Symptom Troubleshooting (Engine/fuel Control): Other Mazda Tribute I facelift

FOREWORD

Before proceeding with the following troubleshooting

1. Refer to «HOW TO USE THIS REPAIR INFORMATION»(ref-178489-S25233679992005061600000) to understand basic troubleshooting procedures.
2. Perform the diagnostic trouble code (DTC) inspection.
3. If a DTC is displayed, proceed with the appropriate inspection steps.

ENGINE OBD II MONITORS

The OBD II system monitors virtually all emission control systems and components that can affect tailpipe or evaporative emissions. In most cases, malfunctions must be detected before emissions exceed 1.5 times the applicable 50,000 or 100,000 mile emission standards. If a system or component exceeds emission thresholds or fails to operate within a manufacturer's specifications, a DTC will be stored and the MIL will be illuminated within two driving cycles.

The OBD II system monitors for malfunctions either continuously, regardless of driving mode, or non-continuously, once per drive cycle during specific drive modes. A DTC is stored in the PCM Keep Alive Memory (KAM) when a malfunction is initially detected. In most cases the MIL is illuminated after two consecutive drive cycles with the malfunction present. Once the MIL is illuminated, three consecutive drive cycles without a malfunction detected are required to extinguish the MIL. The DTC is erased after 40 engine warm-up cycles once the MIL is extinguished.

In addition to specifying and standardizing much of the diagnostics and MIL operation, OBD II requires the use of a standard Diagnostic Link Connector (DLC), standard communication links and messages, standardized DTCs and terminology. Examples of standard diagnostic information are freeze frame data and Inspection Maintenance (IM) Readiness Indicators.

Freeze frame data describes data stored in KAM at the point the malfunction is initially detected. Freeze frame data consists of parameters such as engine RPM and load, state of fuel control, spark, and warm-up status. Freeze frame data is stored at the time the first malfunction is detected, however, previously stored conditions will be replaced if a fuel or misfire fault is detected. This data is accessible with the WDS or equivalent to assist in repairing the vehicle.

OBD II Inspection Maintenance (IM) Readiness indicators show whether all of the OBD II monitors have been completed since KAM was last cleared. Mazda also stores a P1000 DTC to indicate that some monitors have not completed. In some states, it may be necessary to perform an OBD check in order to renew a vehicle registration. The IM Readiness indicators must show that all monitors have been completed prior to the OBD check.

COMPREHENSIVE COMPONENT MONITOR

The Comprehensive Component Monitor (CCM) monitors for malfunctions in any powertrain electronic component or circuit that provides input or output signals to the PCM that can affect emissions and is not monitored by another OBD II monitor. Inputs and outputs are, at a minimum, monitored for circuit continuity or proper range of values. Where feasible, inputs are also checked for rationality, outputs are also checked for proper functionality.

CCM covers many components and circuits and tests them in various ways depending on the hardware, function, and type of signal. For example, analog inputs such as throttle position or engine coolant temperature are typically checked for opens, shorts and out-of-range values. This type of monitoring is performed continuously. Some digital inputs like vehicle speed or crankshaft position rely on rationality checks - checking to see if the input value makes sense at the current engine operating conditions. These types of tests may require monitoring several components and can only be performed under appropriate test conditions.

Outputs such as the idle air control (IAC) solenoid are checked for opens and shorts by monitoring a feedback circuit or "smart driver" associated with the output. Other outputs, such as relays, require additional feedback circuits to monitor the secondary side of the relay. Some outputs are also monitored for proper function by observing the reaction of the control system to a given change in the output command. An IAC solenoid can be functionally tested by monitoring idle RPM relative to the target idle RPM. Some tests can only be performed under appropriate test conditions; for example, transmission shift solenoids can only be tested when the PCM commands a shift.

The following is an example of some of the input and output components monitored by the CCM. The components monitor may belong to the engine, ignition, transmissions, air conditioning, or any other PCM supported subsystem.

1. Inputs: Mass Air Flow (MAF) Sensor Intake Air Temperature (IAT) Sensor Engine Coolant Temperature (ECT) Sensor Or Cylinder Head Temperature (CHT) Sensor Throttle Position (TP) Sensor Camshaft Position (CMP) Sensor Fuel Tank Pressure (FTP) Sensor
2. Outputs: Fuel Pump (FP) Wide Open Throttle A/C Cutout (WAC) Idle Air Control (IAC) Shift Solenoid(s) (SS) Torque Converter Clutch (TCC) Solenoid EVAP Canister Purge Valve Canister Vent (CV) Solenoid
3. CCM is enabled after the engine starts and is running. A Diagnostic Trouble Code (DTC) is stored in Keep Alive Memory and the MIL is illuminated after two driving cycles when a malfunction is detected. Many of the CCM tests are also performed during the On Demand Self-Test.

EVAPORATIVE EMISSION (EVAP) VAPOR MANAGEMENT FLOW SYSTEM MONITOR

The EVAP vapor management flow system monitor is designed to verify that the evaporative emission (EVAP) canister purge valve is functioning properly and to verify the flow of fuel vapor from the EVAP canister purge valve to the engine. The electrical function of the EVAP canister purge valve is initially checked before the flow test can begin. Inputs from the ECT/CHT sensor, IAT sensor, MAF sensor and VSS/OSS are used to enable the flow test.

Note. The EVAP vapor management flow test will not run if an EVAP canister purge valve malfunction is indicated. The DTC associated with an electrical fault of the EVAP canister purge valve is P0443 (EVAP system control valve circuit malfunction).

Before the flow test is performed, the PCM will calculate how much fuel vapor is present while purging under engine operation. If the amount of fuel vapor calculated is above a calibrated threshold, the PCM assumes that there must be fuel vapor flow to the engine and that the EVAP canister purge valve is functioning properly. If this condition exists, the idle speed portion of the EVAP vapor management flow test will be bypassed and the test will pass and complete.

If the amount of fuel vapor calculated is below a calibrated threshold, the idle speed portion of the EVAP vapor management flow test must be executed to verify that the EVAP canister purge valve is functioning properly. An assumption of the flow test is that regardless of the fuel vapor in the EVAP canister, some portion of the fuel vapor flow will be air. The flow test will calculate the increase in the idle air required by the PCM when the duty cycle on the EVAP canister purge valve is reduced from 75% to 0%.

If the calculated increase in air flow exceeds a calibrated threshold, the PCM assumes the EVAP canister purge valve is functioning properly. If the calculated increase in air flow is negligible, the EVAP canister purge valve is not functioning properly. The DTC associated with this condition is P1443 (EVAP control system purge control valve malfunction).

The malfunction indicator lamp (MIL) is activated for DTCs P0443 and P1443 after two occurrences of the same fault.

EVAPORATIVE EMISSION (EVAP) RUNNING LOSS SYSTEM MONITOR

The evaporative emission (EVAP) running loss system monitor is an on-board strategy designed to detect a leak from a hole (opening) equal to or greater than 1.016 mm (0.040 inch) in the EVAP running loss system. The proper function of the individual components of the EVAP running loss system as well as its ability to flow fuel vapor to the engine is also examined. The EVAP running loss system monitor relies on the individual components of the EVAP running loss system to apply vacuum to the fuel tank and then seal the entire EVAP running loss system from atmosphere. The fuel tank pressure is then monitored to determine the total vacuum lost (bleed-up) for a calibrated period of time. Inputs from the engine coolant temperature (ECT) sensor or cylinder head temperature (CHT) sensor, intake air temperature (IAT) sensor, mass air flow (MAF) sensor, vehicle speed signal (VSS) or output shaft speed (OSS), fuel level input (FLI) and fuel tank pressure (FTP) sensor are required to enable the EVAP running loss system monitor.

Note. During the EVAP running loss system monitor repair verification drive cycle, a PCM reset will bypass the minimum soak time required to complete the monitor. The EVAP running loss system monitor will not run if the key is turned off after a PCM reset. The EVAP running loss system monitor will not run if a MAF sensor failure is indicated. The EVAP running loss system monitor will not initiate until the heated oxygen sensor (HO2S) monitor has completed.

