Test A: The Message Center Is Not Operating Correctly

PINPOINT TEST A: THE MESSAGE CENTER IS NOT OPERATING CORRECTLY

Normal Operation
The message center functionality is controlled through the message center switch, which is hardwired to the instrument cluster through input circuit CMC29 (GN/VT) and return circuit RMC27 (WH/BN). There are 3 message center switch buttons with each button operating a switch that uses different resistance values. The instrument cluster sends out a reference voltage to the message center switch on the input circuit and monitors the voltage drop when a message center switch button is pressed. The voltage drop will vary depending upon the resistance of each button, providing a specific indication to the instrument cluster which switch is pressed.

DTC B1205 (EIC Switch-1 Assembly Circuit Failure) - is a continuous and on-demand DTC that sets in the instrument cluster when the instrument cluster detects any of the message center switch buttons stuck closed for more than 120 seconds continuously or during the on-demand self-test.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Message center switch (part of the steering wheel audio control)
- Instrument cluster

A1-A4:

A4-A5:

A6-A8:

A9-A10: