Pinpoint Test Q : DTC U0151, U0452: Notes

WARNING: This page is about a different car, the 2017 Lincoln Navigator and 2017 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

Refer to Vehicle Dynamic Systems , for schematic and connector information.

Normal Operation and Fault Conditions

The ABS module uses information received from several sensors (wheel speed sensors, steering wheel rotation sensor, stability/traction control system sensors, etc.) to determine if vehicle stability, traction or roll warrants ESC or RSC ® interaction. If a stability or traction event is going to occur, the ABS module adjusts the brake torque at specific wheels and the PCM reduces engine torque to help make the vehicle more stable. Once the ABS module has determined the stability or traction event has been corrected, it returns the brake and engine torque to normal and continues to monitor the vehicle. DTCs set in the ignition cycle can only be cleared by cycling the ignition off and on once the fault has been corrected. The RCM measures the yaw rate and vehicle acceleration, then sends the signal through a secondary, private HS-CAN to the ABS module. The ABS module uses this information for AdvanceTrac ® and RSC ® system operation. The ABS module also compares this information to other information it receives from other sensors (brake pedal input, steering wheel) to determine how valid the information is and to determine if an instability event is about to occur.

The RCM and the ABS module communicate along a secondary, private HS-CAN. An open circuit or a short to power or ground on any one of these circuits causes the ABS module to set a DTC. Also, if the RCM is not mounted in the correct position, with the electrical connector facing the driver-side of the vehicle, the ABS module also sets DTCs.

DTC Description	Fault Trigger Condition
U0151 - Lost Communication with Restraints Control Module (RCM) U0452 - Invalid Data Received from RCM	The RCM uses a dedicated communication bus to send information to the ABS module. If, during normal operation, the ABS module does not receive any information from the RCM for more than 250 milliseconds, DTC U0151 or U0452 sets. U0151 monitors both the public HS-CAN and the private HS-CAN circuits. If the ABS module does not receive the RCM serial number, over the public HS-CAN, DTC U0151 sets. DTC U0151 also sets if the sensor data is not received over the private HS-CAN from the RCM.

DTC Description

Fault Trigger Condition

U0151 - Lost Communication with Restraints Control Module (RCM)
U0452 - Invalid Data Received from RCM

The RCM uses a dedicated communication bus to send information to the ABS module. If, during normal operation, the ABS module does not receive any information from the RCM for more than 250 milliseconds, DTC U0151 or U0452 sets. U0151 monitors both the public HS-CAN and the private HS-CAN circuits. If the ABS module does not receive the RCM serial number, over the public HS-CAN, DTC U0151 sets. DTC U0151 also sets if the sensor data is not received over the private HS-CAN from the RCM.

Possible Causes

Wiring, terminals or connectors
RCM
ABS module