ABS Module Ignition Input On
Table of contents
U300E MERCURY Possible Causes
- Faulty Anti-Lock Brake System (ABS) Module
- Anti-Lock Brake System (ABS) Module harness is open or shorted
- Anti-Lock Brake System (ABS) Module circuit poor electrical connection
How do I fix code U300E MERCURY?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Tech Notes
- This DTC sets in continuous memory if the power mode message from the BCM indicates the ignition is ON, but the ignition voltage supplied to the ABS module is missing.
Cost of diagnosing the U300E MERCURY code
The cost of diagnosing the U300E MERCURY code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
U300E MERCURY Description
The Anti-Lock Brake System (ABS) Module, hydraulic pump and solenoid valves require an operating voltage that is between 10 and 17 volts. The ABS module receives this voltage from the BJB. The ABS module has a single ground circuit located in the engine compartment wiring harness. Excessive resistance or an open in one or more of these circuits, a discharged battery or a inoperative charging system results in the ABS module setting a DTC.
Internally to the ABS module, the ignition voltage supply circuit is used as a redundant back up for the battery voltage supply circuit in case the battery voltage supply circuit is interrupted. If the battery voltage supply circuit is interrupted, the ABS module immediately shuts off and does not enter the power latch mode. The module uses the power latch mode to write certain parameters (such as learned offsets numbers) to non-volatile memory. At the beginning of each ignition cycle, a counter value is increased by 1 after a specified vehicle speed has been reached and a specified time has elapsed. When the ABS module enters the power latch mode, this counter is reset to 0.
