U2098

DTC U2098

Diagnostic Instructions

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

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

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC U2098 00
- MOST Communication Enable Circuit Malfunction

DTC U2098 02
- MOST Communication Enable Circuit Short to Ground

Diagnostic Fault Information






Circuit/System Description

When the ignition is ON, the A11 Radio initializes the Media Oriented Systems Transport (MOST) bus by sending a short 100 ms low voltage pulse on the electronic control line (or MOST control line) connected to all devices contained on the MOST ring. When MOST receive, transmit, or control line faults are detected, transmit/receive messages will not received as expected from the wakeup request. The A11 Radio and the K74 Human Machine Interface Control Module will then perform diagnostics to isolate these MOST faults. If the MOST control line is shorted low to 0 V for excess amount of time, the A11 Radio will set a U2098 DTC and K74 Human Machine Interface Control Module will set a U0029 02 DTC. At this point the MOST bus will be unable to communicate until the shorted MOST control line is repaired.

Conditions for Running the DTC

* The system voltage is between 9-16 V.

* The ignition is ON.

* The Radio is ON.

Conditions for Setting the DTC

* The Radio senses a short to ground on the MOST control circuit.

* A current DTC is set when a MOST control circuit initialization is invoked and the circuit is detected to be pulled low (0 V) for longer than 1 second.

Action Taken When the DTC Sets

Many or all entertainment components may not function properly.

Conditions for Clearing the DTC

The DTC current status is cleared upon a successful MOST control circuit initialization occurs and the circuit is no longer pulled low.

Reference Information

Schematic Reference

* Data Communication Schematics [1][2]Electrical Diagrams

* Control Module References Control Module References

Connector End View Reference

Component Connector End Views Fuel Pump and Level Sensor Assembly

Description and Operation

Data Link Communications Description and Operation Description and Operation

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Testing

Note: Use the schematics to determine which MOST devices are on the A11 Radio's MOST control circuit 7 X2. Use the connector end views to identify the MOST control circuit terminal for each of those MOST devices.

1. Ignition OFF, disconnect the harness connectors at an easily accessible MOST device that shares the A11 Radio's MOST control circuit 7 X2. Ignition ON.

2. Verify that the DTC U2098 or DTC U0029 02 remains current.

• If the DTC becomes history
Replace the MOST device that was just disconnected.

• If the DTC remains current

3. With the prior devices disconnected, repeat steps 1 and 2 for each MOST device on the MOST control circuit except the A11 Radio.

4. Ignition OFF, disconnect the X2 harness connector at the A11 Radio.

5. Test for infinite resistance between the MOST control circuit terminal 7 X2 at the A11 Radio and ground.

• If less than infinite resistance
Repair the short to ground on the circuit.

• If infinite resistance

6. Replace the A11 Radio.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* GMLAN Wiring Repairs GMLAN Wiring Repairs

* Control Module References Control Module References for device replacement, programming and setup