Engine Controls - Tests W/codes - Eec Ford Escort V

INTRODUCTION

Before proceeding with this article, ensure steps in BASIC TESTING article have been performed. If no faults were found while performing procedures in the BASIC TESTING article, proceed with self-diagnostics. If no fault codes are present after entering self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.).

HARD FAILURES

Hard failures cause CHECK ENGINE light to come on and trouble code(s) to be set in ECA memory. Trouble code(s) remain until problem is repaired. To retrieve trouble code(s), see RETRIEVING CODES in this article. Use diagnostic (code) charts to determine the cause of malfunction.

If a sensor fails, the ECA will use a substitute value in its calculations to continue engine operation. The ECA can estimate failed sensor values based on feedback from working sensor(s). In this condition, commonly known as Limited Operating Strategy (LOS), the vehicle runs but driveability will not be optimum.

INTERMITTENT FAILURES

Intermittent failures may cause CHECK ENGINE light to flicker or illuminate. Light will go out after intermittent fault goes away. These faults indicate a defect that may or may not be present at the time of testing, however, the corresponding trouble code will be retained in ECA memory.

If related fault does not reoccur within a certain time frame, the trouble code will be erased from ECA memory. Intermittent failures may be caused by a sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article.

Scheme 75

RETRIEVING CODES

Codes, from EEC system, are retrieved through the Self-Test connector using the following self-test procedures: Key On Engine Off (KOEO) and Key On Engine Running (KOER). See SELF-TEST PROCEDURES . If no code or only intermittent fault is found after performing KOEO and KOER self-test procedures, proceed to SWITCH MONITOR TEST .

VISUAL CHECK & VEHICLE PREPARATION

Before hooking up any equipment to diagnose EEC system, visually check the following and perform the preparation procedures

1. Check condition of air cleaner and air ducting.
2. Perform all necessary safety precautions to prevent personal injury or vehicle damage.
3. Block drive wheels. Set parking brake; place shift lever in Park for A/T vehicles, and Neutral for M/T vehicles. DO NOT move shift lever during test unless specifically directed to do so.
4. Check all vacuum hoses for leaks, restrictions and proper routing.
5. Check EEC system wiring harness connections for corrosion, damaged pins, loose wires and proper routing.
6. Check ECA, sensors and actuators for physical damage.
7. Check engine coolant and oil level.
8. Turn off all lights and accessories. Ensure vehicle doors are closed when measuring voltage or resistance.
9. Start engine and idle until upper radiator hose is hot and pressurized. Check for leaks around exhaust manifold and exhaust gas oxygen sensor.

SELF-TEST PROCEDURES

Note. The accuracy of self-test data depends on correct operation of non-EEC components and systems. All non-EEC problems in the engine, ignition or fuel system must be corrected before attempting to diagnose the EEC system.

Perform Key On Engine Off (KOEO) and Key On Engine Running (KOER) self-test procedures with one of the following: SUPER STAR II tester, analog volt-ohmmeter (VOM), or CHECK ENGINE light.

KOEO codes include hard and intermittent failures. To determine failure(s) type (hard or intermittent), record and clear codes stored in ECA memory. Operate vehicle and repeat KOEO self-test. Codes that immediately reappear are hard failures. Codes that do not reappear are intermittent failures.

Repair hard failures, in the order of code appearance, before performing KOER self-test. Use CODE REFERENCE CHART to determine the correct CIRCUIT TEST. Codes may be cleared from the ECA memory after they have been recorded and/or faults repaired. See CLEARING CODES. If no trouble codes are found during KOEO self-test, proceed to KOER self-test.

Note. The EEC system will not display a PASS code.

CODE-TO-TEST MENU

CODE-TO-TEST REFERENCE CHART

ANALOG VOLT-OHMMETER (VOM)

1) Turn ignition off. To initiate KOEO self-test, connect a jumper wire from self-test connector STI terminal to ground. The STI connector is located at the left rear of the engine compartment. (Scheme 76)and (Scheme 77).

