INSPECTION PROCEDURE 2: No Sound. < Vehicles with Amplifier >: Diagnosis

Required Special Tool: 

• MB991223: Harness set

1. STEP 1. Measure at amplifier connector D-20 in order to check the battery circuit of power supply system to the amplifier. 
   1. Disconnect amplifier connector D-20, and measure at the wiring harness side.
      Fig 1: Identifying Radio and CD Player Connector D-20

      Courtesy of DAIMLERCHRYSLER CORPORATION
   2. Measure the voltage between terminal 7 and ground.
      • The measured value should be approximately 12 volts (battery positive voltage).
   3. Measure the voltage between terminal 17 and ground.
      • The measured value should be approximately 12 volts (battery positive voltage).

   Q: Are the voltages approximately 12 volts (battery positive voltage)? 

   YES  : Go to  Step 4.

   NO:  Go to Step 2.

   Fig 2: Measuring Voltage Between Terminal 17 And Ground

   Courtesy of DAIMLERCHRYSLER CORPORATION
2. STEP 2. Check amplifier connector D-20 for damage. 

   Q: Is amplifier connector D-20 in good condition? 

   YES  : Go to Step 3.

   NO:  Repair or replace the connector. Refer to , HARNESS CONNECTOR INSPECTION . The speakers should sound.

   Fig 3: Identifying Radio and CD Player Connector D-20

   Courtesy of DAIMLERCHRYSLER CORPORATION
3. STEP 3. Check the wiring harness between amplifier connector D-20 (terminals 7 and 17) and fusible link (5). 
   Fig 4: Identifying Radio and CD Player Connector Fusible Link (5)

   Courtesy of DAIMLERCHRYSLER CORPORATION
   Fig 5: Identifying Radio and CD Player Connector D-20

   Courtesy of DAIMLERCHRYSLER CORPORATION
   NOTE: Also check intermediate connector C-209. If intermediate connector C-209 is damaged, repair or replace the connector as described in , HARNESS CONNECTOR INSPECTION .

   Q: Are the wiring harnesses between amplifier connector D-20 (terminals 7 and 17) and fusible link (5) in good condition? 

   YES  : There is no action to be taken.

   NO:  Repair the wiring harness(es). The speakers should sound.

   Fig 6: Identifying Radio and CD Player Connector C-209

   Courtesy of DAIMLERCHRYSLER CORPORATION
4. STEP 4. Measure at amplifier connector D-20 in order to check the ground circuit to the amplifier. 
   1. Disconnect amplifier connector D-20, and measure at the wiring harness side.
      Fig 7: Identifying Radio and CD Player Connector D-20

      Courtesy of DAIMLERCHRYSLER CORPORATION
   2. Measure the resistance between terminal 6 and ground by backprobing.
      • The measured value should be 2 ohms or less.
   3. Measure the resistance between terminal 16 and ground by backprobing.
      • The measured value should be 2 ohms or less.

   Q: Does the measured resistance value correspond with this range? 

   YES  : Go to  Step 7.

   NO:  Go to Step 5.

   Fig 8: Measuring Resistance Between Terminal 6 And Ground

   Courtesy of DAIMLERCHRYSLER CORPORATION
5. STEP 5. Check amplifier connector D-20 for damage. 

   Q: Is amplifier connector D-20 in good condition? 

   YES  : Go to Step 6.

   NO:  Repair or replace the connector. Refer to , HARNESS CONNECTOR INSPECTION . The speakers should sound.

   Fig 9: Identifying Radio and CD Player Connector D-20

   Courtesy of DAIMLERCHRYSLER CORPORATION
6. STEP 6. Check the wiring harness between amplifier connector D-20 and ground. 

   Q: Is the wiring harness between amplifier connector D-20 and ground in good condition? 

   YES  : There is no action to be taken.

   NO:  Repair the wiring harness. The speakers should sound.

   Fig 10: Identifying Radio and CD Player Connector D-20

   Courtesy of DAIMLERCHRYSLER CORPORATION
7. STEP 7. Check the DIN cable between radio, CD player and amplifier. 

   Q: Is the DIN cable in good condition? 

   YES  : Go to Step 8.

   NO:  Repair or replace the DIN cable. The speakers should sound.

8. STEP 8. Replace the radio and CD player. 

   Q: Do the speakers sound normally? 

   YES  : There is no action to be taken.

   NO:  Repair or replace the amplifier. The speakers should sound.