Powertrain Control Module Controlled Tachometer Diagnosis. Oldsmobile Intrigue 1999

For 1990-2009 cars only

Makes 🢒 Oldsmobile 🢒 1999 🢒 Intrigue 🢒 Engine 🢒 Engine Controls - 3.5L 🢒 Powertrain Control Module Controlled Tachometer Diagnosis

Cruise Control Module, Vehicle Speed Sensor (VSS)
Engine Controls Components
OBD II Symbol Description Notice
ESD Notice
ESD Notice

Circuit Description

The tachometer in the IPC receives engine RPM data via Class 2 serial data. If the tachometer is inoperative or malfunctioning, refer to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges, and Console. The Tach Output circuit provides a direct input of engine RPM to the EBTCM. The EBTCM pulls up the Tach Output circuit to 12 volts. The PCM pulse width modulates this circuit to ground. The EBTCM uses this engine RPM signal for ABS and Traction Control calculations. The PCM grounds the circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled.

Diagnostic Aids

Use the Connector Test Adapter Kit J 35616 for any test that requires probing the PCM harness connectors, electrical center fuse/relay cavities, component terminals or a component harness connector. Using this kit will prevent damage caused by improper probing of connector terminals.

If the problem is intermittent, refer to Intermittent Conditions for diagnosis.

Test Description

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

The actual frequency measured will vary with RPM. The presence of a frequency verifies that the PCM driver is functioning.

Typical values are approximately:

•	23 Hz at 700 RPM

•	46 Hz at 1400 RPM

•	69 Hz at 2100 RPM

Step

Action

Value(s)

Yes

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Turn the key to On leaving the engine off.
Using a scan tool select the Tachometer Circuit Status display.

Does the display indicate OK?

Go to Step 3

Go to Step 4

Start the engine.
Check the Tachometer Circuit Status display.

Does the display ever indicate Fault?.

Go to Step 4

Refer to Diagnostic Aids.

Turn the key to Off.
Disconnect the PCM.
Turn the key to On.
Using DMM J 39200 connected to ground, measure voltage on the Tach Output circuit at the PCM connector.

Is the voltage near the value specified?

12V

Go to Step 5

Go to Step 7

Turn the key to Off.
Disconnect the EBTCM.
Turn the key to On.
Using DMM J 39200 connected to ground, measure voltage on the Tach Output circuit.

Is voltage present on the Tach Output circuit with both controllers disconnected?

Go to Step 8

Go to Step 6

Turn the key to Off.
Reconnect the PCM.
Leave the EBTCM disconnected.
Connect DMM J 39200 between B+ and the Tach circuit in the EBTCM connector. Set the DMM to diode check, and Hz.
Start the engine.
Measure the frequency on the Tach Output circuit with the engine idling.

Is the frequency near the range specified?

15-30Hz

Go to Step 9

Go to Step 10

Turn the key to Off.
Disconnect the EBTCM.
Check the Tach Output circuit for the following conditions:

•	Open circuit

•	Short to Ground

•	Shorts to other circuits in the EBTCM or PCM harness connectors

Was a problem found and corrected?

System OK

Go to Step 9

Repair the Tach Output circuit shorted to voltage.

Is the action complete?

System OK

Check for poor connections/terminal tension at the EBTCM. Refer to Intermittents and Poor Connections Diagnosis .

Was a problem found and corrected?

System OK

Go to Diagnostic System Check - ABS in Antilock Brake System Delco VI or Diagnostic System Check - ABS in Antilock Brake System Bosch 5.3

Check for poor connections/terminal tension at the PCM. Refer to Intermittents and Poor Connections Diagnosis .

Was a problem found and corrected?

System OK

Go to Step 11

Replace the PCM. The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

System OK