For 1990-2009 cars

### Circuit Description

Internal defects (hardware failure) in the cruise control module set DTC 55.

### Conditions for Setting the DTC

The following conditions can set a DTC 55:

• | EEPROM, RAM, ROM failure

• | The cruise control module detects a fault with the stepper motor.

• | DTC 55 can also set during the actuator test in which the stepper motor fails to respond when commanded.

### Action Taken When the DTC Sets

The cruise control is disabled.

### Conditions for Clearing the DTC

• | Using a scan tool.

• | Replacing the module.

### Diagnostic Aids

• | If a DTC 55 sets during an actuator test, inspect the cable for proper installation and routing before replacing the module.

• | Check the integrity of the power and ground circuits before replacing the cruise control module.

### Test Description

The numbers below refer to numbers on the diagnostic table.

1. This step verifies that DTC 55 is current.

2. A fault in the stepper motor can set a DTC 55. The control module will recognize the fault during the actuator test.

#### DTC 55 Cruise Control Module Malfunction

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Cruise Control System Check performed? | -- | Go to Step 2 | Go to Cruise Control System Check
2 |

1. Use the scan tool in order to clear the DTC.
2. Turn OFF the ignition.
3. Turn ON the ignition, with the engine OFF.
4. Access DTC information with the scan tool.

Is DTC 55 current?

--

Go to Step 3

Go to Step 4

3 | Before replacing the cruise control module inspect and test the following:

• | ignition feed circuit at terminal F

• | ground circuit at terminal E

Replace and perform the set up procedure for the cruise control module. Use the scan tool to perform the set up procedure.

Is the replacement complete?

--

Go to Cruise Control System Check

--

4 |

1. From the SPECIAL FUNCTIONS menu, select STEPPER MOTOR TEST.
2. Perform the test by following the instructions on the screen.

Does the scan tool display MOTOR TEST OK?

--

Go to Step 5

Go to Step 6

5 |

1. The conditions for setting a DTC 55 are not present at this time.
2. Prepare the vehicle for a road test.
3. Verify that the cruise control system operates OK.

Does the cruise control system operate OK?

--

System OK

Go to Step 7

6 | Did the test stop at any time during the procedure? | -- | Go to Step 7 | Go to Step 8
7 | Access DTC information with the scan tool. Is DTC 55 present? | -- | Go to Step 3 | Go to Step 8
8 |

1. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
2. If DTC 55 continues to set on a continuous intermittent basis, replace the cruise control module.

Did you find and correct the condition?

--

Go to Cruise Control System Check

--