The EVAP running loss system monitor is executed by the individual components of the EVAP running loss system as follows

1. The function of the EVAP canister purge valve is to create a vacuum on the fuel tank. A minimum duty cycle on the EVAP canister purge valve (75%) must be met before the EVAP running loss system monitor can begin.
2. The canister vent (CV) solenoid will close (100% duty cycle) with the EVAP canister purge valve at its minimum duty cycle to seal the EVAP running loss system from atmosphere and obtain a target vacuum on the fuel tank.
3. The fuel tank pressure (FTP) sensor will be used by the EVAP running loss system monitor to determine if the target vacuum on the fuel tank is being reached to perform the leak check. Once the target vacuum on the fuel tank is achieved, the change in fuel tank vacuum for a calibrated period of time will determine if a leak exists.
4. If the initial target vacuum cannot be reached, DTC P0455 (gross leak detected) will be set. The EVAP running loss system monitor will abort and not continue with the leak check portion of the test. If the initial target vacuum is exceeded, a system flow fault exists and DTC P1450 (unable to bleed-up fuel tank vacuum) is set. The EVAP running loss system monitor will abort and not continue with the leak check portion of the test. If the target vacuum is obtained on the fuel tank, the change in the fuel tank vacuum (bleed-up) will be calculated for a calibrated period of time. The calculated change in fuel tank vacuum will be compared to a calibrated threshold for a leak from a hole (opening) of 1.016 mm (0.040 inch) in the EVAP running loss system. If the calculated bleed-up is less than the calibrated threshold, the EVAP running loss system passes. If the calibrated bleed-up exceeds the calibrated threshold, the test will abort and rerun the test up to three times. If the bleed-up threshold is still being exceeded after three tests, a vapor generation check must be performed before DTC P0442 (small leak detected) will be set. This is accomplished by returning the EVAP running loss system to atmospheric pressure by closing the EVAP canister purge valve and opening the CV solenoid. Once the FTP sensor observes the fuel tank is at atmospheric pressure, the CV solenoid closes and seals the EVAP running loss system. The fuel tank pressure build-up for a calibrated period of time will be compared to a calibrated threshold for pressure build-up due to vapor generation. If the fuel tank pressure build-up exceeds the threshold, the leak test results are invalid due to vapor generation. The EVAP running loss system monitor will pass and complete. If the fuel tank pressure build-up does not exceed the threshold, the leak test results are valid and DTC P0442 will be set.
5. The malfunction indicator lamp (MIL) is activated for DTCs P0442, P0455 and P1450 (or P446) after two occurrences of the same fault. The MIL can also be activated for any EVAP running loss system component DTCs in the same manner. The EVAP running loss system component DTCs P0443, P0452, P0453 and P1451 are tested as part of the Comprehensive Component Monitor (CCM).

EXHAUST GAS RECIRCULATION (EGR) SYSTEM MONITOR - DIFFERENTIAL PRESSURE FEEDBACK EGR

The differential pressure feedback EGR system monitor is an on-board strategy designed to test the integrity and flow characteristics of the EGR system. The monitor is activated during EGR system operation and after certain base engine conditions are satisfied. Input from the ECT/CHT, IAT, TP and CKP sensors is required to activate the EGR system monitor. Once activated, the EGR system monitor will perform each of the tests described below during the engine modes and conditions indicated. Some of the EGR system monitor tests are also performed during On Demand Self-Test.

1. The differential pressure feedback EGR (DPFE) sensor and circuit are continuously tested for opens and shorts. The monitor looks for the DPFE circuit voltage to exceed the maximum or minimum allowable limits. The DTCs associated with this test are DTCs P1400 and P1401.
2. The EGR vacuum regulator solenoid is continuously tested for opens and shorts. The monitor looks for an EGR vacuum regulator circuit voltage that is inconsistent with the EGR vacuum regulator circuit commanded output state. The DTC associated with the test is DTC P1409.
3. The test for a stuck open EGR valve or EGR flow at idle is continuously performed whenever at idle (TP sensor indicating closed throttle). The monitor compares the DPFE circuit voltage at idle to the DPFE circuit voltage stored during key on engine off (KOEO) to determine if EGR flow is present at idle. The DTC associated with this test is DTC P0402.
4. The DPFE sensor upstream hose is tested once per drive cycle for disconnect and plugging. The test is performed with EGR valve closed and during a period of acceleration. The PCM will momentarily command the EGR valve closed. The monitor looks for the DPFE sensor voltage to be inconsistent for a no flow voltage. A voltage increase or decrease during acceleration while the EGR valve is closed may indicate a fault with the signal hose during this test. The DTC associated with this test is DTC P1405.
5. The EGR flow rate test is performed during a steady state when engine speed and load are moderate and EGR vacuum regulator duty cycle is high. The monitor compares the actual DPFE circuit voltage to a desired EGR flow voltage for that state to determine if EGR flow rate is acceptable or insufficient. This is a system test and may trigger a DTC for any fault causing the EGR system to fail. The DTC associated with this test is DTC P0401.
6. DTC P1408 is similar to P0401 but performed during KOER Self-Test conditions.
7. The MIL is activated after one of the above tests fails on two consecutive drive cycles.

FUEL SYSTEM MONITOR

The fuel system monitor is an on-board strategy designed to monitor the fuel trim system. The fuel control system uses fuel trim tables stored in the PCM's Keep Alive Random Access Memory (RAM) to compensate for variability in fuel system components due to normal wear and again. During closed-loop vehicle operation, the fuel trim strategy learns the corrections needed to correct a "biased" rich or lean fuel system. The correction is stored in the fuel trim tables. The fuel trim has two means of adapting; a Long Term Fuel Trim and a Short Term Fuel Trim. Long Term relies on the fuel trim tables and Short Term refers to the desired air/fuel ratio parameter "LAMBSE." Input from the ECT/CHT, IAT, and MAF sensors is required to activate the fuel trim system, which in turn activates the fuel system monitor. Once activated, the fuel system monitor looks for the fuel trim tables to reach the adaptive clip and LAMBSE to exceed a calibrated limit. The fuel system monitor will store the appropriate DTC when a fault is detected as described below.

1. The heated oxygen sensor (HO2S) detects the presence of oxygen in the exhaust and provides the PCM with feedback indicating air/fuel ratio.
2. A correction factor is added to the fuel injector pulsewidth calculation according to the long and short term fuel trims as needed to compensate for variations in the fuel system.
3. When deviation in the parameter LAMBSE increases, air/fuel control suffers and emissions increase. When LAMBSE exceeds a calibrated limit and the fuel trim table has clipped, the fuel system monitor sets a DTC as follows: The DTCs associated with the monitor detecting a lean shift in fuel system operation are DTCs P0171 and P0174. The DTCs associated with the monitor detecting a rich shift in fuel system operation are DTCs P0172 and P0175.
4. The MIL is activated after a fault is detected on two consecutive drive cycles.

HEATED OXYGEN SENSOR (HO2S) MONITOR

The HO2S monitor is an on-board strategy designed to monitor the HO2S sensors for a malfunction or deterioration which can affect emissions. The fuel control or upstream HO2S is checked for proper output voltage and response rate (the time it takes to switch from lean to rich and vice versa). Downstream HO2S used for catalyst monitor are also monitored for proper output voltage. The fuel system monitor and misfire detection monitor must also have completed successfully before the HO2S monitor is enabled.

1. The HO2S sensor senses the oxygen content in the exhaust flow and outputs a voltage between zero and 1.0 volt. Lean of stoichiometric (air/fuel ratio of approximately 14.7:1), the HO2S will generate a voltage between zero and 0.45 volts. Rich of stoichiometric, the HO2S will generate a voltage between 0.45 and 1.0 volt. The HO2S monitor evaluates both the upstream (fuel control) and downstream (catalyst monitor) HO2S for proper function.
2. Once the HO2S monitor is enabled, the upstream HO2S signal voltage amplitude and response frequency are checked. Excessive voltage is determined by comparing the HO2S signal voltage to a maximum calibratable threshold voltage. A fixed frequency closed loop fuel control routine is executed and the upstream HO2S voltage amplitude and output response frequency are observed. A sample of the upstream HO2S signal is evaluated to determine if the sensor is capable of switching or has a slow response rate. An HO2S heater circuit fault is determined by turning the heater on and off and looking for a corresponding change in the output state monitor (OSM) and by measuring the current going through the heater circuit. The HO2S monitor DTCs can be categorized as follows: The DTCs associated with HO2S lack the switching are DTCs P1130, P1131, P1132, P1150, P1151 and P1152. The DTCs associated with HO2S slow response rate are DTCs P0133 and P0153. The DTCS associated with HO2S signal circuit malfunction are DTCs P0131, P0136, P0151 and P0156. The DTCs associated with an HO2S heater circuit malfunction are DTCs P0135, P0141, P0155 and P0161. The DTC associated with the downstream HO2S not running in on-demand is DTC P1127. The DTCs associated with swapped HO2S connectors are DTCs P1128 and P1129.
3. The MIL is activated after a fault is detected on two consecutive drive cycles.

MISFIRE DETECTION MONITOR

The misfire detection monitor is an on-board strategy designed to monitor engine misfire and identify the specific cylinder in which the misfire has occurred. Misfire is defined as lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or any other cause. The misfire detection monitor will be enabled only when certain base engine conditions are first satisfied. Input from the ECT/CHT, MAF and CKP sensors is required to enable the monitor. The misfire detection monitor is also performed during on demand self-test.

