On Board Diagnostics II PCED

1999 PCED On Board Diagnostics II

SECTION 5: Pinpoint Tests

QA: Unable To Activate Self-Test/SCP Communication Error/DTC Not Listed

QA: Introduction

QA1 VERIFY SELF-TEST PROCEDURE

This pinpoint test addresses the following concerns:

Unable to access Continuous Memory DTCs.
Unable to activate KOEO Self-Test.
Unable to activate KOER Self-Test.
Scan tool communication concern.
DTC displayed by scan tool not listed.
Power Take Off (PTO), if equipped.
DTC P1001 KOER Self-Test cannot be completed.

Possible causes:

Damaged DLC.
Incorrect Self-Test procedure.
VREF is not in specification.
Idle rpm out of specification.
Open in DLC harness circuit.
Short in DLC harness circuit or associated modules.
Damaged PCM power relay circuit.
Damaged PCM.
PTO circuit, if equipped.

Disconnect scan tool from DLC. Inspect vehicle and scan tool DLC for damage. Repair as necessary.
PTO switch/actuator in OFF position.
Verify that the correct procedure was used to activate CONT, KOEO or KOER Self-Test for the scan tool (refer to Section 2 , Diagnostic Methods).

Was the correct Self-Test procedure used?

Yes	No
Correct procedure was used for activating Self-Test. GO to QA2 .	Correct procedure was not used for activating Self-Test. RETURN to Section 3 , Symptom Charts, Step 1: PCM Quick Test, and COMPLETE Self-Test using the correct procedure.

QA2 CHECK VREF VOLTAGE TO TP SENSOR

Disconnect throttle position sensor.
Key on, engine off.
Measure voltage between VREF and SIG RTN circuits at the TP sensor harness connector.

Is the voltage between 4.0 and 6.0 volts?

Yes	No
Voltage is in specification. RECONNECT the TP sensor. GO to QA3 .	Voltage is not in specification. RECONNECT the TP sensor. GO to Pinpoint Test Step C1 .

QA3 ABILITY TO ACCESS CONTINUOUS MEMORY DTCs

Can Continuous Memory DTCs be accessed?

Yes	No
GO to QA4 .	UNABLE to access Continuous Memory DTCs. KEY OFF. GO to QA7 .

QA4 ABILITY TO ACTIVATE KOEO SELF-TEST

Can KOEO Self-Test be activated?

Yes	No
GO to QA5 .	UNABLE to activate KOEO Self-Test. GO to QA6 .

QA5 ABILITY TO ACTIVATE KOER SELF-TEST

Can KOER Self-Test be completed?

Yes	No
If here for P1001 and other KOER DTCs are present, GO to Section 4 , DTC Charts and Description, for Pinpoint Test direction. Begin diagnosis with the first KOER DTC outputted. If the DTC is not listed in the (DTC) Charts, CHECK that the correct PCM is installed on the vehicle. Also CHECK for a Technical Service Bulletin (TSB) or OASIS broadcast message that indicates a PCM change or calibration (flash) update.	UNABLE to activate or complete KOER Self-Test. GO to QA6 .

Yes

If here for P1001 and other KOER DTCs are present, GO to Section 4 , DTC Charts and Description, for Pinpoint Test direction. Begin diagnosis with the first KOER DTC outputted. If the DTC is not listed in the (DTC) Charts, CHECK that the correct PCM is installed on the vehicle. Also CHECK for a Technical Service Bulletin (TSB) or OASIS broadcast message that indicates a PCM change or calibration (flash) update.

UNABLE to activate or complete KOER Self-Test. GO to QA6 .

QA6 RETRIEVE ANY CONTINUOUS MEMORY DTCs

NOTE 1: If failures are present in the following components or systems, this can prevent the Electronic EC strategy from completing Self-Test or cause the PCM to generate a scan tool communication error message: idle speed control; EGR system; fuel control system; electronic secondary air system; vehicle speed sensor circuits; mass air flow sensor circuits; transmission range sensor circuits.

NOTE 2: For information on retrieving MIL and non-MIL DTCs, refer to Section 2 , Quick Test, Continuous Memory Self-Test.

Key on, engine off.
Retrieve and record all Continuous Memory DTCs (MIL and non-MIL).
Key off.

Were any Continuous Memory DTCs present?

Yes	No
Continuous Memory DTCs are present. GO to Section 4 , DTC Charts and Description, for Pinpoint Test direction.	UNABLE to retrieve any Self-Test DTCs. GO to QA7 .

QA7 CHECK B+ VOLTAGE TO DATA LINK CONNECTOR (DLC)

Disconnect scan tool from DLC.
Inspect the DLC for damage. Repair as necessary.
Measure voltage between B+ circuit cavity at the DLC and ground.

Is voltage greater than 10.5 volts?

Yes	No
GO to QA8 .	REPAIR open in DLC B+ circuit.

QA8 CHECK DLC CHASSIS GROUND CIRCUIT FOR OPEN HARNESS

Measure resistance between chassis ground circuit at the DLC and chassis ground.

Is resistance less than 5.0 ohms?

