Circuit Description
The powertrain control module (PCM) creates the vehicle speed signal by pulsing the signal circuit to ground at a rate of 4K PPM. The instrument panel cluster (IPC) converts the 4K PPM signal to a speedometer position. The IPC also receives a class 2 message from the PCM indicating the vehicle speed. The IPC uses this class 2 message for diagnostic purposes.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B0540 Speedometer Circuit
Conditions for Running the DTC
| • | The IPC receives a class 2 message from the PCM indicating that the vehicle speed is greater than 10 km/h (6 mph). |
| • | The ignition voltage is between 9-18 volts. |
Conditions for Setting the DTC
| • | The IPC does not detect a 4K PPM signal on the vehicle speed signal circuit. |
| • | The condition above must be present for a minimum of 5 seconds. |
Action Taken When the DTC Sets
The IPC stores a DTC B0540 in memory.
Conditions for Clearing the DTC
| • | The history DTC clears after 100 malfunction free warm-up cycles. |
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The IPC receives the clear code command from the scan tool. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Instrument Cluster Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Does the voltage measure greater than the specified value? | 9 V | Go to Step 3 | Go to Step 4 |
3 | Test the vehicle speed signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 5 |
4 | Test the vehicle speed signal circuit for an open or for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 |
5 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 |
6 | Inspect for poor connection at the harness connector of the instrument panel cluster (IPC). Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 |
7 | Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 9 | -- |
8 | Replace the IPC. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 9 | -- |
9 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
