C1236: OBD-II code C1236 flags low battery/system voltage at the EBCM — ABS is disabled to protect the module and solenoids from unreliable operation.

Symptoms

• The ABS warning lamp, and often the traction and stability control lamps, come on during or shortly after a low-voltage event.
• The code frequently sets during cranking or on vehicles with a weak battery or alternator, then may clear once voltage returns to normal.
• ABS and stability control are disabled while the code is active, though standard hydraulic braking is unaffected.

Common causes

• A weak or failing battery that drops below the EBCM's minimum voltage threshold (typically around 10 V) during cranking or high accessory load.
• A failing alternator, worn brushes, or loose alternator drive belt causing charging system voltage to fall below spec at idle.
• Corroded battery terminals, loose ground straps, or a damaged main power feed to the EBCM adding excessive resistance in the supply path.

What to do?

Load-test the battery and confirm charging system output stays between 13.8 and 14.5 V at idle and at 2,000 rpm. Measure voltage at the EBCM main power feed with the ignition on — it should match battery voltage. Clean and torque battery terminals and inspect the main chassis ground straps. Replace battery or alternator as needed, then clear the code and retest.