NOTE: Before you troubleshoot, review the how to troubleshoot the electric parking brake system.
1. Problem verification:
Is DTC U3003-68 indicated?
YES
The failure is duplicated. Go to step 2.
NO
Intermittent failure, the system is OK at this time. Refer to intermittent failures troubleshooting. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the Freeze data/on-board snapshot.
2. Fuse check:
Are the fuses OK?
YES
The fuse is OK. Reinstall the fuse, then go to step 3.
NO
Replace the fuse. If the fuse blows again, repair a short to ground in the No. D2-5 (30 A) and/or No. D2-2 (30 A) fuses circuit.
3. Open wire check (+B EPB L, +B EPB R lines):
Electric parking brake control unit 30P connector
Is there battery voltage?
YES
The +B EPB L and +B EPB R wires are OK. Go to step 4.
NO
Repair an open or high resistance in the +B EPB L, +B EPB R wires between the electric parking brake control unit and the No. D2-2 (30 A) and/or No. D2-5 (30 A) fuses in the auxiliary under-dash fuse box A.
4. Open wire check (GND lines):
Electric parking brake control unit 30P connector
Is there 0.1 V or more?
YES
Repair an open in the GND wires between the electric parking brake control unit and body ground (G503).
NO
The GND wires are OK. Go to step 5.
5. Electric parking brake control unit check (update or substitution):
Is DTC U3003-68 indicated?
YES
Check for loose terminals and poor connections in the electric parking brake control unit 30P connector.
If the electric parking brake control unit was updated, substitute a known-good electric parking brake control unit and recheck. If the electric parking brake control unit was substituted and the symptom/indication is still present, replace the original electric parking brake control unit.
NO
If the electric parking brake control unit was updated, troubleshooting is complete. If the electric parking brake control unit was substituted, replace the original electric parking brake control unit.