1. The PCM synchronized ignition spark is based on information received from the CKP sensor. The CKP signal generated is also the main input used in determining cylinder misfire.
2. The input signal generated by the CKP sensor is derived by sensing the passage of teeth from the crankshaft position wheel mounted on the end of the crankshaft.
3. The input signal to the PCM is then used to calculate the time between CKP edges and also crankshaft rotational velocity and acceleration. By comparing the accelerations of each cylinder event, the power loss of each cylinder is determined. When the power loss of a particular cylinder is sufficiently less than a calibrated value and other criteria is met, then the suspect cylinder is determined to have misfired.
4. Misfire type A: Upon detection of a Misfire type A (200 revolutions) which would cause catalyst damage, the MIL will blink once per second during the actual misfire, and a DTC will be stored. Misfire type B: Upon detection of a Misfire type B (1000 revolutions) which will exceed the emissions threshold or cause a vehicle to fail an inspection and maintenance tailpipe emissions test, the MIL will illuminate and a DTC will be stored. The DTC associated with multiple cylinder misfire for a Type A or Type B misfire is DTC P0300. The DTCs associated with an individual cylinder misfire for a Type A or Type B misfire are DTCs P0301, P0302, P0303, P0304, P0305, and P0306.

MALFUNCTION INDICATOR LAMP (MIL)

The malfunction indicator lamp (MIL) alerts the driver that the PCM has detected an OBD II emission-related component or system fault. When this occurs, a DTC will be set.

1. The MIL is located on the instrument cluster and is labeled CHECK ENGINE.
2. Power is supplied to the MIL whenever the ignition switch is in the ON or START position.
3. The MIL will remain on in the ON/START mode as a bulb check during the instrument cluster proveout for approximately 4 seconds.
4. If the MIL remains on after the bulb check: The PCM illuminates the MIL for an emission-related concern and a DTC will be present. The instrument cluster will illuminate the MIL if the PCM does not send a control message to the instrument cluster. The PCM is operating in the Hardware Limited Operation Strategy (HLOS). The MIL circuit is shorted to ground.
5. If the MIL remains off (during the bulb check): Bulb is damaged. MIL circuit is open.
6. To turn off the MIL after a repair, a reset command from the WDS or equivalent must be sent, or three consecutive drive cycles must be completed without a fault.
7. If the MIL blinks at a steady rate, a severe misfire condition could possibly exist.
8. If the MIL blinks erratically, an intermittent open B+ to the bulb or an intermittent short to ground in the MIL circuit exist. Also, the PCM can reset while cranking if battery voltage is low.

MODIFICATIONS TO OBD II VEHICLES

Modifications or additions to the vehicle may cause incorrect operation of the OBD II system. Anti-theft systems, cellular telephones and CB radios must be carefully installed. Do not install these devices by tapping into or running wires close to powertrain control system wires or components .

Multiplexing

The increased number of modules on the vehicle dictates a more efficient method of communication. Multiplexing is the process of communicating several messages over the same signal path. This process allows multiple modules to communicate with each other through the signal path (BUS+/BUS-). Modules communicate with the powertrain control module using Standard Corporate Protocol (SCP) which determines the priority in which the signals are sent. (Refer to STANDARD CORPORATE PROTOCOL for more information.) Multiplexing reduces the weight of the vehicle by reducing electrical wiring.

Standard Corporate Protocol

The Standard Corporate Protocol (SCP) is a communication language used by Mazda for exchanging bi-directional messages (signals) between stand-alone modules and devices. Two or more signals can be sent over one circuit.

Included in these messages is diagnostic data that is output over the BUS+ and BUS- lines to the DLC. This information is accessible with the WDS or equivalent.

Flash Electrically Erasable Programmable Read Only Memory

The Flash Electrically Erasable Programmable Read Only Memory (FEEPROM) is an Integrated Circuit (IC) within the PCM. This IC contains the software code required by the PCM to control the powertrain. One feature of the FEEPROM is that it can be electrically erased and then reprogrammed without removing the PCM from the vehicle.

Idle Air Trim

Idle Air Trim is designed to adjust the Idle Air Control (IAC) calibration to correct for wear and aging of components. When engine conditions meet the learning requirement, the strategy monitors the engine and determines the values required for ideal idle calibration. The Idle Air Trim values are stored in a table for reference. This table is used by the PCM as a correction factor when controlling idle speed. The table is stored in Keep Alive Random Access Memory (RAM) and retains the learned values even after the engine is shut off. A DTC is output to indicate that the Idle Air Trim has reached its learning limits.

Whenever an IAC component is replaced or cleaned or a service affecting idle is performed, it is recommended that Keep Alive RAM be cleared. This is necessary so the idle strategy does not use the previously learned Idle Air trim values.

Once Keep Alive RAM has been reset, the engine must idle for 15 minutes (actual time varies between strategies) to learn new idle air trim values. Idle quality will improve as the strategy adapts. Adaptation occurs in four separate modes. The modes are shown in the following illustration.

Scheme 580

Fuel Trim

The fuel control system uses the fuel trim table to compensate for normal variability of the fuel system components caused by wear or aging. During closed loop vehicle operation, if the fuel system appears "biased" lean or rich, the fuel trim table will shift the fuel delivery calculations to remove the bias. The fuel system monitor has two means of adapting Short Term Fuel Trim (FT) and Long Term Fuel Trim (FT). Short Term FT is referred to as LAMBSE and Long Term FT references the fuel trim table.

Short Term Fuel Trim (Short Term FT) (displayed as SHRTFT 1 and SHRTFT2 on the WDS or equivalent) is a parameter that indicates short-term fuel adjustments. Short Term FT is commonly referred to as LAMBSE. LAMBSE is calculated by the PCM from HO2S inputs and helps maintain a 14.7:1 air/fuel ratio during closed loop operation. This range is displayed in percentage (%). A negative percentage means that the HO2S is indicating RICH and the PCM is attempting to lean the mixture. Ideally, Short Term FT may remain near 0% but can adjust between -25% to +35%.

Long Term Fuel Trim (Long Term FT) (displayed as LONGFT1 and LONGFT2 on the WDS or equivalent) is the other parameter that indicates long-term fuel adjustments. Long Term FT is also referred to as Fuel Trim. Long Term FT is calculated by the PCM using information from the Short Term FT to maintain a 14.7:1 air/fuel ratio during closed loop operation. The Fuel Trim strategy is expressed in percentages The range of authority for Long Term FT is from -35% to +35%. The ideal value is near 0% but variations of +20% are acceptable. Information gathered at different speed load points are stored in fuel trim cells in the fuel trim tables, which can be used in the fuel calculation.

Short Term FT and Long Term FT work together. If the HO2S indicates the engine is running rich, the PCM will correct the rich condition by moving Short Term FT in the negative range (less fuel to correct for a rich combustion). If after a certain amount of time Short Term FT is still compensating for a rich condition, the PCM "learns" this and moves Long Term FT into the negative range to compensate and allows Short Term FT to return to a value near 0%.

As the fuel control and air metering components age and vary from nominal values, the fuel trim learns corrections while in closed loop fuel control. The corrections are stored in a table that is a function of engine speed and load. The tables reside in Keep Alive Random Access Memory (RAM) and are used to correct fuel delivery during open and closed loop. As changing conditions continue the individual cells are allowed to update for that speed load point. If, during the adaptive process, both Short Term FT and Long Term FT reach their high or low limit and can no longer compensate, the MIL is illuminated and a DTC is stored.

Whenever a fuel injector or fuel pressure regulator is replaced, Keep Alive RAM should be cleared. This is necessary so the PCM does not use the previously learned fuel trim values.

Failure Mode Effects Management

Failure Mode Effects Management (FMEM) is an alternate system strategy in the PCM designed to maintain engine operation if one or more sensor inputs fail. When a sensor input is perceived to be out-of-limits by the PCM, an alternative strategy is initiated. The PCM substitutes a fixed value and continues to monitor the incorrect sensor input. If the suspect sensor operates within limits, the PCM returns to the normal engine operational strategy.

All FMEM sensors display a sequence error message on the WDS or equivalent. The message may or may not be followed by KOEO or Continuous Memory DTCs when attempting the KOER Self-Test.

Engine RPM/Vehicle Speed Limiter

The PCM will disable some or all of the fuel injectors whenever an engine RPM or vehicle overspeed condition is detected. The purpose of the engine RPM or vehicle speed limiter is to prevent damage to the powertrain. The vehicle will exhibit a rough running engine condition, and the PCM will store a Continuous Memory DTC P1270. Once the driver reduces the excessive speed, the engine will return to the normal operating mode. No repair is required. However, the technician should clear the PCM and inform the customer of the reason for the DTC.

