Subaru Legacy 2002 Service Manual page 2417

DIAGNOSTICS CHART WITH SUBARU SELECT MONITOR
ABS (Diagnostics)
U: DTC 42 POWER SUPPLY VOLTAGE TOO LOW
S006583I72
DIAGNOSIS:
¼ Power source voltage of the ABSCM&H/U is low.
TROUBLE SYMPTOM:
¼ ABS does not operate.
WIRING DIAGRAM:
B4M2334
ABS-116