Pinpoint Test AF: The Message Center Is Not Operating Correctly
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test AF: The Message Center Is Not Operating Correctly
Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information. Diagrams By Number
Normal Operation
The message center is located in the center of the Instrument Cluster (IC) between the tachometer and the speedometer in the Vacuum Fluorescent (VF) display area. The message center is integral to the IC and uses the same RUN/START and keep alive voltage supply as the IC.
The message center functionality is controlled through the message center switch, which is hardwired to the IC through the input and the return circuits. There are 3 message center switch buttons with each button using a different resistance value. The IC sends out a reference voltage to the message center switch on the input circuit and monitors the input voltage when a message center switch button is pressed. The input voltage will vary depending upon the resistance of each button, providing a specific indication to the IC which switch is pressed.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Message center switch
- IC
PINPOINT TEST AF: THE MESSAGE CENTER IS NOT OPERATING CORRECTLY
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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AF1 CHECK THE ODOMETER OPERATION
- Ignition ON.
- Observe the odometer display in the message center.
- Is the odometer displayed?
Yes
If the display is blank, PRESS the INFO button to see if the message center was previously set to the blank display. If the display remains blank or if the INFO, SETUP or RESET buttons are inoperative, GO to AF2.
If individual messages are inoperative, GO to Symptom Chart - Information And Message Center. Instrumentation, Message Center, and Warning Chimes
No
GO to Pinpoint Test H. Pinpoint Test H: The Odometer Is Inoperative
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AF2 CHECK THE MESSAGE CENTER SWITCH PIDs
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger .
- Select and monitor IC information switch (INFOSW) PID, setup switch (SETUPSW) PID and reset switch (RES_SW) PID, while pressing each message center switch button (INFO, SETUP and RESET).
- Does the PID agree with the button position?
Yes
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
No
GO to AF3.
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AF3 CHECK THE MESSAGE CENTER SWITCH SIGNAL AND RETURN CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: IC C220 .
- Ignition ON.
- Measure the voltage between the IC C220-19, circuit CMC29 (GN/VT), harness side and ground; and between the IC C220-20, circuit VMC29 (YE), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit in question. TEST the system for normal operation.
No
GO to AF4.
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AF4 CHECK THE MESSAGE CENTER SWITCH SIGNAL CIRCUIT FOR AN OPEN AND SHORT TO GROUND
- Ignition OFF.
- Disconnect: Message Center Switch C253 .
- Measure the resistance between the IC C220-19, circuit CMC29 (GN/VT), harness side and the message center switch C253-3, circuit CMC29 (GN/VT), harness side; and between the IC C220-19, circuit CMC29 (GN/VT), harness side and ground.
- Is the resistance less than 5 ohms between the IC and the message center switch, and greater than 10,000 ohms between the IC and ground?
Yes
GO to AF5.
No
REPAIR circuit CMC29 (GN/VT) for an open or short to ground. TEST the system for normal operation.
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AF5 CHECK THE MESSAGE CENTER SWITCH RETURN CIRCUIT FOR AN OPEN AND SHORT TO GROUND
- Measure the resistance between the IC C220-20, circuit VMC29 (YE), harness side and the message center switch C253-2, circuit VMC29 (YE), harness side; and between the IC C220-20, circuit VMC29 (YE), harness side and ground.
- Is the resistance less than 5 ohms between the IC and the message center switch, and greater than 10,000 ohms between the IC and ground?
Yes
GO to AF6.
No
REPAIR circuit VMC29 (YE) for an open or short to ground. TEST the system for normal operation.
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AF6 CHECK FOR VOLTAGE FROM THE IC
- Connect: IC C220 .
- Ignition ON.
- Measure the voltage between the message center switch C235-3, circuit CMC29 (GN/VT), harness side and the message center switch C253-2, circuit VMC29 (YE), harness side and ground.
- Is the voltage approximately 5 volts or greater?
Yes
INSTALL a new message center switch. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
No
GO to AF7.
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AF7 CHECK FOR CORRECT IC OPERATION
- Disconnect the IC connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the IC connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). 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.
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