2) Set VOM at 0-20V DC range. Connect positive (+) lead of VOM to self-test connector STO terminal. Connect the negative (-) test lead to engine ground. (Scheme 77)and (Scheme 78).

3) Turn ignition on and observe voltmeter. Count voltmeter needle sweeps (between 0-12 volts). (Scheme 75) Record codes displayed, turn ignition off, and go to step 4). If no code is present and engine start, begin KOER self-test; see step 7).

Note. If no code is present and engine will not start, go to BASIC TESTING article in this section.

4) Erase codes from ECA memory. See CLEARING CODES . Repeat step 3) to identify hard faults. If code(s) reappears, indicating it is a hard fault, repair fault as necessary. Refer to CODE REFERENCE CHART to determine the correct CIRCUIT TEST. Go to step 6).

5) If code(s) does not reappear, fault is intermittent. Start KOER self-test. See step 7).

6) Repeat step 4) until no code appears. Terminate KOEO self-test by turning ignition off and disconnecting STI jumper wire from ground. Start KOER self-test; see step 7).

7) Start engine and run at 2000 RPM for 2 MINUTES to ensure EGO sensor is operating. Ensure vehicle is at normal operating temperature. Turn ignition off. Jumper STI connector to ground to activate KOER self-test. Turn ignition on and wait 10 SECONDS.

8) Start engine and allow to idle. Ensure VOM is connected as described in step 2). Record all codes displayed and repair fault as necessary. Refer to CODE REFERENCE CHART to determine the correct CIRCUIT TEST. If no code is present, go to ANALOG VOLT-OHMMETER (VOM) under SWITCH MONITOR TEST .

CHECK ENGINE LIGHT

1) Connect a jumper wire between the STI connector and ground. (Scheme 76)and (Scheme 77). Turn ignition on. Observe CHECK ENGINE light. Record pulses to determine KOEO codes stored. Go to step 3).

Note. Reading code from ENGINE LIGHT pulses is similar to reading code from needle sweep of Analog Volt-Ohmmeter (VOM). See ANALOG VOLT-OHMMETER (VOM) under SELF-TEST.

2) If no code is present and engine starts, begin KOER self-test; see step 6). If no code is present and engine does not start, go to the BASIC TESTING article.

3) Erase code from ECA memory. See CLEARING CODES. Repeat step 1) to identify hard faults. If code(s) reappear, indicating it is a hard fault, repair fault as necessary. See CODE REFERENCE CHART to determine the correct CIRCUIT TEST. Go to step 5).

4) If code(s) does not reappear, fault is intermittent. Start KOER self-test. See step 6).

5) Repeat step 3) until no code appears. Terminate KOEO self-test by turning ignition off and disconnecting jumper wire from STI connector. Start KOER self-test; see step 6).

6) Start engine and run at 2000 RPM for 2 minutes to ensure EGO sensor is operating. Ensure vehicle is at normal operating temperature. Jumper STI connector to ground. Observe CHECK ENGINE light. Record pulses to determine KOER codes stored. Use CODE-TO-TEST MENU to determine the appropriate CIRCUIT TEST.

SUPER STAR II TESTER

1) To initiate KOEO self-test, turn ignition off. Connect color-coded adapter cable leads to SUPER STAR II tester. Connect service adapter cables to vehicle self-test connectors.

2) On Escort and Tracer, use Harness Adaptor (007-00049) between adapter cables and vehicle self-test connectors. Slide adaptor switch to EEC position. On Probe, ground adapter cable. On all models, slide switch SUPER STAR II tester to MECS position.

3) Set center button in TEST position. On Probe, turn ignition on. Turn SUPER STAR II tester on. When activated, tester should display 888 for 2 seconds. On Escort and Tracer, turn ignition on.

4) On all models, release and reset button in TEST position. After all codes have been received by tester, release center button. Retrieve and record all codes in tester memory. Go to step 5). If no code exists and engine starts, begin KOER self-test; see step 8).

Note. If no code is present and engine does not start, go to BASIC TESTING article in this section.

