Any trouble codes? Check engine light on?
PCM depends upon crankshaft position sensor for RPM signals. PCM uses signals to determine triggering of power transistors and fuel injectors. See DTC P0335 OR P1336: CRANKSHAFT POSITION (CKP) SENSOR in appropriate SELF-DIAGNOSTICS article. Camshaft Position (CMP) Sensor See DTC P0340: CAMSHAFT POSITION (CMP) SENSOR in appropriate SELF-DIAGNOSTICS article. IGNITION TIMING CONTROL SYSTEM Timing Advance System PCM controls ignition timing advance based upon sensor input signals that reflect ignition timing needs. If timing problems are experienced, inspect input signals listed below for proper operation. To check input signals, see ENGINE SENSORS & SWITCHES or PCM pin voltage charts in PIN VOLTAGE CHARTS article. Ã A/C Clutch Signal Ã Closed Throttle Position Switch Ã Crankshaft Position Sensor Ã Engine Coolant Temperature Ã Ignition (START) Signal Ã Mass Airflow Sensor Ã Park/Neutral Switch Ã Power Steering Pressure Switch Ã Throttle Position Sensor Ã Vehicle Speed Sensor.
Self testing no scan tool:
Turn ignition on. Verify MIL is properly illuminated. If MIL does not illuminate, repair MIL circuit. See appropriate diagram in WIRING DIAGRAMS article. Turn mode selector switch on PCM fully clockwise. MIL should turn off. Wait 2 seconds, and turn mode selector fully counterclockwise. System is now in Diagnostic Test Mode II. Retrieve Diagnostic Trouble Codes (DTCs) by observing MIL, and counting the number of flashes. Record all codes set and then go to appropriate test procedure. MIL DTC numbering is different than CONSULT or GST DTC numbering. See appropriate DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION table. MIL Code Display MIL Code is a 4 digit number indicated by 2 separate 2 digit numbers flashed by MIL. The 2 separate numbers are separated by a pause (.9 second). The first number will be long flashes (.6 second), and the second will be short flashes (.3 second). If there is more than one MIL DTC stored, there will be a 2.1 second pause between codes. For example, 3 long (.6 second) flashes, a pause (.9 second), then followed by 3 short (.3 second) flashes of MIL indicate a MIL Code 0303. If 2 different MIL Codes are stored, such as 0406 and 0608, this would be displayed by 4 long flashes, pause, 6 short flashes, long pause, 6 long flashes, pause, 8 short flashes of MIL. Diagnostic Test Mode I As a bulb check, light glows when ignition is turned on and engine is not running. When vehicle is started, MIL will turn off, indicating that no malfunctions are detected. If a malfunction is detected while the engine is running, the MIL glows or flashes and a corresponding DTC will be set in PCM memory. Diagnostic Test Mode II Turn ignition on, but leave engine off. Using a small screwdriver, turn diagnostic mode selector on PCM fully clockwise and MIL should turn off. Wait at least 2 seconds, and then turn diagnostic mode selector fully counterclockwise which will enter into Diagnostic Test Mode II. MIL will flash any DTC(s) present. If 2 or more DTCs are displayed, they may be DTC's or 1st trip DTCs. These can be identified by using CONSULT or GST. To erase stored diagnostic information, go to ERASING NOTE: CHECK ENGINE or SERVICE ENGINE SOON light is now referred to as Malfunction Indicator Light (MIL). NOTE: Test modes cannot be switched with engine running. When ignition is turned off, power to PCM will turn off after 5 seconds. PCM will then return to Diagnostic Test Mode I. Ensure test mode selector is in fully counterclockwise position when vehicle is in use. NOTE: Test modes cannot be switched with engine running. When ignition is turned off, power to PCM will turn off after 5 seconds. PCM will then return to Diagnostic Test Mode I. Ensure test mode selector is in fully counterclockwise position when vehicle is in use. STORED INFORMATION. Erasing Stored Information The following emission related information will be erased from PCM memory: DTCs stored, 1st trip DTCs, freeze frame data, 1st trip freeze frame data, System Readiness Test (SRT) codes and test values. To erase this information, switch from Diagnostic Test Mode II to Diagnostic Test Mode I. While PCM is in Diagnostic Test Mode II, turn mode selector on PCM fully clockwise, wait 2 seconds and turn mode selector fully counterclockwise. RETRIEVING CODES USING GENERIC SCAN TOOL (GST) Turn ignition off. Connect scan tool to DLC located under left side dash panel. See Fig. 1. Turn ignition on. Enter program desired on GST screen. Perform each diagnostic mode according to appropriate service procedure displayed on GST. For further information, see the appropriate operation manual supplied by generic scan tool manufacturer. GST Mode Descriptions Typical GST modes available are listed with a brief definition of there function. These Generic Scan Tool modes were specified in SAE J1979. NOTE: Test modes cannot be switched with engine running. When ignition is turned off, power to PCM will turn off after 5 seconds. PCM will then return to Diagnostic Test Mode I. Ensure test mode selector is in fully counterclockwise position when vehicle is in use.
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Saturday, September 4th, 2010 AT 1:27 PM