For 1990-2009 cars

Step | Action | Value | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Radio/Audio System Schematics Connector End View Reference: Entertainment Connector End Views
1 | Did you review the Description and Operation and perform the necessary inspections? | -- | Go to Step 2 | Go to Radio/Audio System Description and Operation
2 | Turn the ignition ON and the radio ON. Does the system operate normally? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3
3 | Inspect the radio connector for poor or loose connection. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 4
4 | Test for an open or high resistance in the battery positive voltage circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | 12 V | Go to Step 20 | Go to Step 5
5 | Test for an open or high resistance in the accessory voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | 12 V | Go to Step 20 | Go to Step 6
6 | Test for an open or high resistance in the ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Ground Potential | Go to Step 20 | Go to Step 7
7 | Is the vehicle equipped with RPO UE1 OnStar®? | -- | Go to Step 8 | Go to Step 11
8 | Disconnect the 12-way radio connector. Does the system operate normally? | -- | Go to Step 9 | Go to Step 11
9 | Check for a short to ground on the OnStar mute circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 10
10 | Replace the OnStar® VCIM. Refer to Communication Interface Module Replacement in Cellular Communication. Is the repair complete? | -- | Go to Step 20 | --
11 | Is the vehicle equipped with an amplifier (RPO WBM)? | -- | Go to Step 12 | Go to Step 17
12 | Measure the voltage at the amplifier 24-way connector radio on the amplifier control circuit. Is the measured voltage equal to the specified value? | 12 V with key ON | Go to Step 14 | Go to Step 13
13 | Test for an open or high resistance in the radio on the amplifier control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 14
14 | Test for an open or high resistance in the battery positive voltage circuit to the amplifier. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | 12 V at all times | Go to Step 20 | Go to Step 15
15 | Test for an open or high resistance in the ground circuit to the amplifier. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Ground potential | Go to Step 20 | Go to Step 16
16 |

1. The amplifier is disconnected.
2. The radio is ON at maximum volume.
3. Using the DVOM, measure the AC voltage between the LF (+) and the LF (-) circuits at the amplifier connector.

Is the voltage equal to or greater than the specified value?

0.50 V AC

Go to Step 18

Go to Step 17

17 | Disconnect the radio 24-way connector and test for a short to power or a short to ground on all the speaker output circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 19
18 | Replace the amplifier. Refer to Radio Speaker Amplifier Replacement . Is the repair complete? | -- | Go to Step 20 | --
19 | Replace the radio. Refer to Radio Replacement . Is the repair complete? | -- | Go to Step 20 | --
20 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2