AA: EEC-IV No Start (Distributor Ignition) AA: Introduction
--------------------------------------------------------------------------------
AA1 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 Ignition Systems, Section 8A . GO to AA2 .
AA2 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 AA3 . REFER to Starting/Engine Service Manual Group.
AA3 CHECK FOR VREF AT THROTTLE POSITION (TP) SENSOR
Key off.
Disconnect TP sensor.
Key on, engine off.
Measure voltage between VREF circuit and SIG RTN circuit at the TP sensor vehicle harness connector.
Is voltage between 4.0 and 6.0 volts?
Yes No
RECONNECT TP sensor. GO to AA4 . GO to Pinpoint Test Step C1 .
AA4 CHECK FOR SPARK AT PLUGS
Disconnect the spark plug wire to any accessible cylinder.
Connect spark tester between spark plug wire and engine ground.
Crank engine and check for spark.
Reconnect the spark plug wire to the spark plug.
Was spark present and consistent?
Yes No
GO to AA14 . For Probe:
GO to AA25 .
For 7.0L Truck:
GO to AA15 .
All others:
GO to AA5 .
AA5 CHECK FOR SPARK AT COIL
Remove high tension coil wire from distributor and install spark tester.
Check for spark while cranking.
Reconnect high tension coil wire to distributor.
Was spark present during crank?
Yes No
For Probe:
REFER to Section 8B.
All others:
REFER to Section 8A , for ICM, cap, rotor and wire diagnosis. GO to AA6 .
AA6 CHECK CONTINUITY OF IGN GND CIRCUIT
Key off.
Disconnect Powertrain Control Module (PCM) 60 pin connector. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box, leave PCM disconnected.
For Probe:
Disconnect ICM and Camshaft Position (CMP) sensor.
For 7.0L Truck:
Disconnect Governor Control Module (GCM) and Camshaft Position (CMP) sensor.
For Distributor Mounted ICM:
Disconnect ICM module connector.
For all others:
Disconnect Camshaft Position (CMP) sensor.
Measure resistance between Test Pin 16 at breakout box and ICM or CMP sensor vehicle harness connector IGN GND circuit.
Is resistance less than 5.0 ohms?
Yes No
GO to AA7 . SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.
AA7 ISOLATION OF PROBLEM TO SPOUT CIRCUIT
Reconnect ICM and CMP sensor, as applicable.
Breakout box installed.
Connect PCM to breakout box.
Timing switch to "DIST" position on breakout box.
Attempt to start vehicle.
Does the vehicle start?
Yes No
Timing switch to "Computed" position on breakout box. GO to AA12 . GO to AA8 .
AA8 CHECK SPOUT SIGNAL
Key on, engine off.
Breakout box installed, PCM connected.
Timing switch to "DIST" position on breakout box.
Crank engine.
Measure voltage between Test Pin 36 (SPOUT) at breakout box and battery negative post during crank.
Is voltage between 3.0 and 6.0 volts?
Yes No
EEC system OK. REMOVE breakout box. RECONNECT all components.
For Probe:
REFER to Section 8B.
All others:
REFER to Section 8A for DI system diagnosis. PLACE timing switch to "Computed" position and GO to AA9 .
AA9 CHECK SPOUT AND PIP CIRCUITS FOR SHORT TO POWER
Key off.
Breakout box installed.
Disconnect PCM.
For Probe:
Disconnect ICM and CMP sensor.
For Distributor Mounted ICM:
Disconnect ICM module connector.
For all others:
Disconnect CMP and ICM sensor.
For 7.0L Truck: also disconnect GCM.
Key on.
Measure voltage between Test Pin 36 (SPOUT) at breakout box and battery negative post.
Measure voltage between Test Pin 56 (PIP) at breakout box and battery negative post.
Is voltage greater than 10.5 volts?
Yes No
SERVICE short circuit to the START circuit or to the VPWR circuit in the harness. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. GO to AA10 .
AA10 CHECK SPOUT AND PIP CIRCUITS FOR SHORTS TO GROUND
Key off.
Breakout box installed.
Disconnect PCM.
For Probe:
Disconnect ICM and CMP sensor.
For Distributor Mounted ICM:
Disconnect ICM module connector.
For all others:
Disconnect ICM and CMP sensor.
For 7.0L Truck: also disconnect GCM.
Measure resistance between Test Pin 36 (SPOUT) and Test Pins 16, 20, 40, 46 and 60 (short to GROUND) and 56 (short to PIP) at breakout box.
Measure resistance between Test Pin 56 (PIP) and Test Pins 16, 20, 40, 46 and 60 (short to GROUND) at breakout box.
Is each resistance greater than 10,000 ohms?
Yes No
GO to AA11 . SERVICE short circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. If vehicle does not start, GO to AA11 .
AA11 ISOLATE SHORT(S) IN PCM TO POWER AND GROUND
Key off.
Breakout box installed.
Reconnect PCM to breakout box.
For Probe:
Disconnect ICM and CMP sensor.
For Distributor Mounted ICM:
Disconnect ICM module connector.
For all others:
Disconnect ICM and CMP sensor.
For 7.0L Truck: also disconnect GCM.
Measure resistance between Test Pin 36 (SPOUT) and Test Pins 37 and 57 (short to POWER) and Test Pins 40 and 60 (short to GROUND) at breakout box.
