Refer to Engine Controls Schematics
Cruise Control Module, EBCM and VSS
.
Circuit Description
This diagnostic test checks for a traction control system Desired Torque signal failure to the PCM. The PCM sends 12 volts on the Desired Torque circuit to the electronic brake and traction control module (EBTCM). The EBTCM then rapidly switches this CKT to ground creating a pulse width modulated (PWM) frequency signal to request a specific amount of torque reduction during a traction control event. If this PWM signal is not received by the PCM for 3 seconds, DTC P1571 is set.
Conditions for Running the DTC
| • | DTC P1602 is not set |
| • | The traction control has not failed |
| • | The engine speed is more than 500 RPM for 20 seconds. |
Conditions for Setting the DTC
A PWM frequency signal is not received on the Desired Torque circuit for 3 seconds.
Action Taken When the DTC Sets
| • | The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
| • | PCM disables first gear starts. |
| • | Transaxle shift adapts are maintained at current levels. |
Conditions for Clearing the MIL/DTC
| • | A History DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | The current DTC will clear when the diagnostic runs and does not fail. |
| • | Use a scan tool in order to clear the MIL diagnostic trouble code. |
| • | Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module Description , Clearing Diagnostic Trouble Codes. |
Diagnostic Aids
Notice: Use the connector test adapter kit J 35616-A for any test that
requires probing the following items:
• The PCM harness connectors • The electrical center fuse/relay cavities • The component terminals • The component harness connector
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
2 |
Is the voltage near the specified value? | 12 V | ||||||||
3 | Check for poor connections or terminal tension at the EBTCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Was a problem found and corrected? | -- | ||||||||
4 |
Was a problem found and corrected? | -- | ||||||||
5 | Check for poor connections or terminal tension at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Was a problem found and corrected? | -- | ||||||||
6 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |||||||
7 | Replace the EBTCM. Refer to Electronic Brake and Traction Control Module Replacement . Is the action complete? | -- | -- | |||||||
8 |
Does the scan tool indicate that this test ran and passed? | -- | System OK |
