Circuit Description
The instrument panel cluster (IPC) receives engine RPM information from the powertrain control module (PCM). Engine RPM input information is obtained from the PCM on a dedicated engine speed input to the IPC. The IPC also receives engine RPM data on the serial data line. The PCM is responsible for processing and sending engine RPM data to the IPC. The IPC will only display the engine RPM data that was sent by the PCM. The IPC monitors the engine RPM output information sent from the PCM for an out of range condition.
Conditions for Setting the DTC
| • | The IPC detects that the engine RPM is at least 7,400 RPM. |
| • | The above condition must be present for 1 second. |
Action Taken When the DTC Sets
| • | The IPC stores a DTC B0521. |
| • | The IPC displays engine RPM at 7,400 RPM. |
Conditions for Clearing the DTC
| • | The IPC detects that the engine RPM is less than 7,400 RPM. |
| • | A history DTC clears after 50 consecutive ignition cycles if the condition for the malfunction is no longer present. |
| • | The code is cleared using on-board diagnostics. |
| • | The IPC receives a clear code command from the scan tool. |
Diagnostic Aids
| • | The following conditions may cause an intermittent malfunction to occur: |
| - | The PCM is unable to process the correct RPM data. |
| - | Intermittent or erratic RPM signal sent from the PCM. |
| • | For intermittents and poor connections refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Instrument Cluster Schematics | ||||
1 | Did you perform the IPC Diagnostic System Check? | -- | Go to Step 2 | |
Does the tachometer operate properly? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
3 | Test the engine speed (tachometer) signal circuit for an open, short to voltage, or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 6 | Go to Step 4 |
4 | Inspect for poor connections at the harness connector of the IPC. 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 6 | Go to Step 5 |
5 | Replace the IPC. Refer to Instrument Cluster Replacement . Did you complete the replacement? | -- | Go to Step 6 | -- |
6 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
