Inspection Procedure 5

INSPECTION PROCEDURE 5: No Sound.

Audio Amplifier Power Supply Circuit Part 1:

Audio Amplifier Power Supply Circuit Part 2:

CIRCUIT OPERATION
Power is supplied from the battery directly to the audio amplifier.

TECHNICAL DESCRIPTION (COMMENT)
The cause is probably a faulty audio amplifier power supply circuit system.

TROUBLESHOOTING HINTS
- Damaged wiring harness or connector.
- Malfunction of the audio amplifier.

DIAGNOSIS

Required Special Tool:
- MB991223: Harness set

STEP 1. Measure the voltage at audio amplifier connector C-113 in order to check the battery circuit of power supply system to the audio amplifier.




1. Disconnect audio amplifier connector C-113, and measure at the wiring harness side.




2. Measure the voltage between terminal 5 and ground.
- The voltage should measure approximately 12 volts (battery positive voltage).

3. Measure the voltage between terminal 15 and ground.
- The voltage should measure approximately 12 volts (battery positive voltage).

4. Measure the voltage between terminal 16 and ground.
- The voltage should measure approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approximately 12 volts (battery positive voltage)?

YES: Go to Step 4.

NO: Go to Step 2.




STEP 2. Check audio amplifier connector C-113 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is audio amplifier connector C-113 in good condition?

YES: Go to Step 3.

NO: Repair or replace the component(s). Refer to Harness Connector Inspection. The speakers should sound.




STEP 3. Check the wiring harness between audio amplifier connector C-113 (terminal 5, 15 and 16) and the battery.






NOTE: Also check intermediate connector C-29 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connectors C-29 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between audio amplifier connector C-113 (terminal 5, 15 and 16) and the battery in good condition?

YES: There is no action to be taken.

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

STEP 4. Measure the resistance at audio amplifier connector C-113 in order to check the ground circuit to the audio amplifier.




1. Disconnect audio amplifier connector C-113, and measure at the wiring harness side.




2. Measure the resistance between terminal 4 and ground.
- The resistance should be 2 ohms or less.

3. Measure the resistance between terminal 11 and ground.
- The resistance should be 2 ohms or less.

4. Measure the resistance between terminal 12 and ground.
- The resistance should be 2 ohms or less.

Q: Is the measured resistance 2 ohms or less?

YES: Go to Step 7.

NO: Go to Step 5.




STEP 5. Check audio amplifier connector C-113 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is audio amplifier connector C-113 in good condition?

YES: Go to Step 6.

NO: Repair or replace the component(s). Refer to Harness Connector Inspection. The speakers should sound.




STEP 6. Check the wiring harness between audio amplifier connector C-113 (terminal 4, 11 and 12) and ground.

Q: Is the wiring harness between audio amplifier connector C-113 (terminal 4, 11 and 12) and ground in good condition?

YES: There is no action to be taken.

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




STEP 7. Check radio, CD player and CD changer connector C-134 and audio amplifier connector C-114 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are radio, CD player and CD changer connector C-134 and audio amplifier connector C-114 in good condition?

YES: Go to Step 8.

NO: Repair or replace the component(s). Refer to Harness Connector Inspection. The door speaker (LH) should sound.




STEP 8. Check the wiring harness between CD player and CD changer connector C-134 (terminals 21, 22, 23, 25, 26, 32, 34, 35 and 37) and audio amplifier connector C-114 (terminals 24, 34, 27, 22, 21, 31, 32, 25 and 28).

Q: Do the speakers sound normally?

YES: The procedure is complete.

NO: Repair or replace the audio amplifier.