Poor Navigation Radio Voice Recognition Performance - keywords inoperative microphone nav navigation onstar performance radio recognition voice

This PI was superceded to update circuit description and to specify to test microphone audio circuits between radio and VCIM before any other repair is made. Please discard PIC4745B.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Some customers with Navigation Radio (U3R) on a 2008 Cadillac DTS may report poor or no operation of the navigation radio voice or speech recognition system when using the "push to talk" button on the steering wheel controls. The system may fail to detect the command or will confuse the command, thus responding as something other than what was requested by the user.

The customer may also report that the OnStar voice recognition when using the hands-free calling (White Phone Icon) button on the inside rear view mirror assembly works properly. This will indicate that the concern is isolated to an internal audio pass-thru function within the OnStar module and not the fault of the navigation radio, microphone or its inputs.

Dealers should test circuits 7043 (gray/black microphone audio output signal +), 7044 (pink/black microphone audio ouput signal -) and 813 (bare shield) between the radio and VCIM for opens, shorts, high resistance before any further repairs are done. Be sure to confirm terminal tension and crimp with appropriate terminal test tools.

If no issues are found on the specified audio circuits it has been found that significant voice or speech recognition improvements for the Navigation Radio can be achieved by installing a 220 ohm resistor in series of the audio output signal circuit (#7043 gray/black microphone audio output signal +) from the OnStar module (VCIM) to the Navigation Radio System. A pre-assembled pigtail, along with detailed instruction can be obtained by contacting GM Technical Assistance who will ship one as needed to those dealers that have a customer condition/concern as outlined above and for the vehicle/RPO application(s).

Note: Any addresses or Points of Interest (POI) stored prior to the modifications to the audio output circuit MUST be deleted and re-stored to insure improved overall performance.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.