Inspection Procedure 2
INSPECTION PROCEDURE 2: No Sound.
CIRCUIT OPERATION
Power is supplied from fusible link (4) to the amplifier.
TECHNICAL DESCRIPTION (COMMENT)
The cause is probably a faulty amplifier power supply circuit system.
TROUBLESHOOTING HINTS
- Damaged harness wire or connector.
- Damaged DIN cable.
- Malfunction of the amplifier.
- Malfunction of the radio, tape player, CD player and CD auto changer.
DIAGNOSIS
Required Special Tool:
- MB991223: Harness set
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.
2. Measure the voltage between terminal 7 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
- 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.
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.
STEP 3. Check the wiring harness between amplifier connector D-20 (terminals 7 and 17) and fusible link (5).
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.
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.
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.
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.
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.
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.
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.