GM Service Manual Online
For 1990-2009 cars only

Radio Poor Reception Fixed Mast

Step

Action

Value(s)

Yes

No

1

Did you review the Radio/Audio System Operation?

--

Go to Step 2

Go to Radio/Audio System Operation

2

  1. Turn ON the ignition, with the engine OFF.
  2. Turn ON the radio.
  3. Tune the radio to a known strong AM station, then tune to a known strong FM station.

Is the radio reception clear?

--

Go to Audio System Troubleshooting Hints

Go to Step  3

3

Inspect for the following:

    • Radio antenna coaxial cable interconnects for corrosion and proper connection.
    • Proper connection at the antenna.
    • Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step  12

Go to Step  4

4

  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable.
  3. Remove the radio. Refer to Radio Replacement for service procedure.
  4. Zero the digital multi-meter (DMM).
  5. Measure the resistance between the negative battery cable and the radio antenna coaxial ground at the radio.

Is the resistance within the specified value?

0 - 0.6 ohms

Go to Step 5

Go to Step  6

5

  1. Grasp the antenna mast.
  2. Monitor the DMM and wiggle the antenna mast.

Does the DMM display intermittent continuity?

--

Go to Step  6

Go to Step  7

6

Inspect the antenna base for a proper connection to the body ground.

Did you find and correct the condition?

--

Go to Step  12

Go to Step  8

7

  1. Remove the radio antenna coxial lead-in connector from the radio.
  2. Measure the resistance between the radio antenna coaxial lead-in (center conductor) connector and the antenna mast with a DMM. Refer to Circuit Testing in Wiring Systems.

Is the measured resistance less than the specified values?

RG-58/RG-59 Coax: 0.2 ohms

RG-62/RG-62M Coax: 3.5 ohms

Go to Step  9

Go to Step  10

8

Inspect the ground connection from the battery negative cable to the body. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step  12

Go to Step  10

9

  1. Test for continuity between the antenna coxial cable center conductor and metal case.
  2. Test at the opposite end of the antenna cable also.

Did you measure continuity?

--

Go to Step  11

Go to Step  10

10

Inspect the radio antenna coaxial cable interconnects for a poor connection or corrosion. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step  12

Go to Step  11

11

Repair or replace the radio antenna coaxial cable circuit.

Did you complete the repair or replacement?

--

Go to Step  12

--

12

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Audio System Troubleshooting Hints

Radio Poor Reception Rear Glass

Step

Action

Value(s)

Yes

No

1

Did you review the Radio/Audio System Operation?

--

Go to Step 2

Go to Radio/Audio System Operation

2

  1. Turn ON the ignition, with the engine OFF.
  2. Turn ON the radio.

  3. Tune the radio to a known strong AM station then to a known strong FM station.

Is the radio reception clear?

--

Go to Audio System Troubleshooting Hints

Go to Step 3

3

  1. Inspect the antenna coxial cable for proper connections at the antenna amplifier module.
  2. Inspect both harness connectors at the antenna amplifier module for proper connections.
  3. 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 17

Go to Step 4

4

Does poor or no reception occur only on AM?

--

Go to Step 5

Go to Step 6

5

  1. Turn OFF the ignition.
  2. Disconnect the antenna amplifier module harness connector C1.
  3. Turn ON the ignition, with the engine OFF.
  4. Turn ON the radio.
  5. Connect a test lamp between connector C1 terminal 2 and ground.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 9

6

  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable.
  3. Remove the radio. Refer to Radio Replacement for service procedure.
  4. Important: Always zero out the DMM before taking a resistance measurement to ensure an accurate reading.

  5. Measure the resistance between the negative battery cable and the radio antenna coaxial ground at the radio.

Does the resistance measure greater than the specified value?

0.20 ohms

Go to Step 10

Go to Step 7

7

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

  1. Remove the antenna coxial cable from the radio and antenna amplifier module.
  2. Measure the resistance of the antenna cable center conductor between the radio and the antenna amplifier module.

Does the resistance measure greater than the specified values?

RG-58/RG-59  Coax: 0.20 ohms

RG-62/RG-62M  Coax: 3.5 ohms

Go to Step 11

Go to Step 8

8

  1. Test for continuity between the antenna coxial cable center conductor and metal case.
  2. Test at the opposite end of the antenna cable also.

Did you measure continuity?

--

Go to Step 14

Go to Step 12

9

Test the power antenna circuit for an open, short to ground or high resistance. Refer to Circuit Testing and Wiring Repairs in wiring repairs.

Did you find and correct the condition.

--

Go to Step 17

Go to Step 13

10

Test the antenna amplifier module case ground for an open, or high resistance. Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 14

11

  1. Test the antenna cable center conductor for an open or high resistance. Refer to Circuit Testing in Wiring Systems.
  2. Inspect the antenna coxial cable interconnects for a poor connection or corrosion. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 14

12

Inspect for poor connections at the antenna amplifier 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 17

Go to Step 15

13

Inspect for poor connections at 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 17

Go to Step 16

14

Replace the antenna coaxial cable.

Did you complete the replacement?

--

Go to Step 17

--

15

Replace the antenna amplifier module.

Did you complete the replacement?

--

Go to Step 17

--

16

Replace the radio. Refer to Radio Replacement for service procedure.

Did you complete the replacement?

--

Go to Step 17

--

17

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Audio System Troubleshooting Hints