U1040 Loss of ABS Class 2 Serial Data COM

DTC U1040 Loss of ABS Class 2 Serial Data COM:

DTC U1040 Loss of ABS Class 2 Serial Data COM:

CIRCUIT DESCRIPTION
The BCM receives a state of health message from the Electronic Brake Traction Control Module (EBTCM) through the Class II serial data link.

CONDITIONS FOR SETTING THE DTC
The BCM does not receive a state of health message from the EBTCM.

ACTION TAKEN WHEN THE DTC SETS
^ The BCM stores DTC U1040 in memory.
^ The ABS indicator lamp turns on while the fault is present.

CONDITIONS FOR CLEARING THE DTC
^ DTC U1040 will clear as a current DTC U1040 and will set as a history DTC U1040 when the BCM detects a state of health message from the EBTCM.
^ A history DTC will clear after 100 consecutive ignition cycles if the condition for the fault is no longer present.
^ Using a scan tool.

DIAGNOSTIC AIDS
^ The following conditions may cause an intermittent malfunction to occur:
^ An intermittent open or short to ground in circuit 1122 or 1037.
^ Poor connections at the BCM or the EBTCM.
^ An intermittent open in the Splice Pack SP205.
^ The BCM may store DTC U1040 if certain diagnostics are performed between the EBTCM and the Data Link Connector (DLC).
^ DTC P1626 will set in the PCM when the ignition switch is on with the BCM disconnected. When BCM diagnostics and repairs are completed, refer to Powertrain Control Module Diagnosis in Engine Controls for additional information on PCM related DTCs.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
2. This step checks for an open in the Splice Pack SP205.
3. This step checks for a short to ground in circuit 1122.
4. This step checks for a short to B+ in circuit 1122.
5. This step checks for an open in circuit 1122.
11. This step determines whether the malfunction is intermittent or the EBTCM is faulty.