Circuit Description
The steering wheel controls are simple momentary contact switches that connect a series of resistors so that each switch selection corresponds to a fixed resistance value. The truck body computer (TBC) determines which switch has been pressed by the voltage drop across the corresponding resistance value.
Conditions for Running the DTC
This test is run every 125 milliseconds.
Conditions for Setting the DTC
The switch must be stuck pressed for at least 30 seconds.
Action Taken When the DTC Sets
The TBC will ignore the switch command.
Conditions for Clearing the MIL/DTC
The stuck switch condition must be corrected.
Diagnostic Aids
| • | The following may cause an intermittent: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | When diagnosing for an intermittent short or an open, massage the wire harness while watching the test equipment for changes. |
Test Description
The number below refer to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Radio/Audio System Schematics | ||||
1 | Did you perform the Diagnostic System Check -- Entertainment System? | -- | Go to Step 2 | |
Does the Steering Wheel Controls parameter indicate the specified range? | 0-7 Counts | Go to Diagnostic Aids | Go to Step 3 | |
3 | Replace the steering wheel control switch. Refer to Steering Wheel Control Switch Assembly Replacement in Steering Wheel and Column. Did you complete the replacement? | -- | Go to Step 4 | -- |
4 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