5) Erase codes from ECA memory. See CLEARING CODES. Repeat steps 3) and 4) to identify hard faults. If code(s) reappear, indicating it is a hard fault, repair as necessary. Refer to CODE REFERENCE CHART to determine the appropriate CIRCUIT TEST. Go to step 7).

6) If code(s) does not reappear, fault is intermittent. Begin KOER self-test; see step 8).

7) Repeat step 5) until no code appears. Turn ignition off. Start KOER self-test; see step 8).

8) To initiate KOER self-test. Ensure center button on SUPER STAR II tester is unlatched. Start engine and run at 2000 RPM for 2 minutes to ensure EGO sensor is operating. Turn SUPER STAR II tester on. Set center button in TEST position. Turn ignition off. Start engine and let it idle.

9) To activate KOER self-test, release and reset button in the TEST position. Record all codes displayed. Refer to CODE REFERENCE CHART to determine appropriate CIRCUIT TEST. If no code is displayed, go to SUPER STAR II TESTER under SWITCH MONITOR TEST.

Scheme 76

SWITCH MONITOR TEST

Perform this test if no code is present after performing KOEO and KOER self-tests. Switch monitor tests determine if electrical signals to the ECA from input devices are correct. In this procedure, each device is tested individually. Perform test with SUPER STAR II tester or Analog Volt-Ohmmeter (VOM).

SWITCH MONITOR TEST SPECIFICATIONS

1) Turn engine off and allow to cool. Turn all accessories off. Disconnect STI jumper from ground. Place shift lever in Park for A/T vehicles, and Neutral for M/T vehicles.

2) Using a jumper wire, connect self-test connector STI terminal to ground. (Scheme 76)and (Scheme 77). Using an analog VOM, connect positive (+) lead to self-test connector SML terminal. (Scheme 77)and (Scheme 78). Connect the negative (-) test lead to engine ground.

3) Turn ignition on. Test EEC input devices individually. See SWITCH MONITOR TEST SPECIFICATIONS . Ensure input device is deactivated after test. Leaving device on while testing another device may produce false results and cause misdiagnosis.

4) If input device fails test (reading or VOM is not as indicated), perform related CIRCUIT TEST. See SWITCH MONITOR TEST SPECIFICATIONS . If all input devices test okay and no code is stored in ECA memory, EEC system test is complete.

1) Turn engine off and allow to cool. Turn all accessories off. Connect tester as described in SUPER STAR II TESTER under SELF-TEST. Ensure tester center button is released.

2) Place shift lever in Park for A/T vehicles, and Neutral for M/T vehicles. Turn tester on and set center button to TEST position. Observe LED indication as each input device is tested. See SWITCH MONITOR TEST SPECIFICATIONS .

3) Test EEC input devices individually. Turn device off after test. Leaving device on while testing another device may produce false results and cause misdiagnosis. If input device fails test (reading on SUPER STAR II tester is not as indicated), perform related CIRCUIT TEST. See SWITCH MONITOR TEST SPECIFICATIONS . If all input devices test okay and no code is stored in ECA memory, EEC system test is complete.

Scheme 77

Scheme 78

CLEARING CODES

To clear trouble codes, deactivate self-test by disconnecting jumper wire from STI connector. Disconnect negative (-) battery cable and depress brake pedal for 5-10 seconds. All hard codes and intermittent codes will be erased from ECA memory.

SELF-TEST CONNECTOR LOCATION

SUMMARY

If no hard fault codes are present, driveability symptoms exist or intermittent codes exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

HOW TO USE CIRCUIT TESTS

1) DO NOT perform any CIRCUIT TEST unless specifically instructed by a procedure under SELF-TEST or SWITCH MONITOR TEST. Ensure all non-EEC related faults are corrected. FOLLOW EACH TEST STEP IN ORDER UNTIL FAULT IS FOUND. When more than one code is received, start with the first code displayed.

2) CIRCUIT TESTS check electrical circuits to make sure they are okay before replacing sensors or any other components. Always test circuits for continuity between sensor and ECA. Test all circuits for short to power, opens, or short to ground.

