Schematic
Refer to OnStar Schematics for three button assembly schematic information.
Circuit Description
If the voltage received from the three button assembly to the vehicle interface unit (VIU) is not between a predetermined high and low limit then the VIU will set the DTC.
Conditions for Running the DTC
| • | The ignition must be in the RUN or ACC position. |
| • | The VIU will test for the reference voltage from the three button assembly every 300 ms during VIU power on. |
and the VIU power must be on.
Conditions for Setting the DTC
| • | The signal voltage received by the VIU is greater than 2.8 volts. |
| • | The signal voltage received by the VIU is less than 3.2 volts. |
Action Taken When the DTC Sets
When the code is current the VIU will ignore all inputs from the OnStar® Button Assembly.
Conditions for Clearing the MIL/DTC
| • | The code can be cleared when the VIU does not detect a failure during the last diagnostic cycle. |
| • | The code will clear from history after 50 ignition cycles with no code present. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
-
This step inspects the circuits of the three button assembly for shorts, opens and continuity.
-
This step verifies the operation of the three button assembly through the Tech 2.
-
Using the Tech 2, verify the repair was complete.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the OnStar® Diagnostic System Check? | -- | Go to Step 2 | |
2 | Test the Keypad power circuit for and open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 3 |
3 | Test the Keypad ground circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 4 |
4 | Inspect for poor connections at the harness connector of the Rearview Mirror. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 5 |
5 | Measure the voltage from the Keypad power circuit to the Keypad ground circuit. Does the voltage measure near the specified value? | 3v | Go to Step 6 | Go to Step 7 |
6 | Replace the Rearview Mirror. Refer to Inside Rearview Mirror Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- |
7 | Inspect for poor connections at the harness connector of the VIU. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 |
8 | Replace the VIU. Refer to OnStar Vehicle Interface Unit Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- |
9 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