Excessive wheel slippage may be caused by sand, gravel, rain, mud, snow, ice, etc. or excessive and sudden increase in RPM while in NEUTRAL or while driving.

Generic Electronic Module

For information on the generic electronic module, refer to GENERIC ELECTRONIC MODULE (GEM) PROGRAMMING - NGS .

Keep Alive Random Access Memory (RAM)

The PCM stores information in Keep Alive RAM (a memory integrated circuit chip) about vehicle operating conditions, and then uses this information to compensate for component variability. Keep Alive RAM remains powered when the ignition switch is off so that this information is not lost.

Integrated Electronic Ignition System

The Integrated Electronic Ignition (EI) System consists of a crankshaft position (CKP) sensor, coil pack(s), connecting wire, and PCM. The Coil On Plug (COP) Integrated EI System uses a separate coil for each spark plug and each coil is mounted directly onto the plug. The COP Integrated EI System eliminates the need for spark plug wires but does not require input from the camshaft position (CMP) sensor.

Vehicle Power

When the ignition switch is turned to the START or RUN position, battery positive voltage (B+) is applied to the coil of the Electronic EC power relay. Since the other end of the coil is wired to ground, this energizes the coil and closes the contacts of the Electronic EC power relay. Vehicle power (VPWR) is now sent to the PCM and the Electronic EC System as VPWR.

Vehicle REFERENCE Voltage

The vehicle reference voltage (VREF) is a positive voltage (about 5.0 volts) that is output by the PCM. This is a consistent voltage that is used by the 3-wire sensors.

Mass Air Flow Return

The mass air flow return (MAF RTN) is a dedicated analog signal return from the mass air flow (MAF) sensor. If serves as a ground offset for the analog voltage differential input by the MAF sensor to the PCM.

Signal Return

The signal return (SIG RTN) is a dedicated ground circuit used by most Electronic EC sensors and some other inputs.

Power Ground

Power ground (PWR GND) is an electric current path return for VPWR voltage circuit. The purpose of the PWR GND is to maintain sufficient voltage at the PCM.

Gold Plated Pins

Note. Damaged gold terminals should only be replaced with new gold terminals.

Some engine control hardware has gold plated pins on the connectors and mating harness connectors to improve electrical stability for low current draw circuits and to enhance corrosion resistance. The electronic EC components equipped with gold terminals will vary by vehicle application.

Mechanical Returnless Fuel System

The fuel system consists of a fuel tank with reservoir, fuel pump, fuel pressure regulator, fuel filter, fuel supply line, fuel rail, fuel rail pulse damper, fuel injectors, and Schrader/pressure test point. Operation of the system is as follows

1. The fuel delivery system is enabled during crank or running mode once the PCM receives a crankshaft position (CKP) sensor signal.
2. The fuel pump logic is defined in the fuel system control strategy and is executed by the PCM.
3. The PCM grounds the fuel pump relay, which provides VPWR to the fuel pump.
4. The inertia fuel shut-off (IFS) switch is used to de-energize the fuel delivery secondary circuit in the event of collision. The IFS switch is a safety device that should only be reset after a thorough inspection of the vehicle (following a collision).
5. For the 3.0L 4V, a pressure test valve (Schrader valve) is located on the fuel rail. This is used to measure fuel injector supply pressure for diagnostic procedures and repairs. For the 2.0L Zetec, a fuel pressure gauge must be installed in-line between the fuel supply line and the fuel rail. This is used to measure fuel injector supply pressure for diagnostic procedures and repairs. Refer to FUEL PRESSURE GAUGE SERVICE PROCEDURE - 2.0L ZETEC .
6. Located on the fuel rail is a pulse damper. The pulse damper reduces fuel system noise caused by the pulsing of the fuel injectors. The vacuum port located on the damper is connected to manifold vacuum to avoid fuel spillage in the event the pulse damper diaphragm were to rupture (the pulse damper should not be confused with a fuel pressure regulator).
7. The fuel injector is a solenoid-operated valve that meters the fuel flow to each combustion cylinder. The fuel injector is opened and closed a constant number of times per crankshaft revolution. The amount of fuel is controlled by the length of time the fuel injector is held open. The injector is normally closed and is operated by 12 volt VPWR from the power relay. The ground signal is controlled by the PCM.
8. There are three filtering or screening devices in the fuel delivery system. The intake sock is a fine, nylon mesh screen mounted on the intake side of the fuel pump. There is a fuel filler screen located at the fuel rail side of the fuel injector. The fuel filter assembly is located between the fuel pump and the pressure test point/Schrader valve.
9. The fuel pump (FP) module contains the fuel pump, fuel pressure regulator and the fuel sender assembly. The fuel pressure regulator is attached to the fuel pump in the fuel pump module located in the fuel tank. It regulates fuel pressure supplied to the fuel injectors. The fuel pressure regulator is a diaphragm-operated relief valve. Fuel pressure is established by a spring preload applied to the diaphragm. Excess fuel is bypassed through the regulator and returned to the fuel tank.

Differential Pressure Feedback EGR System

The Differential Pressure Feedback EGR (DPFEGR) system consists of a DPFEGR sensor, EGR vacuum regulator solenoid, EGR valve, orifice tube assembly, PCM and connecting wires and vacuum hoses. Operation of the system is as follows

1. The DPFEGR system receives signals from the engine coolant temperature (ECT) sensor, intake air temperature (IAT) sensor, throttle position (TP) sensor, mass air flow (MAF) sensor and crankshaft position (CKP) sensor to provide information on engine operating conditions to the PCM. The engine must be warm, stable and running at a moderate load and RPM before the EGR system is activated. The PCM deactivates EGR during idle, extended wide open throttle or whenever a failure is detected in an EGR component or EGR required input.
2. The PCM calculates the desired amount of EGR flow for a given engine condition. It then determines the desired pressure drop across the metering orifice required to achieve that flow and outputs the corresponding signal to the EGR vacuum regulator solenoid.
3. The EGR vacuum regulator solenoid receives a variable duty cycle signal (0 to 100%). The higher the duty cycle the more vacuum the solenoid diverts to the EGR valve.
4. The increase in vacuum acting on the EGR valve diaphragm overcomes the valve spring and begins to lift the EGR valve pintle off its seat, causing exhaust gas to flow into the intake manifold.
5. Exhaust gas flowing through the EGR valve must first pass through the EGR metering orifice. With one side of the orifice exposed to exhaust backpressure and the other to the intake manifold, a pressure drop is created across the orifice whenever there is EGR flow. When the EGR valve closes, there is no longer flow across the metering orifice and pressure on both sides of the orifice is the same. The PCM constantly targets a desired pressure drop across the metering orifice to achieve the desired EGR flow.
6. The DPFEGR sensor measures the actual pressure drop across the metering orifice and relays a proportional voltage signal (0 to 5 volts) to the PCM. The PCM uses this feedback signal to correct for any errors in achieving the desired EGR flow.

INTAKE AIR SYSTEMS

The Intake Air System provides clean air to the engine, optimizes air flow and reduces unwanted induction noise. The Intake Air System consists of an air cleaner assembly, resonator assemblies and hoses. The main component of the intake air system is the air cleaner assembly. The air cleaner assembly houses the air cleaner element that removes potential engine contaminants, particularly abrasive types. The mass air flow (MAF) sensor is attached internally or externally to the air cleaner assembly and measures the quantity of air delivered to the engine combustion chamber. The MAF sensor can be serviced or replaced as an individual component. The intake air system also contains a sensor that measures the intake air temperature which may also be integrated with the MAF sensor. Air induction resonators are part of the intake air housing (i.e., conical air cleaner). The function of an air induction resonator is to reduce induction noise. The air induction components are connected to each other and to the throttle body assembly with hoses.

COMMUNICATION ERROR

It is possible to receive a communication error from a WDS or equivalent when initiating a diagnostic test or accessing PIDs. The communication error can be caused by operator error, the vehicle wiring, connectors, the PCM or other control modules connected to the DLC wiring. The PCM will respond to a WDS or equivalent whenever the tool requests a test. These are not DTCs. Listed below are numeric codes and generic descriptions that a scan tool may display when trying to perform some PCM operations. It is possible to get other numeric codes not listed. For a complete list of communication response codes, refer to Society of Automotive Engineers (SAE) document J2190 enhanced E/E Diagnostic Test Modes. Some are normal responses to valid requests. The others are communication error responses. If the tool displays any of the communication error responses check scan tool connections, cable/adapters and entry of vehicle information.

