Circuit Description
The powertrain control module (PCM) creates the engine speed signal by pulsing the signal circuit to ground at the rate of 2 pulses per engine revolution. The PCM monitors the voltage at the engine speed signal circuit. If the PCM determines that the voltage is not within the normal operating range, the PCM sets a DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0654 Engine Speed Output Circuit
Conditions for Running the DTC
| • | The engine speed is greater than 800 RPM. |
| • | The ignition voltage is greater than 9 volts but less than 18 volts. |
Conditions for Setting the DTC
| • | The PCM detects that the commanded state of the driver and the actual state of the signal circuit do not match. |
| • | The above condition is present for at least 5.0 seconds. |
Action Taken When the DTC Sets
| • | The PCM stores a DTC P0654 in memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time when the diagnostic test fails. The PCM stores this information in the Failure Records. |
Conditions for Clearing the DTC
| • | A history DTC clears after 40 malfunction free warm-up cycles. |
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The PCM 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 Engine Speed parameter match the tachometer display? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
3 |
Does the voltage measure greater than the specified value? | 9.0 V | Go to Step 4 | Go to Step 5 |
4 | Test the engine 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 10 | Go to Step 6 |
5 | Test the engine 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 10 | Go to Step 7 |
6 | 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 10 | Go to Step 8 |
7 | Inspect for poor connections 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 10 | Go to Step 9 |
8 | 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 10 | -- |
9 | 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 10 | -- |
10 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
