Pinpoint Test A: The Control Illumination Is Inoperative
- A1 CHECK THE EXTERIOR LAMPS
- Place the headlamp switch in the ON position.
- Do the exterior lamps illuminate?
- Yes : GO to A2.
- No : REFER to EXTERIOR LIGHTING to continue diagnosis of the exterior lamps.
- A2 CHECK THE HEADLAMP SWITCH
- Place the headlamp switch in the OFF position.
- Disconnect: Headlamp Switch.
- Carry out the headlamp switch component test. Refer to MAIN LIGHT SWITCH (11654), EXTERIOR LAMPS for component testing.
- Is the headlamp switch OK?
- Yes : GO to A3.
- No : INSTALL a new headlamp switch. REFER to EXTERIOR LIGHTING . TEST the system for normal operation.
- A3 CHECK CIRCUIT 14 (BN) FOR VOLTAGE
- Connect: Headlamp Switch C205a.
- Turn the headlamp switch to the parking lamps ON position.
- Measure the voltage between the headlamp switch C205b pin 6, circuit 14 (BN), harness side and ground.
- Is the voltage greater than 10 volts?
- Yes : GO to A4.
- No : REPAIR the circuit. TEST the system for normal operation.
- A4 CHECK CIRCUIT 57 (BK) FOR AN OPEN
- Turn the headlamp switch OFF.
- Measure the resistance between the headlamp switch C205b pin 4, circuit 57 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
- Yes : GO to A5.
- No : REPAIR the circuit. TEST the system for normal operation.
- A5 CHECK THE ILLUMINATION CIRCUIT BETWEEN THE INSTRUMENT CLUSTER AND THE HEADLAMP SWITCH FOR AN OPEN
- Disconnect: Instrument Cluster C220a.
- For Expedition, measure resistance between the instrument cluster C220a pin 6, circuit 19 (LB/RD), harness side and the instrument panel dimmer switch C205b pin 1, circuit 19 (LB/RD), harness side.
For Navigator, measure the resistance between the instrument cluster C220a pin 6, circuit 505 (GY/YE), harness side and the instrument panel dimmer switch C205b pin 1, circuit 505 (GY/YE), harness side.
- Is the resistance less than 5 ohms?
- Yes
: If Expedition, INSTALL a new instrument panel dimmer switch. REFER to INSTRUMENT PANEL DIMMER SWITCH in this section. TEST the system for normal operation.
If Navigator, GO to A6.
- No : REPAIR the circuit in question. TEST the system for normal operation.
- Disconnect: Instrument Cluster C220a.
- A6 CHECK GROUND CIRCUIT TO INSTRUMENT CLUSTER
- Turn the headlamp switch off.
- Measure the resistance between the instrument cluster C220a pin 9, circuit 676 (PK/OG), harness side and ground; and between the instrument cluster C220a pin 22, circuit 676 (PK/OG), harness side and ground.
- Is the resistance less than 5 ohms?
- Yes : GO to A7.
- No : REPAIR the circuit. TEST the system for normal operation.
- A7 CHECK ILLUMINATION VOLTAGE TO THE INSTRUMENT CLUSTER
- Connect: Instrument Panel Dimmer Switch C205b.
- Disconnect: Instrument Cluster C220a.
- Turn the headlamp switch to the parking lamps ON position.
- Rotate the instrument panel dimmer switch to the full illumination position.
- Measure the voltage between the instrument cluster C220a pin 6, circuit 505 (GY/YE), harness side and ground.
- Is the voltage greater than 10 volts?
- Yes : GO to A8
- No : INSTALL a new instrument panel dimmer switch. REFER to INSTRUMENT PANEL DIMMER SWITCH . TEST the system for normal operation.
- A8 CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION
- Disconnect all the instrument cluster connectors.
- Check for:
- corrosion
- pushed-out pins
- Connect all the instrument cluster connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
- Yes : INSTALL a new instrument cluster. REFER to INSTRUMENT CLUSTER . TEST the system for normal operation.
- No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.