Measure resistance between Test Pin 56 (PIP) and Test Pins 37 and 57 (short to POWER) and Test Pins 40 and 60 (short to GROUND) at breakout box.
Is each resistance greater than 500 ohms?
Yes No
RECONNECT all components. GO to AA12 . REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.
AA12 CHECK PIP SIGNAL
Key off.
Breakout box installed, PCM connected.
Measure voltage between Test Pin 56 and Test Pin 40 or 60 at breakout box.
Crank engine, record reading.
Is voltage between 3.0 and 7.0 volts?
Yes No
REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. GO to AA13 .
AA13 CHECK CONTINUITY OF PIP CIRCUIT
Key off.
Breakout box installed.
Disconnect PCM.
For Probe:
Disconnect ICM and CMP sensor.
For Distributor Mounted ICM:
Disconnect ICM module connector.
For all others:
Disconnect ICM and CMP sensor.
For 7.0L Truck: also disconnect GCM.
Measure resistance between Test Pin 56 at breakout box and PIP circuit at the following vehicle harness connectors, as appropriate: ICM, CMP sensor and/or GCM.
Is resistance less than 5.0 ohms?
Yes No
REMOVE breakout box. RECONNECT all components.
For Probe:
REFER to Section 8B.
All others:
REFER to Section 8A for DI system diagnosis. SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.
AA14 SPOUT SIGNAL VERIFICATION
Key off.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box and connect PCM to breakout box.
Ensure timing switch is in "Computed" position on breakout box.
Measure voltage between Test Pin 36 (SPOUT) and Test Pins 40 and 60 at the breakout box during crank.
Is voltage between 3.0 and 6.0 volts?
Yes No
GO to AA21 . GO to AA9 .
AA15 ATTEMPT TO RESTART VEHICLE
Key off.
Disconnect Governor Control Module (GCM).
Attempt to start vehicle
Does vehicle start?
Yes No
REPLACE GCM. RERUN Quick Test. GO to AA16 .
AA16 CHECK CONTINUITY OF PIP CIRCUIT
Key off.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box, leave PCM disconnected.
GCM disconnected.
Measure resistance between Pin 17 at GCM and Test Pin 56 at breakout box.
Is resistance less than 5.0 ohms?
Yes No
GO to AA17 . SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.
AA17 CHECK CONTINUITY OF PIP CIRCUIT
Key off.
PCM disconnected.
GCM disconnected.
Disconnect Camshaft Position (CMP) sensor.
Measure resistance between PIP circuit at the CMP sensor connector and Test Pin 56 at breakout box.
Is resistance less than 5.0 ohms?
Yes No
GO to AA18 . SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.
AA18 CHECK PIP CIRCUIT FOR SHORT TO POWER AND GROUND
Key off.
Breakout box installed.
PCM disconnected.
GCM disconnected.
CMP sensor disconnected.
Measure resistance between Test Pin 56 and Test Pins 16, 20, 40, 46 and 60 (short to ground) and Test Pins 26, 37 and 57 (short to power).
Is each resistance greater than 10,000 ohms?
Yes No
GO to AA19 . SERVICE short circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.
AA19 ISOLATE SHORTS IN PCM
Key off.
Breakout box installed.
Reconnect PCM to breakout box.
Measure resistance between Test Pin 56 and Test Pins 16, 20, 40, 46 and 60 (short to ground) and Test Pins 26, 37 and 57 (short to power).
Is each resistance greater than 10,000 ohms?
Yes No
GO to AA20 . REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.
AA20 CHECK PIP SIGNAL
Key off.
Breakout box installed, PCM connected.
Reconnect CMP sensor and GCM.
Measure voltage between Test Pin 56 and Test Pin 16 at breakout box.
Is voltage between 3.0 and 7.0 volts?
Yes No
REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. GO to AA6 .
AA21 CHECK FUEL PRESSURE
WARNING: IF FUEL STARTS LEAKING, TURN KEY OFF IMMEDIATELY. NO SMOKING.
Connect fuel pressure gauge.
Note initial pressure reading.
Observe pressure gauge as you pressurize fuel system. (Turn key to RUN for one second, then turn key to OFF. Wait 10 seconds. Repeat five times.)
Does fuel pressure increase?
Yes No
GO to Pinpoint Test Step S1 . TURN key OFF. REFER to Group 03 in the Service Manual.
AA25 CHECK VPWR CIRCUIT VOLTAGE
Key off.
Disconnect Camshaft Position (CMP) sensor.
Key on, engine off.
Measure voltage between VPWR circuit at CMP sensor vehicle harness connector and battery negative post.
Is voltage greater than 10.5 volts?
Yes No
GO to AA5 . GO to AA26 .
AA26 CHECK VPWR CONTINUITY
Key off.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary
Install breakout box, leave PCM disconnected.
CMP sensor disconnected.
Measure resistance between VPWR circuit at CMP sensor vehicle harness connector and Test Pin 37 or 57 at the breakout box.
Is resistance less than 5.0 ohms?
Yes No
GO to Pinpoint Test Step B1 . SERVICE open circuit. REMOVE breakout box. Reconnect all components. RERUN Quick Test
