Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2001 Mercury Sable, 2001 Mercury Mountaineer, 2001 Mercury Grand Marquis, 2001 Mercury Cougar, and 2001 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

Enter this test only when all steps under QUICK TEST have been successfully completed and engine still does not start or if directed here from another test or chart. This test is only intended to diagnose:

Powertrain Control Module (PCM)
Spark (PCM-Controlled)

To prevent replacement of good components, be aware the following non-EEC related areas and components may be cause of problem:

Fuel Quality & Quantity
Ignition (General Condition)
Engine Mechanical Components
Starter & Battery Circuits

1) Check Passive Anti-Theft System (Securilock)

If vehicle does not have an anti-theft system, go to next step. If vehicle has an anti-theft system, it may be activated causing the no-start condition. Verify by observing anti-theft indicator light being illuminated on instrument panel, or a DTC P1260 may be present. If anti-theft system is not activated, go to next step. If anti-theft system is activated, see appropriate ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT for diagnosis and testing.

2) Attempt To Crank Engine

Ensure Inertia Fuel Shutoff (IFS) switch is closed (button pushed in). Attempt to start engine. If engine does not crank, check vehicle starting and charging systems. See appropriate STARTERS or GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. Repair as necessary and retest. If engine cranks, go to next step.

3) Check For Intermittent No Start

Attempt to start engine. If engine now starts, fault is unable to be duplicated at this time. Go to TEST Z, step 2) . If engine does not start, turn ignition switch to OFF position and for CNG vehicles go to TEST HA, step 47) , or for all others, go to next step.

4) Check VREF At TP Sensor

Turn ignition switch to OFF position. Disconnect TP sensor. Turn ignition switch to ON position. Using a DVOM, measure voltage between circuits VREF and SIG RTN at TP sensor harness connector. See Fig 1-Fig 4 . If voltage is 4-6 volts, turn ignition switch to OFF position, reconnect TP sensor connector and go to next step. If voltage is not 4-6 volts, turn ignition switch to OFF position and go to TEST C, step 1).

Fig 1: Identifying TP Sensor Circuits & Connector Terminals - Cougar 2.0L & Escort 2.0L (4V)
Courtesy of FORD MOTOR CO.

Fig 2: Identifying TP Sensor Circuits & Connector Terminals - Focus 2.0L (4V) & Ranger 2.3L
Courtesy of FORD MOTOR CO.

Fig 3: Identifying TP Sensor Circuits & Connector Terminals - LS
Courtesy of FORD MOTOR CO.

Fig 4: Identifying TP Sensor Circuits & Connector Terminals - Except Cougar 2.0L, Escort 2.0L (4V), Focus 2.0L (4V), LS & Ranger 2.3L
Courtesy of FORD MOTOR CO.

5) Check Flash EPROM (FEPS) Circuit For Short To Power

Using a DVOM, measure voltage between negative battery terminal and DLC terminal No. 13. See Fig 5. If voltage is more than 9 volts, repair FEPS circuit for a short to VPWR. If voltage is 9 volts or less on models with coil-on-plug, go to step 17). If voltage is 9 volts or less on all other models, go to next step.

Fig 5: Identifying Data Link Connector (DLC) Terminals
Courtesy of FORD MOTOR CO.

NOTE: Ensure scan tool is connected to a reliable power source, such as the vehicle battery.

6) Check RPM Parameter Identification
Turn ignition switch to OFF position. Using scan tool, access RPM PID from PID/DATA MONITOR & RECORD menu. Observe RPM PID on scan tool while cranking engine. If RPM PID does not indicate cranking speed, turn ignition switch to OFF position and go to TEST JD, step 1) . If RPM PID value indicates cranking speed, check secondary ignition components (ignition coils, spark plugs and wires). See TEST JB, step 1) . Repair as necessary. If secondary ignition on CNG vehicles is okay, go to step 9). If secondary ignition on all other vehicles is okay, go to next step.

