Circuit Description
This diagnostic test functions on the assumption that a sudden decrease in the 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 (EBCM). If there is a 6 mph or more decrease of non-drive wheel speed during 0.4 second, and a transition of the torque converter clutch (TCC) contacts at the TCC brake switch or at the stop lamp switch without a transition of the extended travel contacts of the TCC brake, DTC P1575 is set.
Conditions for Running the DTC
| • | DTC P1574 is not set. |
| • | The traction control and antilock brake systems have not failed. |
| • | The traction control and antilock brake systems are not active. |
| • | The non-drive wheel speed goes above 32 km/h (20 mph) and then does not go below 6 km/h (4 mph). |
Conditions for Setting the DTC
A 10 km/h (6 mph) or more 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
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Diagnostic Aids
If the condition is intermittent, refer to Intermittent Conditions in Symptoms.
Step | Action | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |||||||
2 |
Does the scan tool display indicate Released? | Go to Step 3 | Go to Step 6 | ||||||
3 | Depress the brake pedal approximately half-way. Does the scan tool display indicate Applied? | Go to Intermittent Conditions | Go to Step 4 | ||||||
4 | Disconnect the extended travel brake switch connector. Does the scan tool display indicate Applied? | Go to Step 14 | Go to Step 5 | ||||||
5 | Test for a short to voltage on the extended travel brake switch signal circuit. Refer to Testing for a Short to Voltage in Wiring Systems. Did you find and correct the condition? | Go to Step 17 | Go to Step 16 | ||||||
6 | With a scan tool, observe the TCC brake switch display. Does the scan tool display indicate Released? | Go to Step 7 | Go to Step 11 | ||||||
7 |
Did you find and correct the condition? | Go to Step 17 | Go to Step 8 | ||||||
8 |
Does the scan tool indicate Released? | Go to Step 9 | Go to Step 10 | ||||||
9 | Inspect for poor connections at the TCC/extended travel brake switch. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | Go to Step 17 | Go to Step 14 | ||||||
10 | Test for the following conditions:
Did you find and correct the condition? | Go to Step 17 | Go to Step 16 | ||||||
11 | Inspect the IGN 1 fuse for an open circuit. Is the fuse open? | Go to Step 12 | Go to Step 13 | ||||||
12 |
Did you find and correct the condition? | Go to Step 17 | Go to Intermittent Conditions | ||||||
13 | Test for an open in the ignition 1 voltage circuit to the TCC/extended travel brake switch assembly. Did you find and correct the condition? | Go to Step 17 | Go to Step 14 | ||||||
14 | Test for proper TCC/extended travel brake switch adjustment. Did the switch require adjustment? | Go to Step 17 | Go to Step 15 | ||||||
15 | Replace the TCC/extended travel brake switch. Did you complete the replacement? | Go to Step 17 | -- | ||||||
16 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | Go to Step 17 | -- | ||||||
17 |
Does the DTC run and pass? | Go to Step 18 | Go to Step 2 | ||||||
18 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | System OK | |||||||
