DTC P0654 Engine Speed Output Circuit. Buick Park Avenue 1998

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1998 🢒 Park Avenue 🢒 DTC 🢒 DTC P0654 Engine Speed Output Circuit

DTC P0654 Engine Speed Output Circuit 3.8L

Circuit Description

The PCM supplies the ground to energize the Instrument Cluster tachometer. When the ignition switch is first turned on the PCM grounds the tachometer circuit. The circuit will remain grounded until the PCM receives the first 18X reference pulse. Once the 18X reference pulse is received, the PCM controls the pulse frequency in relationship to engine RPM. The tachometer is controlled at a rate of two pulses per crankshaft revolution.

Conditions for Running the DTC

•	The engine is running.

•	System voltage is between 9 and 16 volts.

Conditions for Setting the DTC

The PCM detects and incorrect voltage on the tachometer control circuit.

Diagnostic Aids

Refer to Instrument Cluster in Electrical Diagnosis section 8A for additional diagnostic information.

Check for the following conditions:

•	Poor connection at the PCM or instrument cluster. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

•

Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the PCM, turn the ignition ON and observe voltmeter connected to the tachometer control circuit at the PCM harness connector while moving connectors and wiring harnesses related to the tachometer control circuit. A change in voltage will indicate the location of the fault.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

Normally, ignition feed voltage should be present on the output driver circuit with the PCM disconnected and the ignition turned ON.

Checks for a shorted component or a short to B+ on the output driver circuit. Either condition would result in a measured current of over 0.5 amps.

Checks for a faulty instrument cluster.

This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed. Refer to PCM Replacement and Programming Procedures in Powertrain Control Module (PCM) and Sensors.

DTC P0654 - Engine Speed Output Circuit

Step

Action

Value(s)

Yes

Was Instrument Cluster Diagnostic System Check performed?

Go to Step 2

Go to A Diagnostic System Check - Instrument Cluster.

Was the Powertrain On-Board Diagnostic System Check performed?

Go to Step 3

Go to Powertrain On Board Diagnostic (OBD) System Check

Turn OFF the ignition switch, disconnect the PCM.
Turn ON the ignition switch.
Using DMM (J 39200), measure voltage between the tachometer control circuit at the PCM harness connector and ground.

Is voltage near the specified value?

B+

Go to Step 4

Go to Step 7

Set up DMM to measure 10 amp range.
Measure current between the tachometer control circuit and ground.
Monitor the current reading on the DMM for at least 2 minutes.

Does the current reading remain less than the specified value?

0.5 Amp

Go to Step 12

Go to Step 5

Disconnect the instrument cluster (leave the PCM disconnected).
Using DMM, measure voltage between the tachometer control circuit and ground.

Is voltage at the specified value?

Go to Step 15

Go to Step 6

Locate and repair short to voltage in the tachometer control circuit. Refer to Wiring Repairs .

Is action complete?

Go to Step 17

Check the ignition feed fuse for the instrument cluster.

Is the fuse blown?

Go to Step 8

Go to Step 9

Locate and repair the following short condition:

•	Short to ground in ignition feed circuit.

•	Shorted component. Refer to Power and Grounding Component Views .

Replace fuse.

Is action complete?

Go to Step 17

Disconnect the instrument cluster.
Turn ON the ignition switch, measure voltage between the ignition feed circuit for the instrument cluster and ground.

Is voltage near the specified value?

B+

Go to Step 10

Go to Step 14

Check the tachometer control circuit for an open or a short to ground.
If a problem is found, repair the tachometer control circuit.

Was a problem found?

Go to Step 17

Go to Step 11

Check the tachometer control circuit and the ignition feed circuit for a poor connection at the instrument cluster and at the PCM.
If a problem is found, replace faulty terminal(s). Refer to Repairing Connector Terminals .

Was a problem found?

Go to Step 17

Go to Step 15

Check for poor connections at the PCM.
If a problem is found, repair as necessary. Refer to Testing for Electrical Intermittents .

Was a problem found?

Go to Step 17

Go to Step 16

Check the tachometer control circuit for a poor connection at the PCM.
If a problem is found, replace faulty terminal. Refer to Repairing Connector Terminals .

Was a problem found?

Go to Step 17

Go to Step 16

Locate and repair open in ignition feed circuit to the instrument cluster. Refer to Wiring Repairs .

Is action complete?

Go to Step 17

Replace the instrument cluster. Refer to Instrument Cluster Replacement .

Is action complete?

Go to Step 17

Important: Replacement PCM must be programmed.

Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.