On Board Diagnostics II PCED

1999 PCED On Board Diagnostics II

SECTION 5: Pinpoint Tests

A: No Start

A1 CHECK PASSIVE ANTI-THEFT SYSTEM (SECURILOCK)

Note: This vehicle may have an anti-theft system, which may be activated, causing the no start condition. Verify by viewing anti-theft indicator light on instrument panel or a Diagnostic Trouble Code (DTC P1260) may be present.

Verify anti-theft system.

Is the system activated?

Yes	No
GO to Electrical Anti-Theft, Section 419-01 in the Workshop Manual for diagnosis and testing.	GO to A2 .

A2 ATTEMPT TO CRANK ENGINE

NOTE: Verify inertia fuel shutoff (IFS) switch is set (button pushed in). Refer to Owner Guide for location.

Does engine crank?

Yes	No
GO to A3 .	REFER to the Starting Systems, Section 303-06 in the Workshop Manual.

A3 IDENTIFY TYPE OF NO START

NOTE: The purpose of this Test Step is to identify intermittent No Starts in order to guide the technician to the proper repair procedure.

Does the vehicle start now?

Yes	No
Vehicle is an intermittent No Start. GO to Pinpoint Test Step Z50 and prepare to use the Distributor/Less Ignition System Tester (DIST).	Natural gas vehicles: KEY OFF. GO to Pinpoint Test Step HA47 . All others: KEY OFF. GO to A4 .

A4 CHECK VREF VOLTAGE TO THROTTLE POSITION (TP) SENSOR

Disconnect TP sensor.
Key on, engine off.
Measure voltage between VREF and SIG RTN circuit at the TP sensor harness connector. Refer to the schematic in Pinpoint Test DH .

Is voltage between 4.0 and 6.0 volts?

Yes	No
KEY OFF. RECONNECT TP sensor. GO to A5 .	KEY OFF. GO to Pinpoint Test Step C1 .

A5 CHECK FEPS CIRCUIT FOR SHORT TO POWER IN HARNESS

Key on, engine off.
Measure voltage between Pin 13 at the data link connector and battery negative post.
(Refer to the Electrical and Vacuum Troubleshooting Manual for connector location.)

Is voltage greater than 9.0 volts?

Yes	No
REPAIR short to power.	For coil-on-plug vehicles: KEY OFF. GO to A17 . All others: KEY OFF. GO to A6 .

A6 CHECK PIP IN THE PCM

Note: The scan tool must be connected to a reliable power source that is powered with the key in the START position (such as directly to the vehicle battery). Also verify that the vehicle battery is fully charged.

Access PIP PID.
While viewing the PIP PID, crank engine.

Is the PIP PID switching on and off?

Yes	No
KEY OFF. GO to Pinpoint Test Step JB1 to check ignition coils, plugs and wires. If OK: Natural gas vehicles: GO to A15 . If returning from another pinpoint test or all others: GO to A7 .	KEY OFF. GO to Pinpoint Test Step JD1 .

A7 CHECK FUEL PRESSURE

WARNING: BEFORE SERVICING OR REPLACING ANY COMPONENTS IN THE FUEL SYSTEM, REDUCE THE POSSIBILITY OF INJURY OR FIRE BY FOLLOWING DIRECTIONS IN PINPOINT TEST HC WARNING, CAUTION, AND HANDLING.

Release the fuel pressure.
Install fuel pressure tester.
Scan Tool connected.
Key on, engine off.
Enter Output Test Mode (refer to Section 2 ) and run the fuel pump to obtain maximum fuel pressure.

Is the fuel pressure at the specified pressure (use the fuel pressure chart in Pinpoint Test HC)?

Yes	No
GO to A8 .	KEY OFF. GO to Pinpoint Test Step HC1 .

A8 CHECK FUEL PRESSURE LEAKDOWN

Observe WARNING, CAUTION AND HANDLING in Pinpoint Test HC.
Fuel pressure tester installed.
Scan Tool connected.
Key on, engine off.
Access Output Test Mode and run fuel pump to obtain maximum fuel pressure.
Exit Output Test Mode.
Verify fuel pressure remains within 16 kPa (5 psi) of the maximum pressure for 1 minute after turning pump off.

Does fuel pressure remain within 16 kPa (5 psi)?

Yes	No
KEY OFF. GO to A9 .	KEY OFF. GO to Pinpoint Test Step HC1 .

A9 CHECK FUEL INJECTORS FOR VPWR

Note: Check at least two fuel injectors, one on each bank. A no start condition can exist only if greater than 50% of the fuel injectors are without VPWR.

Disconnect any two fuel injectors.
Key on.
Measure VPWR circuit voltage at fuel injector harness connector.

Is voltage greater than 10.5 volts?

Yes	No
KEY OFF. GO to A10 .	REPAIR VPWR circuit.

A10 CHECK FUEL INJECTORS' ABILITY TO DELIVER FUEL

Connect fuel pressure gauge to Schrader valve.
Locate and disconnect the inertia fuel shutoff (IFS) switch.
Cycle key several times.
Monitor pressure gauge while cranking the engine for at least five seconds.

Is there a pressure drop greater than 34 kPa (5 psi) while cranking the engine?

Yes	No
The electronic engine control system is not the cause of the no start. RETURN to Section 3 , Symptom Chart for further diagnosis.	REPLACE PCM (refer to Section 2 , Flash EEPROM).

A15 CHECK FUEL PRESSURE ON NATURAL GAS VEHICLES

Connect scan tool to DLC.
Access FRP PID (fuel pressure).
Record fuel pressure.
Connect fuel pressure gauge to Schrader valve.
Key on, engine off.
Record fuel pressure.

Is fuel pressure between 552 and 827 kPa (80 and 120 psi) on the Scan Tool and fuel pressure gauge?

Yes	No
KEY OFF. GO to A16 .	KEY OFF. GO to Fuel Systems Pinpoint Test Step HB1 .

A16 CHECK INJECTOR SIGNAL FROM NGV MODULE

Note: This test requires a standard 12 volt test lamp. A properly operating system will show a dim glow.

Connect test lamp between the injector signal circuit and VPWR circuit pin at the injector harness.
Crank engine.

Does test lamp have a dim glow while cranking?

Yes	No
REPLACE PCM (refer to Section 2 , Flash EEPROM). GO to A6 .	No light or continuously bright light. GO to Fuel System Pinpoint Test Step HA47 .

A17 CHECK PCM DRIVER TO COILS

Connect incandescent test lamp between B+ and each coil driver circuit at the harness connector.
Crank engine.

Does lamp blink consistently and brightly (one blink per engine revolution)?

Yes	No
KEY OFF. GO to A7 .	KEY OFF. GO to Pinpoint Test Step JD1 .