Inspection Procedure 5

INSPECTION PROCEDURE 5: No Sound. [Vehicles with Audio Amplifier]














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). 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.





- Check the wiring harness for open circuit and short circuit.





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 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). 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.





- Check the ground wire for open circuit.

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). Harness Connector Inspection.

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).





- Check the wiring harness for open circuit and short circuit.

Q. Do the speakers sound normally?

YES The procedure is complete.

NO Repair or replace the audio amplifier.