7) Check Fuel Pressure

Turn ignition switch to OFF position. Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE procedure under FUEL SYSTEM in appropriate REMOVAL, OVERHAUL & INSTALLATION article. Install fuel pressure gauge. With scan tool connected, turn ignition switch to ON position (engine off). Using scan tool, access OUTPUT TEST MODE. See OUTPUT TEST MODE under ADDITIONAL SYSTEM FUNCTIONS. Command fuel pump ON. If fuel pressure is as specified, go to next step. See FUEL PRESSURE SPECIFICATIONS table. If fuel pressure is not as specified, turn ignition switch to OFF position and go to TEST HC, step 1) .

8) Check Fuel Pressure Leakdown

Leave fuel pressure gauge installed and ignition switch turned to ON position (engine off). Using scan tool, access OUTPUT TEST MODE. See OUTPUT TEST MODE under ADDITIONAL SYSTEM FUNCTIONS. Command fuel pump ON to obtain maximum fuel pressure. Exit OUTPUT TEST MODE and turn ignition switch to OFF position. If fuel pressure remains within 5 psi (34 kPa) of maximum pressure for one minute after turning ignition switch to OFF position, go to next step. If fuel pressure does not remain within 5 psi (34 kPa), go to TEST HC, step 1) .

NOTE: A no-start condition can only occur if more than 50 percent of fuel injectors are without power.

9) Check VPWR Circuit At Fuel Injectors
Disconnect at least 2 fuel injector connectors. Turn ignition switch to ON position. Using a DVOM, measure voltage of VPWR circuit at disconnected fuel injector connectors. If any voltage measurement is 10.5 volts or less, repair VPWR circuit. If voltage measurements are more than 10.5 volts on CNG vehicles, go to step 15). If voltage measurements are more than 10.5 volts on all other vehicles, go to next step.

10) Check Fuel Injectors

Turn ignition switch to OFF position. Release fuel pressure. See appropriate FUEL SYSTEM PRESSURE RELEASE procedure under FUEL SYSTEM VENTING in REMOVAL, OVERHAUL & INSTALLATION article. Install fuel pressure gauge. Cycle ignition switch on and off several times. Disconnect Inertia Fuel Shutoff (IFS) connector. Monitor fuel pressure gauge while cranking engine for at least 5 seconds. If fuel pressure drops more than 5 psi (34 kPa) while cranking engine, EEC system is not cause of no-start. Diagnose by symptom. See SYMPTOMS in TROUBLE SHOOTING - NO CODES - EEC-V - CNG & GASOLINE article. If fuel pressure does not drop more than 5 psi (kPa), replace PCM.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 10) to step 15). No test procedures have been omitted.

15) Check Fuel Pressure (CNG Vehicles)

Turn ignition switch to OFF position. Release fuel pressure. See appropriate FUEL SYSTEM PRESSURE RELEASE procedure under FUEL SYSTEM VENTING in REMOVAL, OVERHAUL & INSTALLATION - CARS & TRUCKS - BI-FUEL & CNG article. Install fuel pressure gauge. With scan tool connected to DLC, access FRP PID (fuel pressure). Turn ignition switch to ON position (engine off). Record fuel pressure. If fuel pressure is 80-120 psi (552-827 kPa) on scan tool and pressure gauge, go to next step. If fuel pressure is not 80-120 psi (552-827 kPa) on scan tool and pressure gauge, go to TEST HB, step 1) .

16) Check Injector Signal From Natural Gas Vehicle Module

Turn ignition switch to OFF position. Connect a 12-volt test light between injector signal circuit and VPWR circuit terminal at fuel injector harness connector. Crank engine while observing test light. If test light glows dimly while cranking engine, replace PCM and go to step 6). If test light does not glow as specified, go to TEST HA, step 47) .

17) Check PCM Driver To Coils

Turn ignition switch to OFF position. Connect 12-volt test light between B+ and each coil driver circuit at harness connector. Crank engine while observing test light. Repeat procedure for each coil driver. Test light should blink brightly, once for each engine revolution. If test light blinks as specified, go to step 7). If test light does not blink as specified, go to TEST JD, step 1) .