U2151

DTC U2151 Navigation ECU Communication Error:

DTC U2151 Navigation ECU Communication Error (Part 1 of 2):

DTC U2151 Navigation ECU Communication Error (Part 2 of 2):

CIRCUIT DESCRIPTION
While the Ignition Switch is in the ACC or RUN positions, the Navigation Display Module sends a State of Health (SOH) message to the Navigation Data Processor on the ND Data Bus every 30 seconds, or during System Inspection Mode, to ensure that the system is operating properly. The ND Data Bus communication signals are carried from pin 26 of the Navigation Data Processor connector C2 on circuit 1171 to pin 14 of the Navigation Display Module connector C2 and from pin 13 of the Navigation Data Processor connector C2 on circuit 1219 to pin 15 of the Navigation Display Module connector C2.

CONDITIONS FOR RUNNING THE DTC
Navigation Display Module is running through System Inspection Mode.

CONDITIONS FOR SETTING THE DTC
There is an open circuit between the Navigation Data Processor and the Navigation Display Module, and communication initialization fails after a regular number of retries.

ACTION TAKEN WHEN THE DTC SETS
^ No connection with Audio ECU appears on the display.
^ This failure will have no effect outside the Navigation System.

CONDITIONS FOR CLEARING THE MIL/DTC
^ A current DTC will clear when the Navigation Display Module does not detect the failure during the last execution of the System Inspection Mode.
^ A history DTC will clear using a scan tool.

DIAGNOSTIC AIDS
^ An intermittent may be caused by the following:
- Mis-routed harness
- Rubbed through wire insulation
- Broken wire inside the insulation
^ Cycle the Ignition Switch even after a successful inspection with a scan tool so initialization will occur.
^ DTC U2151 will not set if DTC B1328, DTC B1327, or DTC U2150 is current.

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
1. Determines if the malfunction is present.
2. Checks circuit 1171 for a short to B+ condition.
3. Checks circuit 1219 for a short to B+ condition.
5. Checks circuit 1171 for a short to ground condition.
7. Checks circuit 1219 for a short to ground condition.
9. Checks circuit 1171 for an open condition.
11. Determines if the malfunction is due to an internal fault in the Navigation Display Module or an open condition in circuit 1219.