GM Service Manual Online
For 1990-2009 cars only

Refer to Engine Controls Schematic

Power, Ground, CMP, CKP 24X, CKP 7X, KS, and ICM


Object Number: 528131  Size: FS
Engine Controls Components
Information Sensors/Switches Description
HO2S 1 and HO2S 2
Engine Data Sensors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Power Distribution Schematics
Ground Distribution Schematics
.

Circuit Description

The powertrain control module (PCM) controls the pulse frequency in relationship to engine RPM, and sends the information Class II to the Instrument Cluster.

Diagnostic Aids

Refer to Diagnostic System Check - Instrument Cluster for additional diagnostic information.

Inspect for the following conditions:

Many situations may lead to an intermittent condition. Perform each inspection or test as directed.

Important: :  Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

    • Loose terminal connection
       -  Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
       -  Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
    • Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
    •  Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.

Step

Action

Values

Yes

No

1

Did you perform the Instrument Cluster System Check in Instrument Panel, Gauges and Console?

--

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

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

--

Go to Step 3

Go to Powertrain On Board Diagnostic (OBD) System Check

3

Are there any DTCs set?

--

Go to applicable DTCs

Go to Step 4

4

  1. Install a scan tool.
  2. Start the engine.
  3. Observe the engine RPM on the scan tool.

Does the scan tool RPM match the Instrument Cluster?

--

Go to Diagnostic Aids

Go to Step 5

5

  1. Verify proper operation of scan tool.
  2. Connect the scan tool to another vehicle and observe the RPM.

Does scan tool match vehicle RPM?

--

Go to Step 6

Go to Scan Tool Does Not Power Up Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

6

With the engine still running, observe 24X CKP sensor on the scan tool.

Does the scan tool indicate correct engine speed up to 1600 RPM?

--

Go to Tachometer Inaccurate in Instrument, Panel, Gauges, and Console

Go to Step 7

7

  1. Inspect for an open or short in the following circuits:
  2. • Class II Serial Data
    •  IC
    •  Bypass
    •  3X Reference High
    •  3X Reference Low
    • 24X CKP sensor circuits
  3. If a problem is found repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

Go to DTC P0336 Crankshaft Position (CKP) Sensor Performance