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

id0903e1877700

1

ALC (automatic leveI contorol) do not operate. (DSC HU/CM operates normally.)

TROUBLESHOOTING HINTS

• Malfunction in vehicle speed signal line of audio unit.
– Audio unit malfunction
– DSC HU/CM malfunction
– Malfunction in wiring harness between audio unit and DSC 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 DSC HU/CM connector (34-pin).
• Is there continuity between audio unit connector (24-pin) terminal 1I and DSC HU/CM connector (34-pin) terminal AA?
Yes
Go to next step.
No
Repair wiring harness between audio unit and DSC HU/CM, then go to Step 5.
4
• Inspect wiring harness between audio unit connector (24-pin) terminal 1I and DSC HU/CM connector (34-pin) terminal AA for short to ground.
• Is there short to ground?
Yes
Repair wiring harness between audio unit and DSC 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.