Inspection Procedure 5

INSPECTION PROCEDURE 5: No Sound. [Vehicles with audio amplifier]

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 Tools:
- MB991223: Harness set
- MB992006: Extra Fine Probe

STEP 1. Check audio amplifier connector C-114 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Is audio amplifier connector C-114 in good condition?

YES : Go to Step 2.

NO : Repair or replace the component(s). The speakers should sound.

STEP 2. Measure the voltage at audio amplifier connector C-114 in order to check the battery circuit of power supply system to the audio amplifier.







1. Disconnect audio amplifier connector C-114, 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 3.

STEP 3. Check the wiring harness between audio amplifier connector C-114 (terminal 5, 15 and 16) and the battery.










NOTE: Also check intermediate connector C-24 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connectors C-24 is damaged, repair or replace the connector.

Q: Is the wiring harness between audio amplifier connector C-114 (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-114 in order to check the ground circuit to the audio amplifier.







1. Disconnect audio amplifier connector C-114, 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 6.

NO : Go to Step 5.

STEP 5. Check the wiring harness between audio amplifier connector C-114 (terminal 4, 11 and 12) and ground.







Q: Is the wiring harness between audio amplifier connector C-114 (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 6. Check radio and CD player with CD changer connector C-119 and audio amplifier connector C-115 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Are radio and CD player with CD changer connector C-119 and audio amplifier connector C-115 in good condition?

YES : Go to Step 7.

NO : Repair or replace the component(s). The door speaker (LH) should sound.

STEP 7. Check the wiring harness between radio and CD player with CD changer connector C-119 (terminals 21, 22, 23, 25, 26, 32, 33, 34, 35, 36 and 37) and audio amplifier connector C-115 (terminals 24, 34, 27, 22, 21, 31, 26, 32, 25, 29, and 28).







Q: Do the speakers sound normally?

YES : The procedure is complete.

NO : Replace the audio amplifier.