Ford Mustang (1999-2004) Service Manual: Turn Signal and Hazard Lamps

Refer to Wiring Diagrams Cell 90 , Turn/Stop/Hazard Lamps for schematic and connector information.

Special Tool(s)

73 III Automotive Meter 105-R0057 or equivalent

Inspection and Verification

1. Verify the customer concern.

2. Visually inspect for the following obvious signs of mechanical and electrical damage.

Visual Inspection Chart

Mechanical

Electrical

  • Multifunction switch
  • Central junction box (CJB) Fuse 13 (15A).
  • CJB Fuse 18 (15A).
  • Circuitry
  • Electronic flasher
  • Turn signal/hazard lamp

3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

4. If the cause is not visually evident, verify the symptom and refer to the Symptom Chart.

Symptom Chart

Condition Possible Sources Action
  • The turn signal lamps are never on
  • Central junction box (CJB) fuse 13 (15A).
  • CJB Fuse 18 (15A).
  • Circuitry.
  • Multifunction switch.
  • Electronic flasher
  • Go To Pinpoint Test J .
  • The hazard flasher lamps are never on
  • Central junction box (CJB) fuse 13 (15A).
  • Circuitry.
  • Multifunction switch.
  • Electronic flasher
  • Go To Pinpoint Test K .
  • One turn signal/hazard lamp is never on
  • Turn signal/hazard flasher lamp.
  • Circuitry.
  • REPAIR inoperative turn signal/hazard flasher lamp circuit
  • LF Circuit 3 (LG/WH).
  • RF Circuit 2 (WH/LB).
  • LR Circuit 9 (LG/OG).
  • RR Circuit 5 (OG/LB).
  • The turn signal lamps are always on
  • Multifunction switch.
  • INSTALL a new multifunction switch; REFER to Section . TEST the system for normal operation
  • The hazard flasher lamps are always on
  • Multifunction switch
  • INSTALL a new multifunction switch; REFER to Section . TEST the system for normal operation.

Pinpoint Tests

PINPOINT TEST J: THE TURN SIGNAL LAMPS ARE NEVER ON

Test Step Result / Action to Take
J1 CHECK THE VOLTAGE TO THE ELECTRONIC FLASHER Yes

GO to J2 .

No

REPAIR the circuit in question. TEST the system for normal operation.
  • Disconnect: Electronic Flasher C2141.
  • Key in ON position.
  • Measure the voltage between the following electronic flasher C2141 circuits, harness side and ground.
  • Pin 2, Circuit 1039 (BK/YE).
  • Pin 3, Circuit 383 (RD/WH).

  • Are the voltages greater than 10 volts?
J2 CHECK CIRCUIT 44 (LB) Yes

GO to J3 .

No

REPAIR the circuit.

TEST the system for normal operation.
  • Key in OFF position.
  • Disconnect: Multifunction Switch C202b.
  • Measure the resistance between multifunction switch C202b Pin 44, Circuit 44 (LB), harness side and the electronic flasher C2141 Pin 1, Circuit 44 (LB), harness side; and between multifunction switch C202b Pin 44, Circuit 44 (LB), harness side and ground.

  • Is the resistance less than 5 ohms between the multifunction switch and the electronic flasher, and greater than 10,000 ohms between the multifunction switch and ground?
J3 CHECK THE CONTINUITY OF THE MULTIFUNCTION SWITCH Yes

INSTALL a new electronic flasher.

TEST the system for normal operation.

No

INSTALL a new multifunction switch.

REFER to Section. TEST the system for normal operation.
  • Carry out the multifunction switch component test.

    Refer to Wiring Diagrams Cell 149 for schematic and connector information.

  • Is the switch OK?

PINPOINT TEST K: THE HAZARD FLASHER LAMPS ARE NEVER ON

Test Step Result / Action to Take
K1 CHECK THE VOLTAGE TO THE ELECTRONIC FLASHER Yes

GO to K2 .

No

REPAIR the circuit.

TEST the system for normal operation.
  • Disconnect: Electronic Flasher C2141.
  • Measure the voltage between electronic flasher C2141 Pin 3, Circuit 383 (RD/WH), harness side and ground.

  • Is the voltage greater than 10 volts?
K2 CHECK CIRCUIT 385 (WH/RD) Yes

GO to K3 .

No

REPAIR the circuit.

TEST the system for normal operation.
  • Disconnect: Multifunction Switch C202b.
  • Measure the resistance between multifunction switch C202b Pin 385, Circuit 385 (WH/RD), harness side and electronic flasher C2141 Pin 4, Circuit 385 (WH/RD), harness side; and between multifunction switch C202b Pin 385, Circuit 385 (WH/RD), harness side and ground.

  • Is the resistance less than 5 ohms between the multifunction switch and the electronic flasher, and greater than 10,000 ohms between the multifunction switch and ground?
K3 CHECK THE CONTINUITY OF THE MULTIFUNCTION SWITCH Yes

INSTALL a new electronic flasher.

TEST the system for normal operation.

No

INSTALL a new multifunction switch; REFER to Section. TEST the system for normal operation.
  • Carry out the multifunction switch component test.

    Refer to Wiring Diagrams Cell 149 for schematic and connector information.

  • Is the switch OK?
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