For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC U2101: CAN Bus Maximum Configuration List

### Circuit/System Description

Some control modules must be programmed with software that specifically identifies the correct type and quantity of modules on the serial data bus based on RPO configuration. If a control module was not properly configured after installation, the appropriate U Code may be set for that module. No external circuit diagnosis is involved.

### Conditions for Running the DTC

• | Voltage supplied to the module is in the normal operating voltage range.

• | The vehicle power mode requires serial data communication to occur.

### Conditions for Setting the DTC

• | The control module is not configured properly.

• | Control unit recognises a programming error.

• | CAN-Bus configuration is invalid

### Conditions for Clearing the DTC

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

• | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

### Reference Information

#### Schematic Reference

Data Communication Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Data Link Communications Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool References

Control Module References for scan tool information

### Circuit/System Verification

1. Verify the appropriate DTC is not set.

⇒ | If the DTC is set along with other codes, diagnose all other codes first. If no other codes are set, program the control module specified by the DTC descriptor.

2. With a scan tool, clear the DTCs.
3. Ignition OFF, remove the scan tool, open and close the drivers door.
4. Wait 60 seconds, then verify the DTC is not set.

⇒ | If the DTC is set, replace the appropriate control module.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for control module replacement, setup, and programming