Scheme 581

Visual Checks

1. Inspect the air cleaner and inlet ducting.
2. Check all engine vacuum hoses for damage, leaks, cracks, kinks and proper routing.
3. Check EEC system wiring harness for proper connections, bent or broken pins, corrosion, loose wires and proper routing.
4. Check the PCM, sensors and actuators for physical damage.
5. Check the engine coolant for proper level and mixture.
6. Check the transmission fluid level and quality.
7. Make all necessary repairs before continuing with the Quick Test.

Vehicle Preparation

1. Perform ALL safety steps required to start and run vehicle tests. Apply parking brake, place shift lever firmly into PARK position (NEUTRAL on manual transmission) and block drive wheels.
2. Turn off ALL electrical loads: radios, lamps, A/C, blower and fans.
3. Start engine and bring up to normal operating temperature before running Quick Test.

Accumulating PCM Data

PCM data can be accumulated in a number of ways. This includes circuit measurements with a multimeter or WDS or equivalent PID data. Acquisition of PCM PID data using the WDS or equivalent is one of the easiest ways to gather information. Gather as much data as possible when the fault is occurring to prevent improper diagnosis. Data should be accumulated during different operating conditions and based on the customer description of the intermittent fault. Compare this data with the known good data values.

This will require recording data in four conditions for comparison: 1) KOEO, 2) HOT IDLE, 3) 48 km/h (30 mph) and 4) 89 km/ h (55 mph).

Analyzing Data From Playback Of Stored PIDs

Look for abnormal events or values that are clearly incorrect. Inspect the signals for abrupt or unexpected changes. For example, during a steady cruise most of the sensor values should be relatively stable. Sensors such as TP, MAF and RPM that change abruptly when the vehicle is traveling at a constant speed are clues to a possible fault area.

Look for agreement in related signals. For example, if TP is changed during acceleration, a corresponding change should occur in IAC, RPM and SPARK ADV RD. Make sure the signals act in proper sequence. An increase in RPM after the TP is increased is expected. However, if RPM increases without a TP change, then a fault may exist.

Comparing PCM Data

After the PCM values have been acquired, it is necessary to determine the fault area. Typically, it will require the comparison of the actual values from the vehicle to the typical values.

The charts apply to different vehicle applications (i.e., model, engine, transmission, etc.).

System Pass

A system pass will be displayed when no DTCs are output and no NGS Tester communication error exists. System pass means that hardware monitored by the PCM is functioning within normal operating limits. When using the NGS Tester, all step by step instructions are defined in the NGS instruction manual. When using a generic scan tool, KOEO and KOER self-tests may not be supported. Refer to the manufacturer's manual for details.

Retrieving DTCs Procedure

Note. Start engine and bring up to operating temperature before running OBD Test.

Scheme 582

Scheme 583

Scheme 584

Scheme 585

Scheme 586

Scheme 587

Scheme 588

1. Perform the necessary vehicle preparation and visual inspection. Hook-up the NGS Tester to the vehicle.
2. Move the cursor to VEHICLE AND ENGINE SELECTION .
3. Move the cursor to SELECT NEW VEHICLE YEAR & MODEL . Press the trigger key to enter this selection.
4. Move the cursor to the proper year. Press the trigger key. If the model year is not displayed, use 2001.
5. Move the cursor to the appropriate model. Press the trigger key to enter this selection.
6. The vehicle selection screen showing the selected vehicle will be displayed. Move the cursor to the vehicle selected. Press the trigger key.
7. Move the cursor to DIAGNOSTIC DATA LINK in the main menu screen. Press the trigger key to enter into menu system diagnostics.
8. Move the cursor to PCM . Press the trigger.
9. Move the cursor to DIAGNOSTIC TEST MODES Press the trigger key to enter this selection.
10. Retrieve DTCs as follows: Continuous DTCs KOEO DTCs KOER DTCs

Playback Of Stored PIDs Procedure

Note. Look for abnormal behavior or values that are clearly incorrect. Inspect the signals for abrupt or unexpected changes. Look for agreement in related signals. Make sure signals act in proper sequence.

Scheme 589

Scheme 590

1. Select VIEW RECORDER AREAS .
2. Select a view area.
3. Select up to the four PIDs to review in the table format or two PIDs to review in the graph mode.
4. Table format: Scroll through the PID data while analyzing the information. Look for sudden drops or spikes in the values.
5. For example: Notice the major jump in the TP voltage while scrolling through the information.
6. Graph format: Scroll through the PID data while analyzing the information. Look for sudden drops or spikes in the linear lines showing the transformation of values to the line graph.

Scheme 591

1. Perform the "New Generation Star (NGS) Tester Hook-Up Procedure". See «ON-BOARD DIAGNOSTIC TEST - NEW GENERATION STAR (NGS) TESTER HOOK-UP PROCEDURE»(ref-178490-S22457564662005061600000) .
2. Perform step 1 through step 7 from the "Retrieving DTCs Procedure".
3. Turn key on.
4. Move the cursor to ACTIVE COMMAND MODES . Press the trigger key to enter this selection.
5. Move the cursor to OUTPUT TEST MODE . Press the trigger key to enter this selection.
6. Press MODE repeatedly to change the mode from ALL ON to LOW FAN, HIGH FAN, and ALL OFF . Return the mode to ALL ON .
7. Press START to run the fuel pump. Press STOP to turn off the fuel pump.
8. To open and close certain actuators in the emission system, press PIDS .
9. Press CLEAR to clear previous selected PIDs. NOTE: To select desired PIDs, place the shaded bar over the item(s) and press trigger. A star symbol appears next to the item when it's selected. Press START . The selected PID(s) and values appear. You can select 30 PIDs at a time.
10. Press START to turn on the fuel pump. Observe the values change from OFF to ON or from 0% to 100%. Press STOP to turn off the fuel pump.

A system pass will be displayed when no DTCs are output and no WDS or equivalent communication error exists. System pass means that hardware monitored by the PCM is functioning within normal operating limits. When using a generic scan tool, KOEO and KOER self-tests may not be supported. Refer to the manufacturer's manual for details.

DRIVE CYCLE RECOMMENDATIONS

1. Most OBDII monitors will complete more readily using a "steady foot" driving style during cruise or acceleration modes. Operating the throttle in a "smooth" fashion will minimize the time require for monitor completion.
2. Fuel tank level should be between 1/2 and 3/4 fill with 3/4 fill being the most desirable.
3. The Evaporative Monitor can only operate during the first 30 minutes of engine operation. When executing the procedure for this monitor, stay in part throttle mode and drive in a smooth fashion to minimize "fuel slosh".

1. Attach WDS or equivalent and access the ECT, FLI, and IAT PIDs. Verify the IAT PID is between 4-38°C (40-100°F). Verify the FLI PID is between 50% and 75%.
2. Warm the vehicle until the ECT PID reaches a minimum of 77°C (170°F).
3. Without returning to key OFF, clear all DTCs using WDS or equivalent generic OBD II function. DTC P1000 will remain.
4. Access the On-Board System Readiness Menu on the WDS or equivalent to view the status of the OBD II monitors.
5. Proceed with the selected monitor repair verification drive cycle. Once started, the engine must not be turned off.

OBD II DRIVE CYCLE

Note. Once started, the engine must not be turned off during the drive cycle.

1. Start the engine and drive the vehicle.
2. Drive in stop and go traffic for 20 minutes with at least 4 idle periods.
3. Drive on an expressway or highway for 10 to 15 minutes. Access and monitor the IAT PID on the scan tool during the entire highway drive. Heavy accelerations, sudden decelerations or wide open throttles are not recommended on any vehicle. NOTE: If inlet air temperature is below 40°F (4°C) at any time during the highway drive, the Evaporative Emission Monitor will not complete.
4. Access the ON BOARD SYSTEM READINESS menu to check completion status.
5. Rerun Continuous Memory Self-Test to check P1000 code status. NOTE: If the Evaporative Emission Monitor is the only monitor not showing completion status on the WDS or equivalent and P1000 has been cleared, the OBD II drive cycle has been completed.

Comprehensive Component Monitor Repair Verification Drive Cycle

1. Complete Vehicle Preparation.
2. For M/T, accelerate from 0 to 80 km/h (0 to 50 MPH). Continue to step 3. For A/T, from a stop and in overdrive, moderately accelerate to 80 km/h (50 MPH) and cruise for at least 15 seconds. Stop vehicle and repeat without overdrive to 64 km/h (40 MPH) cruising for at least 30 seconds. While at 64 km/h (40 MPH), activate overdrive and accelerate to 80 km/h (50 MPH) and cruise for at least 15 seconds. Stop for at least 20 seconds and repeat step 2 five times.
3. From a stop, accelerate to 104 km/h (65 MPH). Decelerate at closed throttle until 64 km/h (40 MPH) (no brakes). Repeat this 3 times.
4. Verify no DTCs are available with exception of P1000.

