1996 PCED OBDI
SECTION 18: Diesel Diagnosis — 7.3L DI Engine

AF: Unable to Activate Self Test/SCP Communication Error/DTC Not Listed
  AF: Introduction  

 

AF1 VERIFY SELF TEST ACTIVATION METHOD USED

Was the correct procedure used?
YesNo
Correct procedure for activating self test was used. GO to AF2.REFER to Scan Tool Diagnostic Test Procedures section for correct operating procedures.
 

AF2 CHECK PCM OUTPUT

Does engine start?
YesNo
GO to AF3.GO to B1.
 

AF3 CHECK B+ AT DATA LINK CONNECTOR (DLC)

Is resistance less than 5 ohms?
YesNo
GO to AF4.SERVICE open in DLC B+ circuit. RERUN Quick Test.
 

AF4 CHECK DLC CHASSIS GROUND CONTINUITY

Is resistance less than 5.0 ohms?
YesNo
GO to AF5.SERVICE open in DLC chassis ground circuit. RERUN Quick Test.
 

AF5 CHECK DLC PWR GND CIRCUIT CONTINUITY

Is resistance less than 5.0 ohms?
YesNo
GO to AF6.SERVICE open in DLC PWR GND circuit. RECONNECT the PCM. REMOVE breakout box. RERUN Quick Test.
 

AF6 CHECK DLC BUS(-) CIRCUIT CONTINUITY

Is resistance less than 5.0 ohms?
YesNo
GO to AF7.SERVICE open in the DLC

BUS (-) circuit. RECONNECT the PCM. REMOVE breakout box. RERUN Quick Test.
 

AF7 CHECK BUS(-) CIRCUIT FOR SHORT TO GROUND

Is resistance greater than 10,000 ohms?
YesNo
GO to AF8.SERVICE short to ground in the BUS(-) circuit. RECONNECT the PCM. REMOVE breakout box. RERUN Quick Test.
 

AF8 CHECK BUS(-) CIRCUIT FOR SHORT TO POWER

Was the voltage greater than 1.0 volt?
YesNo
SERVICE short to power in the BUS(-) circuit. RECONNECT the PCM. REMOVE breakout box. RERUN Quick Test.GO to AF9.
 

AF9 CHECK DLC BUS(+) CIRCUIT CONTINUITY

Is resistance less than 5.0 ohms?
YesNo
GO to AF10.SERVICE open in DLC BUS(+) circuit. RECONNECT the PCM. REMOVE breakout box. RERUN Quick Test.
 

AF10 CHECK BUS(+) CIRCUIT FOR SHORT TO POWER

Was the voltage greater than 1.0 volt?
YesNo
SERVICE short to power in the BUS(+) circuit. RECONNECT the PCM. REMOVE breakout box. RERUN Quick Test.GO to AF11.
 

AF11 CHECK BUS (+) AND BUS (-) SHORTED TOGETHER

Is resistance greater than 10,000 ohms?
YesNo
REPLACE PCM. CLEAR DTCs and RETEST.REPAIR short between BUS + and BUS - circuits.