Radio controls, function interference (with colour display)
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Radio controls, function interference (with colour display)
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Circuit-/System description
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The radio/HVAC controls are powered via the battery and ground. The radio checks the current status of the controls via a monitor circuit. Communication between the radio control and the radio is via the CGI circuit.
Communication between HVAC control and the HVAC module is via a separate LIN circuit. The HVAC module communicates the status information to the radio via GMLAN for HVAC information display.
Reference diagram
Radio/Navigation System Schematics
Connector End View Reference
Component Connector End Views
Description and use
Radio/Audio System Description and Operation
Electric reference information
Diagnostic tool Reference
** Control Module Reference ** For diagnostic tool information
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System-/circuit verification
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1.
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Verify that no DTCs are present.
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3.
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Ignition ON, radio ON, check that the radio/HVAC panel's background lighting lights and that all controls function correctly.
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4.
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If some, but not all controls function correctly, replace the radio/HVAC controls.
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5.
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If not all functions function, see Circuit-/system test.
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1.
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Ignition OFF, disconnect the cable harness at A20 radio/HVAC control.
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2.
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Check for less than 10Ω between ground connection pin 17 and ground.
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3.
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If larger than stated range, test ground point circuit for high resistance.
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4.
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Check for less than 20Ω between data circuit pin 3 and ground.
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5.
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If higher than within stated range, test ground circuit for infinite /high resistance. If the circuit test is normal, replace A11 radio.
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6.
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Check that the test lamp between B+ circuit pin 10 and ground lights.
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7.
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If the test lamp does not light, check B+ circuit after short circuit or infinite/high resistance.
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8.
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Ignition ON, check that there is 2.4-2.75 V between the data circuit pin 1 and ground.
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9.
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If lower than stated range, test ground circuit for infinite /high resistance. If the circuit test is normal, replace A11 radio.
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10.
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If higher than stated range, check for short circuit. If the circuit test is normal, replace A11 radio.
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11.
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Check that there is 2.4-2.75 V between data circuit pin 2 and ground.
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12.
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If lower than stated range, check for short circuit or infinite/high resistance. If the circuit test is normal, replace the A11 radio.
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13.
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If higher than stated range, check for short circuit. If the circuit test is normal, replace the A11 radio.
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14.
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Check that there is less than 1 V between wake-up signal pin 4 and ground.
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15.
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If higher than stated range, check for short circuit. If the circuit test is normal, replace the A11 radio.
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16.
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Check that there is less than 1 V between reset signal pin 5 and ground.
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17.
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If higher than stated range, check for short circuit. If the circuit test is normal, replace the A11 radio.
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18.
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Ignition ON, reconnect the cable harness to A20 radio/HVAC control
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19.
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Disconnect the cable harness X1 for the A11 radio.
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20.
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Install a DMM between monitor signal pin 13 and ground.
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21.
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Ignition ON, check that DMM displays 4.5-5.5 V DC.
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22.
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If lower than stated range, check for short circuit or infinite/high resistance. If the circuit test is normal, replace the A20 radio/HVAC control.
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23.
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If higher than stated range, check for short circuit. If the circuit test is normal, replace the A20 radio/HVAC control.
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24.
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Press the switch on the radio. Check that DMM read off is temporarily below 1 V and returns to 4.5-5.5 V DC each time the switch is pressed
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25.
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If the stated value is not reached, replace the A20 radio/HVAC control.
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26.
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Check that there is 4.5-5.5 V between reset signal pin 27 and ground.
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27.
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If less than the stated range, check for short circuit or infinite/high resistance. If the circuit test is normal, replace the A20 radio/HVAC control.
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28.
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If higher than stated range, check for short circuit. If the circuit test is normal, replace the A20 radio/HVAC control.
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29.
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If all circuit tests are normal, reinstall the A20 radio/HVAC control and reconnect the cable harness.
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30.
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Ignition ON, radio ON, check that the radio/HVAC control's background lighting lights and that all functions function.
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31.
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If the radio/HVAC control still does not work, replace A11 radio.
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Carry out
Confirmation of diagnostic repair
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See
Control module, references
for radio or for complete radio control replacement, setup or programming
