Your Vehicle: 2001 Ford Escort ZX2 L4-2.0L DOHC VIN 3
 
Vehicle » Powertrain Management » Computers and Control Systems » Testing and Inspection » Pinpoint Tests » QA: Unable To Activate Self-Test/SCP Communication Error/DTC Not Listed - Pinpoint Test  
 
 
  QA: Unable To Activate Self-Test/SCP Communication Error/DTC Not Listed - Pinpoint Test  
 

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

QA: Introduction See: QA: Unable To Activate Self-Test/SCP Communication Error/DTC Not Listed - 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 See: Diagnostic Trouble Code Tests and Associated Procedures\SECTION 2: Diagnostic Methods\Diagnostic Methods ).

Was the correct Self-Test procedure used?
Yes

  • Correct procedure was used for activating Self-Test. GO to QA2

.

No

  • 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. See: QT: Step 1: PCM Quick Test

QA2 CHECK VREF VOLTAGE TO TP SENSOR

  • Disconnect throttle position (TP) sensor.

Note: GO to Pinpoint Test DH See: DH: Throttle Position (TP) Sensor - Introduction and refer toPinpoint Test Schematics and Connectors for TP harness connector pin-out information.

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

Note: Loss of VREF caused by an open or short to power or ground can cause a SCP link communication error and/or unable to self-test.
Is the voltage between 4.0 and 6.0 volts?
Yes

  • Voltage is in specification.GO to QA3

.

No

.

QA3 CHECK LINK COMMUNICATION WITH TP SENSOR DISCONNECTED

  • TP sensor disconnected.
  • Scan tool connected.
  • Key on, engine off.
  • Attempt to access TP V PID.

Note: If TP V PID cannot be accessed. GO to QA4.

  • Reconnect TP sensor while monitoring PID.

Does scan tool communication error occur only when TP sensor is reconnected?
Yes

  • VREF shorted to SIG RTN in the sensor. REPLACE TP sensor.

No

  • GO to QA4

.

QA4 ABILITY TO ACCESS CONTINUOUS MEMORY DTCs

Can Continuous Memory DTCs be accessed?
Yes

  • GO to QA5

.

No

  • UNABLE to access Continuous Memory DTCs. KEY OFF. GO to QA8

.

QA5 ABILITY TO ACTIVATE KOEO SELF-TEST

Can KOEO Self-Test be activated?
Yes

  • GO to QA6

.

No

  • UNABLE to activate KOEO Self-Test. GO to QA7

.

QA6 ABILITY TO ACTIVATE KOER SELF-TEST

Can KOER Self-Test be completed?
Yes

  • If here for P1001 and other KOER DTCs are present, GO to Section

4, Diagnostic Trouble Code (DTC) Charts See: A L L Diagnostic Trouble Codes ( DTC )\Testing and Inspection\Diagnostic Trouble Code Descriptions
and Diagnostic Trouble Code (DTC) Descriptions See: A L L Diagnostic Trouble Codes ( DTC )\Testing and Inspection\Diagnostic Trouble Code Descriptions,
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 in the vehicle. Also CHECK for a Technical Service Bulletin (TSB)
or OASIS message that indicates a PCM change or calibration (flash) update.

No

  • UNABLE to activate or complete KOER Self-Test. GO to QA7

.

QA7 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 See: Scan Tool Testing and Procedures\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

and Diagnostic Trouble Code (DTC) Descriptions See: A L L Diagnostic Trouble Codes ( DTC )\Testing and Inspection\Diagnostic Trouble Code Descriptions
, for
Pinpoint Test direction.

No

  • UNABLE to retrieve any Self-Test DTCs. GO to QA8

.

QA8 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

  • GO to QA9

.

No

  • REPAIR open in DLC B+ circuit.

QA9 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

  • GO to QA10

.

No

  • REPAIR open circuit.

QA10 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

  • GO to QA11

.

No

  • REPAIR open circuit.

