Circuit Description
This diagnostic test functions on the assumption that a sudden decrease in non-drive, rear, wheel speed must be caused by a brake application. Non-drive wheel speed and stop lamp switch status are supplied to the PCM through serial data from the Electronic Brake and Traction Control Module (EBTCM). If there is a 6 mph or greater decrease of non-drive wheel speed in 0.4 seconds and a transition of the contacts at the TCC brake switch or stop lamp switch without a transition of the extended travel contacts of the TCC/antilock brake switch, DTC P1575 is set.
Conditions for Setting the DTC
Test Conditions
| • | DTCs P0703, P1574 and P1604 not set. |
| • | Traction control and antilock brake systems have not failed |
| • | Traction control and antilock brake systems are not active. |
| • | Non-drive wheel speed goes above 20 mph and then doesn't go below 4 mph. |
Failure Condition
A 6 MPH or greater decrease in non-drive wheel speed in 0.4 second and TCC brake switch or Stop/BTSI/Cruise brake switch indicating brakes applied and no transition is noticed in the extended travel contacts of the TCC brake switch indicating brakes applied.
Action Taken When the DTC Sets
| • | PCM disables cruise control. |
| • | PCM will set the extended travel brake switch status to not applied. |
| • | The Malfunction Indicator Lamp (MIL) will not illuminate. |
| • | The PCM will command a message to be displayed. |
| • | The PCM may record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records. |
Conditions for Clearing the Message/DTC
| • | The PCM will turn the message OFF after one run and pass of the diagnostic test. |
| • | A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test. |
| • | A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail. |
| • | Use a scan tool to clear DTCs. |
| • | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation. |
Diagnostic Aids
The operating conditions as well as the state of the extended travel brake switch circuit will be stored when the DTC was set.
Reviewing the Failure Rec. may help diagnose an intermittent failure by showing how long ago and under what conditions the DTC set.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Section 5, Brakes with Traction Control System (TCS), DTC 72 | Go to A Powertrain On Board Diagnostic (OBD) System Check |
