GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Schematic Reference: Radio/Audio System Schematics

Connector Reference: Entertainment Connector End Views

1

Did you review the Radio/Audio System Description and Operation and perform the necessary inspections?

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Go to Step 2

Go to Symptoms - Entertainment

2

  1. Turn ON the ignition, with the engine OFF.
  2. Turn ON the radio.
  3. Tune the radio to several local AM stations then to several local FM stations.

Is the radio reception clear?

--

Go to Step 3

Go to Step 4

3

Turn ON the rear defogger.

Is the radio reception clear?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 5

4

Inspect for proper connections at the rear window antenna and the radio antenna module. 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 26

Go to Step 6

5

Connect the base of the rear defogger/antenna grid to chassis ground.

Does the reception improve?

--

Go to Step 13

Go to Step 12

6

Is there poor or no reception only on AM?

--

Go to Step 11

Go to Step 7

7

Is there poor or no reception only on FM?

--

Go to Step 12

Go to Step 8

8

  1. Turn OFF the ignition.
  2. Disconnect the radio antenna module connector C1.
  3. Turn ON the ignition, with the engine OFF.
  4. Turn ON the radio.
  5. Connect a test lamp between the antenna relay coil supply voltage circuit of the radio antenna module and a good ground.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 14

9

  1. Turn OFF the ignition.
  2. Remove the radio. Refer to Radio Replacement .
  3. Important:: Always zero the DMM before taking a resistance measurement to ensure an accurate reading.

  4. Measure resistance between the radio antenna connector ground and the radio antenna module ground.

Does the resistance measure greater than the specified value?

1.0 ohms

Go to Step 22

Go to Step 10

10

Important:: Always zero the DMM before taking a resistance measurement to ensure an accurate reading.

Measure resistance of the antenna cable center conductor between the radio and the radio antenna module.

Does the resistance measure greater than the specified value?

1.0 ohms

Go to Step 22

Go to Step 20

11

Testt the AM antenna grid for an open. Refer to Defogger Grid Lines Diagnosis in Stationary Windows.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 15

12

Test the rear defogger grid for an open. Refer to Defogger Grid Lines Diagnosis in Stationary Windows.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 16

13

Test the ground coil input circuit for a high resistance, open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 17

14

Test the antenna relay coil supply voltage circuit of the radio antenna module for a high resistance, open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 20

15

Test the AM antenna grid circuit between the radio antenna module and the AM antenna grid for a high resistance, open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 19

16

Test the FM antenna grid circuit between the radio antenna module and the FM antenna grid for a high resistance, open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 26

Go to Step 19

17

Inspect for poor connections at the harness connector of the ground coil. 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 26

Go to Step 21

18

Inspect for poor connections at the harness connector of the rear defogger grid. 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 26

Go to Step 23

19

Inspect for poor connections at the harness connector of the radio antenna module. 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 26

Go to Step 24

20

Inspect for poor connections at the harness connector of the radio. 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 26

Go to Step 25

21

Replace the ground coil. Refer to Antenna Module Coil Replacement .

Did you complete the replacement?

--

Go to Step 26

--

22

Replace the coax cable. Refer to Coaxial Cable Replacement .

Did you complete the replacement?

--

Go to Step 26

--

23

Replace the rear window. Refer to Rear Window Replacement in Stationary Windows.

Did you complete the replacement?

--

Go to Step 26

--

24

Replace the radio antenna module. Refer to Radio Antenna Module Replacement .

Did you complete the replacement?

--

Go to Step 26

--

25

Replace the radio. Refer to Radio Replacement .

Did you complete the replacement?

--

Go to Step 26

--

26

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2