Refer to
DLC, Instrument Panel, Engine Compartment Fuse Center
.
Circuit Description
The PCM uses the serial data line (CKT 800) to communicate with various other components and systems within the vehicle. If the PCM does not receive data from the Electronic Brake and Traction Control Module (EBTCM), the PCM will store DTC P1573 indicating loss of communication with the ABS/TCS system.
Conditions for Setting the DTC
PCM has detected a PCM - EBTCM communication error for 10 seconds.
Action Taken When the DTC Sets
| • | The PCM will not be able to communicate with the EBTCM. This will cause the EBTCM to set ABS DTC 75, disable traction control, and illuminate the TRACTION OFF lamp. |
| • | The PCM will not illuminate the Malfunction Indicator Lamp (MIL). |
| • | The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data. |
Conditions for Clearing the MIL/DTC
| • | A history DTC P1573 will clear after 40 consecutive warm-up cycles have occurred without a fault. |
| • | DTC P1573 can be cleared by using the scan tool Clear Info. |
Diagnostic Aids
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation.
Check for the following conditions:
| • | Poor Connection or Damaged Harness - Inspect vehicle wiring harness, for an open or short to ground in CKT 800, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness. |
| • | Intermittent Test - Observe ABS data on the scan tool while moving harness and related connectors. Refer to UART Data Line in Electrical Diagnosis for a complete mechanization of CKT 800 and devices using the UART serial data line. If failure is induced, the scan tool data will stop updating. This may help to isolate the location of the malfunction. |
If the above items have been checked and no problem is found but DTC P1573 continues to set, replace the PCM.
Reviewing the Fail Records vehicle mileage after the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic System Check performed? | -- | Go to the Powertrain OBD System Check | |
Attempt to select ABS data with the scan tool. Can ABS data be displayed? | -- | |||
3 |
Was a problem found? | -- | ||
4 | Ignition OFF. Disconnect the EBTCM. Ignition ON. Using a DVM, measure voltage between the serial data circuit at the EBTCM harness connector and ground. Does voltage constantly vary between the specified values? | 0.0-5.0V | Go to UART Data Line in Electrical Diagnosis section 8A | |
5 | Check the UART serial data circuit for a poor connection at the PCM If a problem is found, repair as necessary. Refer to Repair Procedures in Electrical Diagnosis Section 8A. Was a problem found? | -- | Go to Diagnostic Aids | |
6 | Check the UART serial data circuit for a poor connection at the EBTCM If a problem is found, repair as necessary. Refer to Repair Procedures in Electrical Diagnosis Section 8A. Was a problem found? | -- | ||
7 | Replace the EBTCM. Is Action complete? | -- | -- | |
8 |
Does scan tool indicate DTC P1573 failed? | -- | Repair complete |
