Circuit Description
The TCC normally closed brake switch supplies a B+ signal on CKT 420 to the PCM. The circuit is opened when the brakes are applied. The stop lamp/cruise control normally open brake switch supplies a B+ signal on CKT 820 to the PCM when the brake is applied.
Conditions for Setting the DTC
| • | The switches disagree for 10 consecutive minutes. |
| or |
| • | The TCC and the cruise control brake switches are not toggling open and closed, during six brake applications on the same ignition cycle. |
Action Taken When the DTC Sets
| • | The PCM will not illuminate the Malfunction Indicator Lamp (MIL). |
| • | The PCM records the operating conditions at the time the diagnostic fails. This information stores in the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | A History DTC will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle. |
| • | Use of a Scan tool will clear the DTC codes. |
Diagnostic Aids
Refer to PCM Intermittent Diagnostic Trouble Codes or Performance. Check the driving habits of the customer and/or unusual traffic conditions (i.e. stop and go, expressway traffic).
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
-
This test simulates brake switch closed or the brakes as being OFF.
-
This test checks the feed circuit.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing any DTCs, use the Scan Tool Capture Info to save freeze frame and failure records for reference, as the Scan Tool loses data when using the Clear Info function. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | |
Does the Scan Tool display the Cruise Brake switch Closed and then Open when the brake is released? | -- | |||
Apply the brakes again. Does the Scan Tool display the Brake switch Open and then Closed when the brake is released? | -- | |||
4 |
Is the test light ON? | -- | ||
5 |
Does the Scan Tool display the Cruise Brake switch as Closed? | -- | ||
6 |
Is the test light ON? | -- | ||
7 |
Does the Scan Tool display the Cruise Brake switch as Closed? | -- | ||
8 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If any additional DTCs were stored, refer to the applicable DTC tables first. Are there any additional DTCs stored? | -- | Go to the applicable DTC table | Go to Diagnostic Aids |
9 | Check the normally open feed circuit (terminal B) for an open or a short to ground. Is the action complete? | -- | -- | |
10 | Check the normally open Cruise Brake switch signal circuit for an open or a short to ground. Was a repair performed? | -- | ||
11 | Check the normally open Cruise Brake switch signal circuit for a poor connection at the PCM. Was a repair performed? | -- | ||
12 | Check the normally closed feed circuit (terminal F) for an open or a short to ground. Is the action complete? | -- | -- | |
13 | Check the normally closed Brake switch signal circuit for an open or a short to ground. Was a repair performed? | -- | ||
14 | Check the normally closed Brake switch signal circuit for a poor connection at the PCM. Was a repair performed? | -- | ||
15 | Replace the stop lamp switch. Is the action complete? | -- | -- | |
16 |
Important: The new PCM must be programmed. Replace the PCM. Refer to PCM Replacement/Programming . Is the action complete? | -- | -- | |
17 |
Does the Scan Tool indicate the diagnostic Passed? | -- | ||
18 | Does the Scan Tool display any additional undiagnosed DTCs? | -- | Go to the applicable DTC table | System OK |
