Inspection Procedure 2
No Sound.Amplifier Power Supply Circuit:
CIRCUIT OPERATION
Power is supplied to the amplifier when the battery.
TECHNICAL DESCRIPTION (COMMENT)
The cause is probably a faulty amplifier power supply circuit system.
TROUBLESHOOTING HINTS
- Damaged wiring harness or connector.
- Damaged DIN cable.
- Malfunction of the amplifier.
- Malfunction of the radio and CD player.
DIAGNOSIS
Required Special Tool:
- MB991223: Harness set
STEP 1. Measure at amplifier connector D-27 by backprobing in order to check the battery circuit of power supply system to the amplifier.
1. Measure at amplifier connector D-27 without disconnecting the connector.
2. Measure the voltage between terminal 2 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
3. Measure the voltage between terminal 10 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
Q: Does the measured voltage correspond with this range?
YES: Go to Step 4.
NO: Go to Step 2.
STEP 2. Check amplifier connector D-27 for damage.
Q: Is amplifier connector D-27 in good condition?
YES: Go to Step 3.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. The speakers should sound.
STEP 3. Check the wiring harness between amplifier connector D-27 (terminal 10 and 2)and battery.
NOTE: Also check intermediate connector C-116 and C-117. If intermediate connectors C-116 or C-117 are damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Are the wiring harness between amplifier connector D-27 (terminal 10 and 2) and battery in good condition?
YES: There is no action to be taken.
NO: Repair the wiring harness. The speakers should sound.
STEP 4. Measure at amplifier connector D-27 by backprobing in order to check the ground circuit to the amplifier.
1. Measure at amplifier connector D-27 without disconnecting the connector.
2. Measure the resistance between terminal 1 and ground by backprobing.
- The measured value should be 2 Ohms or less.
3. Measure the resistance between terminal 9 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.
STEP 5. Check amplifier connector D-27 for damage.
Q: Is amplifier connector D-27 in good condition?
YES: Go to Step 6.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. The speakers should sound.
STEP 6. Check the wiring harness between amplifier connector D-27 (terminal 1 and 9) and ground.
Q: Are the wiring harness between amplifier connector D-27 (terminal 1 and 9) 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 the DIN cable between amplifier and radio and CD player.
Q: Are the DIN cable in good condition?
YES: Go to Step 8.
NO: Repair or replace the DIN cable. The speakers should sound.
STEP 8. Replace the radio and CD player.
Q: Is sound output normally from all the speakers?
YES: There is no action to be taken.
NO: Repair or replace the amplifier. The speakers should sound.