For 1990-2009 cars

### Circuit Description

The internal fault detection is handled inside the control module. No external circuits are involved.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1000 Electronic Control Unit (ECU) Performance

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description .

DTC Symptom | DTC Symptom Descriptor
--- | ---
00 | No Additional Information
31 | General Checksum Error
57 | Expected Reaction After Event Did Not Occur

### Conditions for Running the DTC

The module runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

### Conditions for Setting the DTC

The module has detected an internal malfunction.

### Action Taken When the DTC Sets

The module refuses all additional inputs.

### Conditions for Clearing the DTC

• | A current DTC clears when the malfunction is no longer present in all modules.

• | A history DTC clears in all of the modules except the sensing and diagnostic module (SDM), when the ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

• | If the code is set in the SDM it will never clear and the Air Bag indicator will remain illuminated.

### Diagnostic Aids

• | This DTC may be stored as a history DTC without affecting the operation of a module, except the SDM. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module. Attempt to clear the code from any module except if the code is set in the SDM.

• | If this DTC is retrieved as both a current and history DTC, replace the module.

• | If the code is set as current or history in the SDM, the SDM must be replaced.

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. Retrieve DTCs.

Is DTC retrieved as a current DTC?

Go to Step 3

Go to Diagnostic Aids

3 | Important: Perform the setup procedure for the module, if required. Replace the module. Refer to Control Module References . Did you complete the replacement? | Go to Step 4 | --
4 |

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