GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 CTS - RHD 🢒 Engine 🢒 Engine Controls - 2.6L and 3.2L 🢒 DTC P0504

Circuit Description

The engine control module (ECM) monitors the stop lamp switch signal circuit and the torque converter clutch (TCC) brake switch/cruise control release signal circuit every 100 ms. The ECM monitors the status of the stop lamp switch signal circuit and the TCC brake switch/cruise control signal circuit to see if they match when the brake pedal is pressed or released.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The status of the stop lamp switch input to the ECM, and the TCC brake switch/cruise control input to the ECM do not match for at least 2 seconds continuously, for 10 occurrences. Each time the signals match then do not match a counter increments. When the counter reaches 10 the DTC will set.

Action Taken When the DTC Sets

When DTC P0504 is set the following will occur:

    • The cruise control is disabled.
    • The ECM will function as if the brake pedal is not pressed.
    • 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.

Conditions for Clearing the DTC
    • The DTC will clear when the status of the stop lamp switch input to the ECM, and the TCC brake switch/cruise control input to the ECM match for at least 2 seconds continuously for both the pressed position and the released position.
    • 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
    • Inspect for proper adjustment of the TCC/cruise control release switch, if equipped with automatic Transmission. Refer to Torque Converter Clutch/Cruise Control Release Switch Adjustment in Automatic Transmission - 5L40-E.
    • Inspect for proper adjustment of the stop lamp switch. Refer to Stop Lamp Switch Adjustment .
    • Check for internments and poor connections. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics and Cruise Control Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Lighting Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

Important: The stop lamp switch and the TCC/cruise control release switch must be adjusted correctly for proper operation. Refer to Stop Lamp Switch Adjustment and Torque Converter Clutch/Cruise Control Release Switch Adjustment in Automatic Transmission - 5L40-E.

  1. With the scan tool, observe the Stoplamp Pedal Switch parameter and Cruise Release Brake Pedal Switch parameter.
  2. Press and release the brake pedal.

Does the Stoplamp Pedal Switch parameter and Cruise Release Brake Pedal Switch parameter display change closely with each other?

Go to Diagnostic Aids

Go to Step 3

3
  1. With the scan tool, observe the Cruise Release Brake Pedal Switch parameter.
  2. Press and release the brake pedal.

Does the Cruise Release Brake Pedal Switch parameter display change with the brake pedal position?

Go to Step 6

Go to Step 4

4

  1. Turn off the ignition.
  2. Disconnect the TCC/cruise control release switch.
  3. Turn on the ignition, with the engine off.

Does the Cruise Release Brake Pedal Switch parameter display released?

Go to Step 5

Go to Step 12

5
  1. Turn off the ignition.
  2. Connect a 10 amp fused jumper between the ignition 1 voltage circuit of the TCC/cruise control switch and the signal circuit of the TCC/cruise control switch.
  3. Turn on the ignition, with the engine off.

Does the Cruise Release Brake Pedal Switch parameter display applied?

Go to Step 15

Go to Step 8

6
  1. Turn off the ignition.
  2. Disconnect the stop lamp switch.
  3. Turn on the ignition, with the engine off.
  4. With the scan tool, observe the Stoplamp Pedal Switch parameter.

Does the Stoplamp Pedal Switch parameter display OFF?

Go to Step 7

Go to Step 10

7
  1. Turn off the ignition.
  2. Connect a 20 amp fused jumper between the battery positive voltage circuit of the stop lamp switch and the stop lamp switch signal circuit.
  3. Turn on the ignition, with the engine off.

Does the Stoplamp Pedal Switch parameter display ON?

Go to Step 16

Go to Step 11

8

Test the ignition 1 voltage circuit of the TCC/cruise control switch for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 9

9

Test for an open or short to ground in the signal circuit of the TCC/cruise control switch. Refer to Circuit Testing and Wiring Repairs n Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 14

10

Test the stop lamp switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 14

11

Test the battery positive voltage circuit of the stop lamp switch for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 13

12

Test the TCC/cruise control switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 17

13

Test the stop lamp switch signal circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 14

14

Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 17

15

Inspect for poor connections at the harness connector of the TCC/cruise control release switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 18

16

Inspect for poor connections at the harness connector of the stop lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 19

17

Important: Program the replacement ECM.

Replace the ECM. Refer to Engine Control Module Replacement in Engine Controls 2.6L and 3.2L.

Did you complete the replacement?

Go to Step 20

--

18

Replace the TCC/cruise control release switch. Refer to Torque Converter Clutch/Cruise Control Release Switch Replacement in Automatic Transmission 5L40-E.

Did you complete the replacement?

Go to Step 20

--

19

Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement .

Did you complete the replacement?

Go to Step 20

--

20
  1. Use the scan tool in order to clear the DTCs .
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK