2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 215
瀚慖f the test lamp does not illuminate, test the enable circuit for an open/high resistance.
7. Test for less than 1 V between the display position signal circuit terminal 5 and ground.
瀚慽f greater than the specified range, test the position signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
8. Connect a DMM between the display control circuit terminal 4 and ground. Press and release the NAV button on the Radio/HVAC Control.
Verify the voltage changes each time the display button is pressed. The value should change between less than 1 V to greater than 4 V.
瀚慖f the value is always less than 1 V, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal,
replace the radio.
瀚慖f the value is always greater than 1 V, test the control circuit for a short to voltage. If the circuit tests normal replace the radio.
9. If all circuits test normal, replace the Radio/HVAC display actuator.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Radio, Video, Audio Disc Player, and Navigation Information Display Actuator Replacement (See: Accessories and Optional
Equipment/Radio, Stereo, and Compact Disc/Radio/Stereo/Service and Repair/Radio, Video, Audio Disc Player, and Navigation Information
Display Actuator Replacement)
* Control Module References (See: Testing and Inspection/Programming and Relearning)for radio replacement, setup, and programming
B138A
DTC B138A
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC B138A 03
- Control Module Voltage Reference Output Circuit Low Voltage
DTC B138A 07
- Control Module Voltage Reference Output Circuit High Voltage
Diagnostic Fault Information
