The interior lamp rheostat is a potentiometer. The Instrument Panel Module (IPM) determines the control setting based on the voltage from the interior lamp rheostat. The IPM sends out a class 2 message to the dash integration (DIM) module. The intensity of the of the IP switch backlighting shall be adjustable when ever the park lamps are on. The intensity of the vacuum florescent displays shall only be adjustable when it is night and the park lamps are active.
The IPM is powered.
The interior lamp rheostat voltage is less than 0.09 V or greater than 4.75 V.
Set dimming level to 100% (full brightness for all displays).
The IPM does not detect a voltage that is less than or greater than the predetermined value during the diagnostic self test.
The numbers below refer to the step numbers on the diagnostic table.
Tests for the proper operation of the circuit in the high voltage range.
Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
Tests for a short to ground in the 5 volt reference circuit.
Step | Action | Value(s) | Yes | No |
---|---|---|---|---|
1 | Did you perform the Lighting Systems Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Does the scan tool indicate that the Interior Dim Pot data parameter is within the specified range? | 0.09-4.8 V | Go to Step 12 | Go to Step 3 |
Does the scan tool indicate that the Interior Dim Pot data parameter is greater than the specified value? | 4.8 V | Go to Step 4 | Go to Step 8 | |
Does the scan tool indicate that the Interior Dim Pot data parameter is less than the specified value? | 0.09 V | Go to Step 5 | Go to Step 9 | |
Does the scan tool indicate that the Interior Dim Pot data parameter is greater than the specified value? | 4.8 V | Go to Step 7 | Go to Step 6 | |
6 | Test the 5 volt reference circuit of the IP dimmer switch for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
7 | Test the 5 volt reference circuit of the IP dimmer switch for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 11 |
8 | Test the input circuit of the IP dimmer switch for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
9 | Test the input circuit of the IP dimmer switch for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 10 |
10 | Test the sensor return circuit of the IP dimmer switch for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
11 | Inspect for poor connections at the harness connector of the headlamp switch. 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 15 | Go to Step 12 |
12 | Inspect for poor connections at the harness connector of the IPM. 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 15 | Go to Step 14 |
13 | Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
14 | Replace the IPM. Refer to Instrument Panel Module Replacement in Body Control System. Did you complete the replacement? | -- | Go to Step 15 | -- |
15 |
Does the DTC reset? | -- | Go to Step 2 | System OK |