift cable loose from the transmission retainer bracket.
  • Shift linkage.
  • TIGHTEN the bolts holding transmission shift cable bracket.
  • TIGHTEN the bolts.
  • VERIFY digital transmission range (DTR) sensor range for correct adjustment.
  • The Transmission Control Switch (TCS) Is Inoperative
  • CJB Fuse 28 (15A).
  • TCS.
  • TCS not cycled during self-test.
  • Powertrain control module (PCM).
  • Circuitry.
  • Go To Pinpoint Test C .
  • The Transmission Control Indicator Lamp (TCIL) Is Not Operating Correctly
  • Bulb.
  • Instrument cluster.
  • Powertrain control module.
  • REFER to Section.
  • Excessive Shift Effort
  • Transmission shift cable.
  • Cable bracket.
  • INSTALL a new transmission shift cable.
  • ADJUST the cable.

    TIGHTEN the screws.
  • Transmission Range Selector Lever Will Not Shift
  • Transmission shift cable
  • Broken transmission shift cable
  • Broken transmission shift cable
  • INSTALL a new transmission shift cable

Pinpoint Tests

PINPOINT TEST A: THE SHIFT INTERLOCK SYSTEM DOES NOT RELEASE/LOCK CORRECTLY

Test Step Result / Action to Take
A1 TEST THE BRAKE LIGHTS Yes

GO to A2 .

No

REFER to Section
  • Key in ON position.
  • Apply the brake pedal and observe the stoplamps.
  • Do the stoplamps illuminate?
A2 CHECK CIRCUIT 511 (LG) FOR AN OPEN Yes

GO to A3 .

No

REPAIR the circuit. TEST the system for normal operation.
  • Key in OFF position.
  • Disconnect: Shift Lock Actuator C2127.
  • Measure the voltage between the shift lock actuator C2127-3, Circuit 511 (LG), harness side and ground while depressing and releasing the brake pedal

  • Is the voltage greater than 10 volts with the brake pedal depressed and 0 volts with the brake pedal released?
A3 CHECK CIRCUIT 294 (WH/LB) FOR AN OPEN Yes

GO to A4 .

No

REPAIR the circuit. TEST the system for normal operation.
  • Key in ON position.
  • Measure the voltage between shift lock actuator C2127-1, Circuit 294 (WH/LB), harness side and ground.

  • Is the voltage greater than 10 volts?
A4 TEST CIRCUIT 1205 (BK) FOR AN OPEN Yes

INSTALL a new shift lock actuator. REFER to Brake Shift Interlock Actuator .

TEST the system for normal operation.

No

REPAIR the circuit. TEST the system for normal operation
  • Measure the resistance between shift lock actuator C2127-2, Circuit 1205 (BK), harness side and ground.

  • Is the resistance less than 5 ohms?

PINPOINT TEST B: THE SHIFT CONTROL IS OUT OF CORRECT GEAR RELATIONSHIP

Test Step Result / Action to Take
B1 CHECK THE SHIFT CONTROL LINKAGE Yes

GO to B2 .

No

REPAIR as necessary. TEST the system for normal operation.
  • Key in ON position.
  • Apply the brake pedal.
  • Actuate the transmission range selector lever in all ranges.
  • Observe the shift control linkage during operation.
  • Is the shift control linkage OK?
B2 CHECK THE TRANSMISSION SHIFT CABLE Yes

GO to B3 .

No

REPAIR as necessary. TEST the system for normal operation.
  • Check the transmission shift cable and bracket installation and tightness.
  • Is the transmission shift cable correctly installed and adjusted?
B3 CHECK THE LINKAGE/CABLE FOR CORRECT GEAR RELATIONSHIP Yes

VERIFY the correct adjustment of the digital transmission range (DTR) sensor. REFER to Section.

digital DTR sensor if necessary. TEST the system for normal operation.

No

ADJUST the transmission shift cable. REFER to Cable Adjustment . TEST the system for normal operation.
  • Apply the brake pedal.
  • Actuate the transmission range selector lever in all ranges.
  • Does the indicator match the gear selection?

PINPOINT TEST C: THE TRANSMISSION CONTROL SWITCH (TCS) IS INOPERATIVE

Test Step Result / Action to Take
C1 CHECK THE VOLTAGE TO THE TRANSMISSION CONTROL SWITCH Yes

GO to C2 .

No

REPAIR the circuit. TEST the system for normal operation.
  • Key in OFF position.
  • Disconnect: Transmission Control Switch C279.
  • Key in ON position.
  • Measure the voltage between TCS C279-3, Circuit 911 (WH/LG), harness side and ground

  • Is the voltage greater than 10 volts?
C2 CHECK THE TCS Yes

GO to C3 .

No

INSTALL a new TCS. Test the system for normal operation.
  • Measure the resistance between TCS Pin 3 (component side), and TCS Pin 4 (component side), while depressing and releasing the TCS.

  • Is the resistance less than 5 ohms with the TCS depressed and greater than 10,000 ohms with the TCS released?
C3 CHECK CIRCUIT 224 (TN/WH) FOR AN OPEN Yes

REFER to Powertrain Control/Emissions Diagnosis (PC/ED) manual.

No

REPAIR the circuit. TEST the system for normal operation
  • Key in OFF position.
  • Disconnect: PCM C175.
  • Measure the resistance between TCS C279-4, Circuit 224 (TN/WH), harness side and PCM C175-29, Circuit 224 (TN/WH), harness side.

  • Is the resistance less than 5 ohms?
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