Ford Mustang Service Manual: Instrument Cluster (Diagnosis and Testing)

Instrument Cluster and Panel Illumination (Diagnosis and Testing)

Refer to Wiring Diagrams Cell 71 , Instrument Illumination for schematic and connector information.

Special Tool(s)

73III Automotive Meter 105-R0057 or equivalent

Inspection and Verification

NOTE: A new instrument cluster must be reconfigured.

NOTE: The instrument panel dimmer switch is a part of the headlamp switch.

1. Verify the customer concern.

2. Visually inspect for obvious signs of electrical damage.

Visual Inspection Chart

Electrical

Central junction box (CJB) fuses:

5 (15A)

21 (5A)

34 (20A)

37 (5A)

32 (15A)

27 (20A)

Circuitry
Damaged switch

3. If the fault is not visually evident, determine the symptom and proceed to the Symptom Chart.

Symptom Chart

Condition	Possible Sources	Action
The control illumination is inoperative	Central junction box (CJB) fuse 37 (5A). Circuitry. Headlamp switch.	Go To Pinpoint Test A .
The instrument cluster illumination is inoperative	Circuitry. Instrument cluster. Bulb(s).	Go To Pinpoint Test B .
The climate control illumination is inoperative	Circuitry. Bulb(s).	Go To Pinpoint Test C .
The audio system illumination is inoperative	Circuitry. Audio unit.	Go To Pinpoint Test D .
A single illumination source is inoperative	Circuitry. Switch.	Go To Pinpoint Test E .

Pinpoint Tests

PINPOINT TEST A: THE CONTROL ILLUMINATION IS INOPERATIVE

Test Step	Result / Action to Take
A1 CHECK PARKING LAMPS	Yes Place the headlamp switch in the OFF position. GO to A2 . No REFER to Section.
Place the headlamp switch in the ON position. Are the exterior lamps on?
A2 CHECK HEADLAMP SWITCH	Yes RECONNECT the headlamp switch. GO to A3 . No INSTALL a new headlamp switch. REFER to Section. TEST the system for normal operation.
Key in OFF position. Carry out the headlamp switch components test; Refer to Wiring Diagrams Cell 149 for schematic and connector information. Is the headlamp switch OK?
A3 CHECK CIRCUIT 1045 (DB/WH)	Yes REPAIR circuit 19 (LB/RD). TEST the system for normal operation. No REPAIR circuit 1045 (DB/WH). TEST the system for normal operation.
Place the headlamp switch in the ON position. Rotate the instrument panel dimmer switch to the full illumination position. Measure voltage between central junction box (CJB) fuse 37 (5A) and ground. Is the voltage greater than 10 volts?

PINPOINT TEST B: THE INSTRUMENT CLUSTER ILLUMINATION IS INOPERATIVE

Test Step	Result / Action to Take
B1 CHECK VOLTAGE TO INSTRUMENT CLUSTER ILLUMINATION	Yes GO to B2 . No REPAIR the circuit. TEST the system for normal operation.
Disconnect: Instrument Cluster . Place the headlamp switch in the ON position. Rotate the instrument panel dimmer switch to the full illumination position. Measure the voltage between the instrument cluster C220b pin 4, circuit 19 (LB/RD), harness side and ground. Is the voltage greater than 10 volts?
B2 CHECK GROUND TO INSTRUMENT CLUSTER	Yes INSTALL a new instrument cluster. REFER to Section. TEST the system for normal operation. No REPAIR the circuit. TEST the system for normal operation.
Place the headlamp switch in the OFF position. Measure the resistance between the instrument cluster C220b pin 1, circuit 1205 (BK), harness side and ground. Are the resistances less than 5 ohms?

PINPOINT TEST C: THE CLIMATE CONTROL ILLUMINATION IS INOPERATIVE

Test Step	Result / Action to Take
C1 CHECK VOLTAGE TO CLIMATE CONTROL ILLUMINATION	Yes GO to C2 . No REPAIR the circuit. TEST the system for normal operation.
Disconnect: Function Selector Switch C294b . Place the headlamp switch in the ON position. Rotate the instrument panel dimmer switch to the full illumination position. Measure the voltage between the function selector switch C294b pin 2, circuit 19 (LB/RD), harness side and ground. Is the voltage greater than 10 volts?
C2 CHECK GROUND TO CLIMATE CONTROL	Yes INSTALL new illumination bulb(s). REFER to Section . No REPAIR the circuit. TEST the system for normal operation.
Measure the resistance between the function selector switch C294b pin 1, circuit 1205 (BK), harness side and ground. Is the resistance less than 5 ohms?

PINPOINT TEST D: THE AUDIO SYSTEM ILLUMINATION IS INOPERATIVE

Test Step	Result / Action to Take
D1 CHECK VOLTAGE TO AUDIO UNIT	Yes GO to D2 . No REPAIR the circuit. TEST the system for normal operation.
Disconnect: Audio Unit C290a. Place the headlamp switch in the ON position. Rotate the instrument panel dimmer switch to the full illumination position. Measure the voltage between the audio unit C290a pin 1, circuit 19 (LB/RD), harness side and ground. Is the voltage greater than 10 volts?
D2 CHECK GROUND TO AUDIO UNIT	Yes REMOVE the audio unit and SEND it to an authorized Ford audio systems repair facility. TEST the system for normal operation. No REPAIR the circuit. TEST the system for normal operation.
Measure the resistance between the audio unit C290a pin 2, circuit 1205 (BK), harness side and ground. Is the resistance less than 5 ohms?

PINPOINT TEST E: A SINGLE ILLUMINATION SOURCE IS INOPERATIVE

Test Step	Result / Action to Take
E1 CHECK VOLTAGE TO THE SINGLE ILLUMINATION SOURCE	Yes GO to E2 . No REPAIR the circuit. TEST the system for normal operation.
Disconnect: Inoperative Illumination Source. Place the headlamp switch in the ON position. Rotate the instrument panel dimmer switch to the full illumination position. Measure the voltage between the inoperative illumination source, circuit 19 (LB/RD), harness side and ground. Is the voltage greater than 10 volts?
E2 CHECK SINGLE ILLUMINATION SOURCE GROUND	Yes INSTALL a new component in question. TEST the system for normal operation. No REPAIR the circuit. TEST the system for normal operation.
Measure the resistance between inoperative illumination source, circuit 1205 (BK), harness side and ground. Is the resistance less than 5 ohms?

Instrument Cluster Bulb

Removal and Installation

1. Remove the instrument cluster. For additional information, refer to Section.

2. Remove the necessary instrument cluster bulbs by rotating the bulb one quarter turn counterclockwise and lifting straight out of the instrument cluster.

3. To install, reverse the removal procedure.

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