EGR Monitor Repair Verification Drive Cycle

1. Complete Vehicle Preparation.
2. From stop, accelerate to 72 km/h (45 MPH) at 1/2 to 3/4 throttle. Repeat 3 times. Verify no DTCs are available with exception of P1000.

HO2S Monitor Repair Verification Drive Cycle

1. Complete Vehicle Preparation.
2. Cruise at 64 km/h (40 MPH) for at least 5 minutes.
3. Verify no DTCs are available with exception of P1000.

Fuel Or Misfire Monitor Repair Verification Drive Cycle

1. Complete Vehicle Preparation.
2. Perform the following drive procedure three consecutive times. Accelerate on highway to 104 km/h (65 mph). Coast down with foot off the accelerator pedal (no brakes) from 104 km/h to 64 km/h (65 mph to 40 mph).
3. Verify no DTCs are available with exception of P1000.

EVAP Running Loss System Repair Verification Drive Cycle

Note. When the ambient air temperature outside is 4.4 to 37.8°C (40 to 100°F), or the altitude is above 2438 meters (8000 feet), the EVAP monitor will not run. FLI PID must be between 15 and 85%.

1. Complete Vehicle Preparation.
2. Cruise at 72 to 104 km/h (45 to 65 MPH) for 10 minutes (avoid sharp turns and hills).
3. To initiate the EVAP monitor, the EVAPPDC PID must increase to at least 75% (canister purge vent open). At this time, the EVAPCV PID will then display 100% (canister vent solenoid closed to seal the system) and the monitor will begin to run. Continue to drive at steady throttle with light steering until the EVAPCV displays 0% (canister vent solenoid open, system unsealed).
4. Bring the vehicle to a stop.
5. With the scan tool, view the EVAP monitor for completion through the On-Board System Readiness Tests Menu. Repeat Step 2 if the EVAP monitor is not complete.
6. Verify no DTCs are available with exception of P1000.

Catalyst Monitor Repair Verification Drive Cycle

1. Complete Vehicle Preparation.
2. Drive in stop and go traffic conditions. Include five different constant cruise speeds, ranging from 40 to 72 km/h (25 to 45 MPH) over a 10 minute period.
3. Verify no DTCs are available with exception of P1000.

Engine Oil Leaks

Note. Before installing new gaskets or oil seals, make sure that the fault is clearly established.

If the oil leak cannot be identified clearly by a visual inspection, carry out an UV test.

Fluorescent Oil Additive Method

1. Clean the engine with a suitable cleaning fluid to remove all traces of oil.
2. Drain the engine oil and refill with recommended oil, premixed with Gasoline Engine Oil Dye. Use a minimum 14.8 ml (0.5 ounce) to a maximum 29.6 ml (1 ounce) of fluorescent additive to all engines. If oil is not premixed, fluorescent additive must first be added to the crankcase.
3. Run engine for 15 minutes. Stop the engine and inspect all seal and gasket areas for leaks using a 12 Volt Master UV Diagnostic Inspection Kit. A clear bright yellow or orange area will identify leak. For extremely small leaks, several hours may be required for the leak to appear.
4. As necessary, pressurize the main oil gallery system to locate leaks due to incorrectly sealed, loose or cocked plugs. If the flywheel bolts leak oil, look for sealer on the threads.
5. Repair all leaks as necessary.

General Remarks

Note. Removing fuses and disconnecting electrical components causes the powertrain control module (PCM) to log an error message. After the measurements have been carried out this error message should be cleared from memory by connecting to PDU.

Note. Only check the compression pressure with the valves set to the prescribed clearance (if this can be adjusted).

The compression pressure should be checked with the engine at operating temperature.

Check The Compression Pressure

1. Remove the fuel pump relay.
2. Start the engine - the engine will start, run for a few seconds then stall.
3. Remove the spark plugs.
4. Install the compression tester.
5. Install an auxiliary starter switch in the starting circuit. With the ignition switch OFF, using the auxiliary starter switch, crank the engine a minimum of five compression strokes and record the highest reading. Note the approximate number of compression strokes required to obtain the highest reading.
6. Repeat the test on each cylinder, cranking the engine approximately the same number of compression strokes.
7. Install the components in reverse order, observing the specified tightening torques.
8. Reset the PCM fault memory.

Interpretation Of The Results

The indicated compression pressure are considered within specification if the lowest reading cylinder is within 75% of the highest reading.

If the measurement on one or more cylinders is much lower than the specified value, spray some engine oil into the combustion chamber and repeat the compression measurement.

If the reading greatly improves, the piston rings are damaged.

If the reading stays the same, the cause is either damaged valve seats or valve stem seals.

If the measurements for two cylinders next to each other are both too low then it is very likely that the cylinder head gasket between them is burnt through. This can also be recognized by traces of engine oil in the coolant and/or coolant in the engine oil.

EXCESSIVE ENGINE OIL CONSUMPTION

The amount of oil an engine uses will vary with the way the vehicle is driven in addition to normal engine-to-engine variation. This is especially true during the first 16,100 km (10,000 miles) when a new engine is being broken in or until certain internal components become conditioned. Vehicles used in heavy-duty operation may use more oil. The following are examples of heavy-duty operation

1. Trailer Towing Applications
2. Severe Loading Applications
3. Sustained High Speed Operation

Engines need oil to lubricate the following internal components

1. Cylinder Block Cylinder Walls
2. Pistons And Piston Rings
3. Intake And Exhaust Valve Stems
4. Intake And Exhaust Valve Guides
5. All Internal Engine Components

When the pistons move downward, a thin film of oil is left on the cylinder walls. As the vehicle is operated, some oil is also drawn into the combustion chambers past the intake and exhaust valve stem seals and burned.

The following is a partial list of conditions that can affect oil consumption rates

1. Engine Size
2. Operator Driving Habits
3. Ambient Temperatures
4. Quality And Viscosity Of Oil

Operation under varying conditions can frequently be misleading. A vehicle that has been run for several thousand miles on short trips or in below- freezing ambient temperatures may have consumed a "normal" amount of oil. However, when checking the engine oil level, it may measure up to the full mark on the oil level indicator due to dilution (condensation and fuel) in the engine crankcase. The vehicle then might be driven at high speeds on the highway where the condensation and fuel boil off. The next time the engine oil is checked it may appear that a liter of oil was used in about 160 km (100 miles). Per liter oil consumption rate is about 2,400 km (1,500 miles) per liter.

Make sure the selected engine oil meets Jaguar specification and the recommended API performance category "SG" and SAE viscosity grade as shown in the vehicle Owner Literature. It is also important that the engine oil is changed at the intervals specified for the typical operating conditions.

Interpreting Vacuum Gauge Readings

A careful study of the vacuum gauge reading while the engine is idling will help pinpoint trouble areas. Always conduct other appropriate tests before arriving at a final diagnostic decision. Vacuum gauge readings, although helpful, must be interpreted carefully.

Most vacuum gauges have a normal band indicated on the gauge face.

The following are potential gauge readings. Some are normal; others should be investigated further.

Scheme 592

1. NORMAL READING: Needle between 51-74 kPa (15-22 in-Hg) and holding steady.
2. NORMAL READING DURING RAPID ACCELERATION: When the engine is rapidly accelerated (dotted needle), the needle will drop to a low (not to zero) reading . When the throttle is suddenly released, the needle will snap back up to a higher than normal figure.
3. NORMAL FOR HIGH-LIFT CAMSHAFT WITH LARGE OVERLAP: The needle will register as low as 51 kPa (15 in-Hg) but will be relatively steady. Some oscillation is normal.
4. WORN RINGS OR DILUTED OIL: When the engine is accelerated (dotted needle), the needle drops to 0 kPa (0 in-Hg). Upon deceleration, the needle runs slightly above 74 kPa (22 in-Hg).
5. STICKING VALVES: When the needle (dotted) remains steady at a normal vacuum but occasionally flicks (sharp, fast movement) down and back about 13 kPa (4 in- Hg), one or more valves may be sticking.
6. BURNED OR BENT VALVES: A regular, evenly spaced, down scale flicking of the needle indicates one or more burned or damaged valves. Insufficient hydraulic valve tappet or hydraulic lash adjuster clearance will also cause this reaction.
7. POOR VALVE SEATING: A small but regular down scale flicking can mean one or more valves are not seating correctly.
8. WORN VALVE GUIDES: When the needle oscillates over about a 13 kPa (4 in-Hg) range at idle speed, the valve guides could be worn. As engine speed increases, the needle will become steady if guides are responsible.
9. WEAK VALVE SPRINGS: When the needle oscillation becomes more violent as engine RPM is increased, weak valve springs are indicated. The reading at idle could be relatively steady.
10. LATE VALVE TIMING: A steady but low reading could be caused by late valve timing.
11. IGNITION TIMING RETARDING: Retarded ignition timing will produce a steady but somewhat low reading.
12. INSUFFICIENT SPARK PLUG GAP: When spark plugs are gapped too close, a regular, small pulsation of the needle can occur.
13. INTAKE LEAK: A low, steady reading can be caused by an intake manifold or throttle body gasket leak.
14. BLOWN HEAD GASKET: A regular drop of fair magnitude can be caused by a blown head gasket or warped cylinder head to cylinder block surface.
15. RESTRICTED EXHAUST SYSTEM: When the engine is first started and is idled, the reading may be normal, but as the engine RPM is increased, the back pressure caused by a clogged muffler, kinked tail pipe or other concerns will cause the needle to slowly drop to 0 kPa (0 in-Hg). The needle then may slowly rise. Excessive exhaust clogging will cause the needle to drop to a low point even if the engine is only idling.

