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

BHE090366900W03

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.