Yes	No
GO to QA9 .	REPAIR open circuit.

QA9 CHECK DLC PWR GND CIRCUIT FOR OPEN IN HARNESS

Measure resistance between PWR GND circuit at the DLC and battery negative post.

Is resistance less than 5.0 ohms?

Yes	No
GO to QA10 .	REPAIR open circuit.

QA10 DATA LINK DIAGNOSTIC NETWORK TEST

Connect scan tool.
Key on, engine off.
Run Data Link Diagnostics.

Are any of the following messages displayed:

PCM: NO RESPONSE / NOT EQUIPPED

PCM: NO RESPONSE CKT914 (BUS-)

PCM: NO RESPONSE CKT915 (BUS+)

Yes	No
GO to QA11 .	Data Link passed. RERUN Quick Test.

QA11 NETWORK TEST RESULTS - CIRCUIT 914 AND CIRCUIT 915

Check the DATA LINK DIAGNOSTIC Network Test Results.

Are the following messages displayed:

CKT914=ALL MODULE NO RESP/NOT EQUIP or

CKT915=ALL MODULE NO RESP/NOT EQUIP?

Yes	No
Only CKT914=ALL MODULE NO RESP/NOT EQUIP, GO to QA12 . Only CKT915=ALL MODULE NO RESP/NOT EQUIP, GO to QA15 . Both CKT 914 and 915=ALL MODULE NO RESP/NOT EQUIP, REPAIR open to both BUS+/- or short circuit between BUS- and BUS+ and all associated modules.	CKT914=SOME MODULE NO RESP/NOT EQUIP, PCM: NO RESPONSE ON CKT914 (BUS+), GO to QA14 . CKT915=SOME MODULE NO RESP/NOT EQUIP, PCM: NO RESPONSE ON CKT915 (BUS-), GO to QA17 .

QA12 CHECK BUS+ FOR SHORT TO GROUND IN HARNESS

Key off.
Disconnect PCM.
Measure resistance of BUS+ circuit between PCM harness connector pin and chassis ground.

Is resistance greater than 50 ohms?

Yes	No
GO to QA13 .	REPAIR short circuit. Note: Short circuit can exist in harness or associated modules. REFER to Module Communication Network, Section 418-00 in Workshop Manual for further diagnosis.

QA13 CHECK BUS+ CIRCUIT FOR SHORT TO B+ IN HARNESS

Key on, engine off.
Measure voltage between BUS+ circuit at the PCM harness connector pin and chassis ground.

Is the voltage greater than 1.0 volt?

Yes	No
REPAIR short circuit. Note: Short circuit can exist in harness or associated modules. REFER to Module Communication Network, Section 418-00 in Workshop Manual for further diagnosis.	GO to QA14 .

QA14 CHECK DLC BUS+ CIRCUIT FOR OPEN IN HARNESS

Key off.
Disconnect PCM.
Measure resistance of BUS+ circuit between PCM harness connector pin and BUS+ circuit at the DLC.

Is resistance less than 5.0 ohms?

Yes	No
GO to QA18 .	REPAIR open circuit.

QA15 CHECK BUS- FOR SHORT TO GROUND IN HARNESS

Key off.
Disconnect PCM.
Measure resistance of BUS+ circuit between PCM harness connector pin and chassis ground.

Is resistance greater than 50 ohms?

Yes	No
GO to QA16 .	REPAIR short circuit. Note: Short circuit can exist in harness or associated modules. REFER to Module Communication Network, Section 418-00 in Workshop Manual for further diagnosis.

QA16 CHECK BUS- CIRCUIT FOR SHORT TO B+ IN HARNESS

Key on, engine off.
Measure voltage between BUS- circuit at the PCM harness connector pin and chassis ground.

Is the voltage greater than 6.0 volts?

Yes	No
REPAIR short circuit. Note: Short circuit can exist in harness or associated modules. REFER to Module Communication Network, Section 418-00 in Workshop Manual for further diagnosis.	GO to QA17 .

QA17 CHECK DLC BUS- CIRCUIT FOR OPEN IN HARNESS

Key off.
Disconnect PCM.
Measure resistance of BUS- circuit between PCM harness connector pin and BUS- circuit at the DLC.

Is resistance less than 5.0 ohms?

Yes	No
GO to QA18 .	REPAIR open circuit.

QA18 POWER TAKE OFF (PTO) APPLICATIONS

Is the vehicle equipped with a Power Take Off?

Yes	No
GO to QA19 .	Vehicle is not equipped with PTO. REPLACE PCM. (Refer to Section 2 , Flash EEPROM.)

QA19 CHECK PTO ON/OFF INPUT

Key on, engine off.
Measure the voltage between PCM harness connector Pin 4 and chassis ground while cycling the PTO switch/actuator.

Does the voltage cycle greater than 1.0 volt with the PTO on, and less than 1.0 volt with the PTO off?

Yes	No
PTO circuit is OK. REPLACE PCM. (Refer to Section 2 , Flash EEPROM.)	PTO circuit is not OK. GO to Pinpoint Test Step FB1 for further diagnosis.