When vacuum leaks are indicated, search out and correct the cause. Excess air leaking into the system will upset the fuel mixture and cause concerns such as rough idle, missing on acceleration or burned valves. If the leak exists in an accessory such as the power brake booster, the unit will not function correctly. Always repair vacuum leaks.

Scheme 593

Scheme 594

Fuel Filler Cap

The fuel filler cap is used to prevent fuel spill and to close the EVAP system to the atmosphere.

Fuel Vapor Recirculation Tube (Duratec Engine Only)

The fuel vapor recirculation tube connects the fuel tank to the fuel filler pipe and allows recirculation of the fuel vapor from the fuel tank through the filler pipe with the dispensed fuel during refueling events. This reduces the volume of fuel vapors requiring storage in the EVAP canister.

Fuel Vapor Control Valve (Duratec Engine Only)

The fuel vapor control valve is normally between the EVAP canister and the fuel vapor vent valve. Its function is to prevent the flow of liquid fuel into the EVAP canister or up to the vapor management valve during refueling, and to prevent the collection of liquid fuel in the fuel vapor hoses by overfilling the fuel tank.

Fuel Tank Pressure (FTP) Sensor

The fuel tank pressure sensor is used to measure the fuel tank pressure during the Evaporative Emissions monitor test. It is also used to control excessive fuel tank pressures by forcing the EVAP system to purge. The fuel tank pressure sensor is tank-mounted.

Evaporative Emission (EVAP) Canister Purge Valve

The EVAP vapor management valve is controlled by the powertrain control module (PCM). The EVAP vapor management valve controls the flow of fuel vapors from the EVAP canister to the engine intake manifold during various engine operating modes. The EVAP vapor management valve is normally closed.

Canister Vent Solenoid

During the Evaporative Emission Running Loss System Monitor Test, Evaporative Emissions Repair Verification Drive Cycle, and the Evaporative Emission System Leak Test, the canister vent solenoid is closed to allow either a vacuum to be drawn on the fuel tank or to hold a specified pressure in the system. The canister vent solenoid is normally open.

Evaporative Emission (EVAP) Check Valve

The check valve vent is normally closed. When the EVAP system enters a purge cycle, the valve forces the purge air, being drawn in, to enter the system through the remote canister vent tube. During refueling the valve vent opens allowing the displaced air to vent freely to the atmosphere through a more direct and lower resistance path.

Dust Separator

The dust separator prevents dust and other contaminants from entering the EVAP system through the canister vent solenoid during purge cycles.

Evaporative Emission (EVAP) Canister

Fuel vapors from the fuel tank are stored in the EVAP canister. When the engine is running, the vapors are purged from the EVAP canister for combustion. OBD II vehicles sometimes use multiple canisters, which is dependent upon the size and number of the fuel tanks used on a specific vehicle.

Fuel Filler Pipe Check Valve

The fuel filler pipe check valve is an intricate part of the fuel tank or the fuel filler pipe. It is intended to prevent liquid fuel from re-entering the fuel filler pipe from the fuel tank on refueling.

Evaporative Emission System Monitor

When a fault occurs, the EVAP system monitor is reset to NO and a diagnostic trouble code (DTC) is set in the PCM memory. After the DTC is repaired, the vehicle drive cycle must be completed to reset the monitor in preparation for inspection and maintenance testing.

Note. The following procedure is designed to execute and complete the evaporative emission repair verification drive cycle and to clear the P1000, inspection and maintenance (I/M) readiness code. When the ambient air temperature is below 4.4°C (40°F) or above 37.8°C (100°F), or the altitude is above 2,438 meters (8,000 feet), the EVAP monitor will not run. If the P1000 must be cleared in these conditions, the powertrain control module (PCM) must detect them once (twice on some applications) before the EVAP monitor can be bypassed and the P1000 cleared. The EVAP bypassing procedure is described in the following drive cycle.

1. Most OBD II monitors will complete more readily using a steady foot driving style during cruise or acceleration modes. Operating the throttle in a smooth fashion will minimize the time necessary for monitor completion.
2. Fuel tank level should be between one-half and three-quarters full with three-quarters full being the most desirable.
3. The evaporative monitor can only operate during the first 30 minutes of engine operation. When executing the procedure for this monitor, stay in part throttle mode and drive in a smooth fashion to minimize fuel slosh. Drive Cycle Preparation NOTE: For best results, follow each of the following steps as accurately as possible. NOTE: This step bypasses the engine soak timer and resets OBD II monitor status.
4. Install the WDS or equivalent Tester. Turn the key ON with the engine OFF. Cycle the key off, then on. Select the appropriate vehicle and engine qualifier. Clear all diagnostic trouble codes (DTCs) and carry out a PCM reset.
5. Begin to monitor the following PIDs: ECT, EVAPDC, FLI (if available) and TP MODE. Press Diagnostic Data Link, PCM, PID/Data monitor and record, press trigger to select each PID, then start.
6. Start the engine without returning the key to the OFF position. Preparation For Monitor Entry WARNING: Strict observance of posted speed limits and attention to driving conditions are mandatory when proceeding through the following drive cycle. NOTE: This step allows engine warm-up and provides intake air temperature (IAT) input to the PCM.
7. Idle the vehicle for 15 seconds. Drive at 64 km/h (40 mph) until the ECT is at least 76.7°C (170°F).
8. Is IAT above 4.4°C (40°F) and below 37.8°C (100°F)? If not, continue with the following steps but note that the EVAP Monitor Bypass portion of the drive cycle (step 13 ) will be required to bypass the EVAP monitor and clear the P1000. NOTE: This step executes the heated oxygen sensor (HEGO) monitor.
9. Cruise at 64 km/h (40 mph) for 60 seconds. NOTE: This executes the EVAP monitor if IAT is above 4.4°C (40°F) and below 37.8°C (100°F). NOTE: To initiate the monitor, TP MODE should equal PT, EVAPDC must be greater than 75%, and FLI must be between 15 and 85%. NOTE: Avoid sharp turns and hills.
10. Cruise at 72 to 104 km/h (45 to 65 mph) for 10 minutes. NOTE: This step executes the ISC portion of the Secondary Air/CCM.
11. Bring the vehicle to a stop. Idle with the transaxle in DRIVE (for automatic transaxle) or NEUTRAL (for manual transaxle) for two minutes. Pending Code Check And EVAP Monitor Bypass Check NOTE: This determines if a pending code is preventing the clearing of P1000. NOTE: If the EVAP monitor is not complete and IAT was below 4.4°C (40°F) or above 37.8°C (100°F) temperature range in step 8 , or the altitude is above 2,438 meters (8,000 feet), the EVAP Monitor Bypass (step 13) must be carried out.
12. Using the WDS or equivalent Tester, check for pending codes. Conduct normal repair procedures for any pending code concerns. Rerun any incomplete monitor. EVAP Monitor Bypass NOTE: This allows the bypass counter to increment to two. NOTE: Do not repeat step 4.
13. Park the vehicle for a minimum of eight hours. Repeat steps 5 through 12 .

CANISTER VENT SOLENOID CLOSING PROCEDURE

1. Connect the WDS or equivalent Tester and select the output test mode.
2. Select the EVAPCU PID.
3. Select the ALL OFF mode.
4. Close the canister vent solenoid by pushing the START button on the WDS or equivalent Tester.

CHARGING SYSTEM

Refer to STARTING/CHARGING for schematic information.

