NO.1 ALC (AUTOMATIC LEVEL CONTROL) DO NOT OPERATE. (ABS HU/CM OPERATES NORMALLY.)

B3E090366900W03

1

ALC (automatic level control) do not operate. (ABS HU/CM operates normally.)

TROUBLESHOOTING HINTS

• Malfunction in vehicle speed signal line of audio unit.
- Audio unit malfunction
- ABS HU/CM malfunction
- Malfunction in wiring harness between audio unit and ABS HU/CM

Diagnostic procedure

STEP

INSPECTION

ACTION

1
• Is ALC function operating?
Yes
Go to next step.
No
Make ALC function operate, then go to Step 5.
2
• Inspect DTC of PCM.
• Is DTC P0500 (VSS circuit malfunction) displayed?
Yes
Go to applicable DTC inspection.
No
Go to next step.
3*
• Disconnect audio unit connector (24-pin) and ABS HU/CM connector (28-pin).
• Is there continuity between audio unit connector (24-pin) terminal 1I and ABS HU/CM connector (28-pin) terminal 1V?
Yes
Go to next step.
No
Repair wiring harness between audio unit and ABS HU/CM, then go to Step 5.
4
• Inspect wiring harness between audio unit connector (24-pin) terminal 1I and ABS HU/CM connector (28-pin) terminal 1V for short to ground.
• Is there short to ground?
Yes
Repair wiring harness between audio unit and ABS HU/CM, then go to next step.
No
Replace base unit, then go to next step.
5
• Does ALC operate normally?
Yes
Complete troubleshooting, then explain repairs to customer.
No
Recheck malfunction symptoms, then repeat from Step 1 if malfunction recurs.