DTC P0654. GMC Truck TopKick C-Series (Conventional) C4/C5 2004

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Conventional) C4/C5 🢒 DTC 🢒 DTC P0654

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.

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

Schematic Reference: Instrument Cluster Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems

Did you perform the Instrument Cluster Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

Install a scan tool.
Start the engine.
With the scan tool, observe the Engine Speed parameter in the PCM Engine Data 1 data list.

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

Turn the ignition OFF.
Disconnect the powertrain control module (PCM) connector C2 (L18, LLY and LB7) or C3 (LG4).
Turn the ignition ON, with the engine OFF.
Measure the voltage from the engine speed signal circuit of the PCM to a good ground.

Does the voltage measure greater than the specified value?

9.0 V

Go to Step 4

Go to Step 5

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

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

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

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

Important: Program the replacement PCM.

Replace the PCM. Refer to:

•	Engine Control Module Replacement in Engine Controls - 6.6L (LB7).

•	Engine Control Module Replacement in Engine Controls - 6.6L (LLY).

•	Engine Control Module Replacement/Restore Fuel Rate Data in Engine Controls - 7.8L.

•	Powertrain Control Module Replacement in Engine Controls - 8.1L.

Did you complete the replacement?

Go to Step 10

Important: Program the replacement IPC

Replace the IPC. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

Go to Step 10

Use the scan tool in order to clear the DTCs.
Operate vehicle within the Conditions for Running this DTC.

Does the DTC reset?

Go to Step 2

System OK