Scheme 595

Scheme 596

Functionality (Duratec Engine Only)

With the ignition switch in the ON position, voltage is applied through the warning indicator I circuit (LG/R) to the voltage regulator. This turns the regulator on, allowing current to flow from battery sense A circuit (B/Y) to the generator field coil. When the engine is started, the generator begins to generate alternating current (AC) which is internally converted to direct current (DC). This current is then supplied to the vehicle's electrical system through the output (B+) terminal of the generator.

Once the generator begins generating current, a voltage signal is taken from the generator stator and fed back to the regulator internally. This voltage feedback signal (typically half the battery voltage) is used to turn off the warning indicator.

With the system functioning normally, the generator output current is determined by the voltage of the A circuit. The A circuit voltage is compared to a set voltage internal to the regulator, and the regulator controls the generator field current to maintain the correct generator output.

The set voltage will vary with temperature and is typically higher in cold temperatures and lower in warm temperatures. This allows for better battery recharge in the winter and reduces the chance of overcharging in the summer.

Battery Positive Output Circuit (B+) 36 (Y/W)

The generator output is supplied through the battery positive output (B+) terminal on the back of the generator to the battery and electrical system.

I Circuit (LG/R)

The I (ignition) circuit is used to turn on the voltage regulator. This circuit is powered up with the ignition key in the RUN position. This circuit is also used to turn the charging system warning indicator on if there is a fault in the charging system operation.

A Circuit (B/Y)

The A circuit or battery sense circuit is used to sense battery voltage. This voltage is used by the regulator to determine generator output. This circuit is used to supply current to the generator field (rotor). The amount of current supplied to the rotor will determine generator output.

COMPONENT TESTS

Battery - Load Test

1. With the engine running, turn the A/C on, the blower motor on high speed and the headlamps on high beam.
2. Increase the engine speed to approximately 2,000 RPM. The voltage should increase a minimum of 0.5 volt above the base voltage. If the voltage does not increase as specified, carry out «GENERATOR ON-VEHICLE TESTS»(ref-178490-S40122356352005061600000) . If the voltage increases as specified, the charging system is operating normally. Battery - Drain Tests NOTE: No production vehicle should have more than a 50 mA (0.050 amp) continuous draw. Check for current drains on the battery in excess of 50 milliampere (0.050 amp) with all the electrical accessories off and the vehicle at rest. Current drains can be tested with the following procedure: WARNING: Do not attempt this test on a lead-acid battery that has recently been recharged. Explosive gases can cause personal injury. CAUTION: To prevent damage to the meter, do not crank the engine or operate accessories that draw more than 10A. NOTE: Many modules draw 10 mA (0.010 amp) or more continuously. NOTE: Use an in-line ammeter between the battery positive or negative post and its respective cable. NOTE: Typically, a drain of approximately one amp can be attributed to an engine compartment lamp, glove compartment lamp, or luggage compartment lamp staying on continually. Other component failures or wiring shorts may be located by selectively pulling fuses to pinpoint the location of the current drain. When the current drain is found, the meter reading will fall to an acceptable level. If the drain is still not located after checking all the fuses, it may be due to the generator. NOTE: To accurately test the drain on a battery, an in-line digital ammeter must be used. Use of a test lamp or voltmeter is not an accurate method due to the number of electronic modules.
3. Make sure the junction box/fuse panels are accessible without turning on interior and underhood lights.
4. Drive the vehicle at least five minutes and over 48 km/h (30 mph) to turn on and exercise the vehicle systems.
5. Allow the vehicle to sit with the key off for at least 40 minutes to allow modules to time out/power down.
6. Connect a fused jumper wire between the negative battery cable and the negative battery post to prevent modules from resetting and to catch capacitive drains.
7. Disconnect the negative battery cable from the post without breaking the connection of the jumper wire. NOTE: It is very important that continuity is not broken between the battery and the negative battery cable when connecting the meter. If this happens, the entire procedure must be repeated.
8. Connect the tester between the negative battery cable and the post. The meter must be capable of reading milliampere and should have a 10 amp capability. NOTE: If the meter settings need to be switched or the test leads need to be moved to another jack, the jumper wire must be reinstalled to avoid breaking continuity.
9. Remove the jumper wire. NOTE: Amperage draw will vary from vehicle to vehicle depending on the equipment package. Compare to a comparable vehicle for reference. NOTE: No production vehicle should have more than a 50 mA (0.050 amp) draw.
10. If the draw is found to be excessive, pull fuses from the battery/central junction box one at a time and note the current drop. Do not reinstall the fuses until you are finished testing.
11. Check «STARTING/CHARGING»(ref-168549-S26303884852004111000000) wiring diagrams for any circuits that run from the battery without passing through the battery/central junction box. Disconnect these circuits if the draw is still excessive.

Battery - Electronic Drains Which Shut Off When the Battery Cable is Disconnected

1. Repeat the steps of the battery drain testing.
2. Make sure all doors are closed and accessories are off. Without starting the engine, turn the ignition switch to RUN for a moment and then OFF. Wait a few minutes for the illuminated entry lamps to turn off if equipped.
3. Connect the ammeter and read the amperage draw. The current reading (current drain) should be less than 50 mA (0.05 amp). If the current drain exceeds 50 mA (0.05 amp) after a few minutes, and if this drain did not show in previous tests, the drain is most likely caused by an inoperative electronic component. As in previous tests, remove the fuses from the battery/central junction box one at a time to locate the problem circuit.

Generator On-Vehicle Tests

Note. Battery posts and cable clamps must be clean and tight for accurate meter indications.

Note. Refer to the battery tester manual for complete directions for testing the charging system.

1. Turn off all lamps and electrical components.
2. Place the transaxle range selector lever in NEUTRAL and apply the parking brake.
3. Carry out the «GENERATOR ON-VEHICLE TESTS - LOAD TEST»(ref-178490-S38954891532005061600000) and «GENERATOR ON-VEHICLE TESTS - NO LOAD TEST»(ref-178490-S36719840082005061600000) according to the following component tests

Scheme 597

1. Switch the battery tester to the ammeter function.
2. Connect the positive and negative leads of the battery tester to the corresponding battery terminals.
3. Connect the current probe to the generator B+ output terminal, circuit (Y/W).
4. With the engine running, turn the A/C on, the blower motor on high speed and the headlamps on high beam.
5. Increase the engine speed to approximately 2,000 RPM. The voltage should increase a minimum of 0.5 volt above the base voltage. If the voltage does not increase as specified, carry out the Generator On-Vehicle Tests. For additional information, refer to «GENERATOR ON-VEHICLE TESTS - No Load Test»(ref-178490-S36719840082005061600000) . If the voltage increases as specified, the charging system is operating normally.
6. Adjust the tester load bank to determine the output of the generator. Generator output should be at least 58 amps.

Starter Motor - Motor Feed Circuit

Note. Make all multimeter connections at the component terminal rather than the cable or wiring terminal.

Scheme 598

1. Make sure the battery is fully charged. Carry out a battery load test. For additional information, refer to «CHARGING SYSTEM»(ref-178490-S07465532032005061600000) .
2. Disconnect the ignition coil connector.
3. Connect a remote starter switch between the starter solenoid S-terminal and the battery positive (+) post.
4. Connect the positive (+) lead of digital multimeter to the battery positive (+) post. Connect the negative (-) lead of the multimeter to the starter solenoid M-terminal.
5. Engage the remote starter switch. Read and record the voltage. The multimeter reading should be 0.5 volt or less.
6. If the voltage reading is 0.5 volt or less, go to t «STARTER MOTOR - GROUND CIRCUIT TEST»(ref-178490-S27569663552005061600000) .
7. If the voltage reading is greater than 0.5 volt, this is an indication of excessive resistance in the connections, the positive battery cable or in the starter solenoid. Move the digital multimeter negative lead to the starter solenoid B-terminal and repeat the test. If the voltage reading at the B-terminal is lower than 0.5 volt, the concern is either in the connections at the starter solenoid or in the solenoid contacts.
8. Remove the cables at the starter solenoid B-, S-, and M-terminals. Clean the connections and install the cables. Repeat Steps 3 through 6 above. If the reading is still higher than 0.5 volt at the M-terminal and 0.5 volt or lower at the B-terminal, the concern is the solenoid contacts. Install a new starter motor. Refer to STARTER MOTOR - 2.0L ZETEC , or STARTER MOTOR -3.0L DURATEC (4V) .
9. If the voltage measured in Step 5 is greater than 0.5 volt, the concern is either the positive (+) battery cable connection or the positive (+) battery cable itself. Clean the positive (+) battery cable connection. If this does not solve the problem, install a new positive battery cable.

2.0L

IGNITION SCOPE TEST 2.0L

Scheme 599

3.0L

IGNITION SCOPE TEST

Scheme 600

Scheme 601

Scheme 602

Scheme 603

Scheme 604

Scheme 605