QA11 DATA LINK DIAGNOSTIC NETWORK TEST

  • Connect scan tool.
  • Key on, engine off.
  • Run Data Link Diagnostics.
  • NOTE: If scan tool does not have Data Link Diagnostic Network Test capability, GO to QA21.
  • Typical PCM network error messages:
  • PCM: NO RESPONSE/NOT EQUIPPED
  • PCM: NO RESPONSE CKT914 (BUS+)
  • PCM: NO RESPONSE CKT915 (BUS-)

Are any PCM network error messages displayed?
Yes

  • GO to QA12

.

No

  • Data Link passed. RERUN Quick Test.

QA12 NETWORK TEST RESULT - CIRCUIT 914 (BUS+) AND CIRCUIT 915 (BUS-)

  • Check the DATA LINK DIAGNOSTIC Network Test Results.
  • Typical ECU network error messages:
  • CKT914=ALL MODULE NO RESP/NOT EQUIP
  • CKT915=ALL MODULE NO RESP/NOT EQUIP

Are there any messages indicating "ALL ECU modules are not responding" displayed?
Yes

  • Only BUS(+) CKT914=ALL MODULE NO RESP/NOT EQUIP. GO to QA13

.
Only BUS(-) CKT915=ALL MODULE NO RESP/NOT EQUIP. GO to QA16

  1. Both BUS(+) CKT914 and BUS(-) 915=ALL MODULE NO RESP/NOT EQUIP. GO to QA21

.

No

  • CKT914=SOME MODULE NO RESP/NOT EQUIP, PCM: NO RESPONSE ON CKT914

(BUS+). GO to QA15

  1. CKT915=SOME MODULE NO RESP/NOT EQUIP, PCM: NO RESPONSE ON CKT915 (BUS-). GO to QA18

.

QA13 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

  • GO to QA14

.

No

  • REPAIR short circuit.

Note: Short circuit can exist in harness or associated modules. REFER to Information Bus.

QA14 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

  • REPAIR short circuit.

Note: Short circuit can exist in harness or associated modules. REFER to Information Bus.

No

  • GO to QA15

.

QA15 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

  • GO to QA19

.

No

  • REPAIR open circuit.

QA16 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

  • GO to QA17

.

No

  • REPAIR short circuit.

Note: Short circuit can exist in harness or associated modules. REFER to Information Bus.

QA17 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

  • REPAIR short circuit.

Note: Short circuit can exist in harness or associated modules. REFER to Information Bus.

No

  • GO to QA18

.

QA18 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

  • GO to QA19

.

No

  • REPAIR open circuit.

QA19 POWER TAKE OFF (PTO) APPLICATIONS

Is the vehicle equipped with a Power Take Off?
Yes

  • GO to QA20

.

No

  • Vehicle is not equipped with PTO. REPLACE PCM. (Refer to Section

2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM.)

QA20 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

for further diagnosis.

QA21 CHECK FOR BUS+ SHORT TO BUS-

  • Key off.
  • Disconnect PCM.
  • Measure resistance between BUS+ and BUS- circuits at the PCM harness connector.

Is resistance greater than 5.0 ohms?
Yes

  • GO to QA22

.

No

  • REPAIR short circuit.

Note: A short circuit can exist in the harness or associated SCP modules.

REFER to Information Bus.

QA22 CHECK FOR OPEN BUS+/- OPEN IN HARNESS

  • Measure resistance of BUS+ circuit between PCM harness connector pin and BUS+ circuit at the DLC.
  • Measure resistance of BUS- circuit between PCM harness connector pin and BUS- circuit at the DLC.

Are both resistances less than 5.0 ohms?
Yes

  • For scan tools with Data Link Diagnostic Network Test capability,GO to QA19

.

  • For scan tools without Data Link Diagnostic Network Test capability,

REFER to Information Bus. NOTE: If after completing diagnostic/repair information diagnosis and referred back to Computers and Control Systems Information. REPLACE PCM.

No

  • REPAIR open circuit.