GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 DeVille 🢒 DTC 🢒 DTC P1554

Circuit Description

The powertrain control module (PCM) has the ability to inhibit cruise control operation if conditions exist that would make cruise operation undesirable. The following conditions may inhibit cruise control operation:

    • The engine speed is too high or too low.
    • The vehicle speed is too high or too low.
    • The traction control has been active for longer than 1 second.
    • The vehicle acceleration or deceleration rate is too high.

If any of these conditions are present, the PCM will remove the ground from the cruise inhibit circuit.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1554 Cruise Control Feedback Circuit

Conditions for Running the DTC

The PCM is commanding the cruise control module to inhibit cruise control operation.

Conditions for Setting the DTC

The PCM detects a cruise engaged signal from the cruise control module, while inhibiting cruise control operation.

Action Taken When the DTC Sets
    • The PCM will not illuminate the malfunction indicator lamp (MIL).
    • The PCM will store the conditions present when the DTC sets as Fail Records data only.

Conditions for Clearing the DTC
    • The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using the scan tools Clear DTC Information function.

Diagnostic Aids

If the conditions is intermittent, refer to Testing for Intermittent Conditions and Poor Connections Intermittent Conditions in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Tests the PCM's ability to correctly read the signal voltage.

    2.

  2. Tests for a short on the cruise engaged signal circuit.

    3.

  3. This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.

Step

Action

Yes

No

Schematic Reference: Cruise Control Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step  2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, monitor the DTC information for DTC P1585 in the powertrain control module (PCM).

Is DTC P1585 also set?

Go to DTC P1585

Go to Step 3

3

With a scan tool, observe the Cruise Control Active display.

Does the Cruise Control Active display indicate YES?

Go to Step 5

Go to Step 4

4
  1. Review and record the scan tool Fail Records Information.
  2. Operate the vehicle within the Fail Records conditions.
  3. Using the scan tool, monitor the Specific DTC Information for DTC P1554 until the test runs.

Does the scan tool indicate that DTC P1554 failed this ignition?

Go to Step 5

Go to Diagnostic Aids

5

  1. Turn OFF the ignition.
  2. Disconnect the cruise control module connector.
  3. Turn ON the ignition switch, with the engine OFF.
  4. Using the scan tool, observe the Cruise Control Active display.

Does the Cruise Control Active display indicate YES?

Go to Step 6

Go to Step 7

6
  1. Turn OFF the ignition.
  2. Disconnect the appropriate PCM connector.
  3. Test the cruise control engaged circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 8

7

Replace the cruise control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 9

--

8

Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 9

--

9
  1. Use the scan tool in order to clear the DTC(s).
  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