Acura 3.5 RL Manual page 1321

Troubleshooting Precautions
General Operation
Refer to the Acura Navigation System Owner's Manual for the navigation system operating procedures.
Anti-theft Feature
The navigation system has a coded theft protection circuit. Be sure to get the customer's four-digit security code number
before;
• disconnecting the battery
• disconnecting the navigation unit connector
• removing the BACK-UP/RADIO (7.5 A) fuse from the under-hood fuse/relay box
After service, reconnect power to the navigation unit, and turn the ignition switch ON (II). Enter the 4-digit security code,
then select "Done". When replacing the navigation unit, be sure to give the customer the new anti-theft security code.
Symptom Diagnosis
Certain circumstances and system limitations will produce occasional vehicle positioning errors. Some customers may
think this indicates a problem with the navigation system when, in fact, the system is normal. Keep the following items in
mind when interviewing customers about navigation system symptoms.
Self-lnertial Navigation Limitations
The limitations of the self-inertial portion of the navigation system (the yaw rate sensor and the vehicle speed sensor) can
cause some discrepancies between the actual vehicle position and the indicated vehicle position. If there is a large dis-
crepancy, and the system is receiving GPS signals, the system will adjust the indicated vehicle position to the GPS vehicle
position. However, if GPS signals cannot be received, you must tune the vehicle position manually.
The following circumstances may cause vehicle positioning errors until the system can adjust to the GPS.
• Moving the vehicle with the engine stopped, such as by ferry or tow truck, or if the vehicle is spun on a turn table.
• Tire slippage, changes in tire rolling diameters, and some driving situations may cause discrepancies in travel dis-
tances. Examples of this include:
— Continuous tire slippage on a slippery surface.
— Driving with snow chains mounted.
— Abnormal tire pressures.
— Different diameter tires.
— Frequent lanes changes across a wide highway.
— Continuous driving on a straight or gently curving highway.
• Tolerances in the system and map accuracy sometimes limit how precisely the vehicle position is indicated.
Examples of this include:
— Driving on roads not shown on the map (map matching is not possible).
— Driving on a road that winds in one direction, such as a loop bridge, an interchange, or a spiral parking garage.
— Driving on a road with a series of sharp hair-pin turns.
— Driving on one of two close parallel roads.
— After making many 90 degree turns.