For 1990-2009 cars

### Circuit Description

Modules connected to the GMLAN serial data circuit monitor for serial data communications on the GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. The steering colum control module (SCCM) maintains configuration list of all the modules on the buss. Modules also perform selff diagnostics to ensure their programming is functioning properly.

### DTC Descriptor

DTC U2101: Maximum Configuration List Not Programmed

### Conditions for Running the DTCs

• | 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

• | Control unit recognises programming error.

• | Control unit not programmed .

• | CAN-Bus Configuration 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.

### Circuit/System Verification

1. Verify DTC P0606 is not set as current.

⇒ | If DTC is set, replace the ignition coil.

2. With a scan tool, clear DTC's, and verify DTC P0606 is not set as current.

⇒ | If DTC is set, replace the ECM.

3. Verify DTC U2101 is not set as current.

⇒ | If DTC is set, replace the control module that set U2101.