3) DO NOT connect any test light, or measure voltage or resistance at ECA unless specified in testing procedure. DO NOT pierce wiring. If backprobing is specified, always backprobe harness side of connector; DO NOT probe connector side.

4) Isolate both ends of circuit and turn key off whenever checking for shorts or continuity, unless specified otherwise. Disconnect solenoids and switches before checking circuit continuity, or energizing solenoids.

Note. A short is defined as a resistance value of less than 5 ohms.

Scheme 79

Scheme 80

TEST EQUIPMENT

The following equipment is recommended to diagnose and test the EEC system. DO NOT attempt to test this system without proper equipment. Damage to vehicle components may result if improper equipment is used.

1. The Self-Test Automatic Read-Out (SUPER STAR II) diagnostic tester is recommended but not required. It is specially built for EEC systems and is used to display the 2-digit (numeric) codes programmed into control module. Aftermarket "Scan" tools are also available.
2. Analog Volt-Ohmmeter (VOM) with 0-20V DC range can be used, as an alternative to diagnostic tester, to read codes.
3. Digital Volt-Ohmmeter (DVOM) with minimum 10-megohm input impedance.
4. A breakout box is required to perform certain tests on system. The test pin No. mentioned in CIRCUIT TESTS refers to test pin numbers on breakout box. Once the breakout box has been installed during a test sequence, it may remain connected for the remainder of that test, unless stated otherwise. Aftermarket breakout boxes are also available.
5. Vacuum gauge with 0-30 in. Hg range and resolution (units on scale) of 1 in. Hg.
6. Tachometer with 0-6000 RPM range, +/- 40 RPM accuracy, and a resolution of 20 RPM
7. Vacuum pump with 0-30 in. Hg range
8. Timing light
9. Spark Tester (D81P-6666-A or ST-125) is required. A modified side electrode spark plug IS NOT sufficient for these testing procedures.
10. Fuel Injection Pressure Gauge (T80L-9974-A)
11. 12-volt test light (non-powered type)
12. Jumper wire about 15" long

Note. In the following tests, circuits and illustrations are provided by Ford Motor Co. Complete EEC system wiring diagrams may be found in WIRING DIAGRAMS article.

CIRCUIT TEST INFORMATION

Due to the limited space available on the menu screen, the following CIRCUIT TEST titles have been shortened to TEST. This allow for a more complete explanation of the test to appear on the menu. When referred to "CIRCUIT TEST STG", for example, look for the title "TEST STG".

TEST BP - BAROMETRIC PRESSURE SENSOR

Note. Enter this test only when Code 14 is displayed during SELF-TEST procedures, or when directed here from another CIRCUIT TEST. To prevent unnecessary replacement of components, check for fault in the following non-EEC items: atmospheric barometer reading (unusually high or low), vacuum lines (blocked), and basic mechanical engine components.

Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, erase codes from memory. Perform KOEO and KOER self-tests. See SELF-TEST. If Code 14 continues to appear, replace ECA.

Note. The barometric pressure sensor is built into the ECA and cannot be replace separately. If Code 14 appears repeatedly after clearing codes, replace ECA.

TEST CID1 - CYLINDER IDENTIFICATION NO. 1

Note. Enter this test only when Code 03 is displayed during SELF-TEST procedures, or when directed here from another CIRCUIT TEST. This test is intended to diagnose only the following: CID1, CIDREF, VPWR and distributor ground.

Identifying CID1 Connector Terminals. Scheme 81

CIRCUIT PIN IDENTIFICATION (CID1)

Note. The CID is incorporated with the Crankshaft Position Sensor (CPS) inside the distributor.

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking CID1 Circuit Resistance Turn ignition off. Install breakout box, leaving ECA disconnected. Disconnect distributor connector. On 1.8L engines, check resistance of CID1 (Yellow/Blue wire), VPWR (White/Red wire) and GND (Black/Orange wire) circuits between ECA and distributor. On 2.2L engines, check resistance of CID1 (Green wire) and CIDREF (White wire) circuits between ECA and distributor. On all models, if resistance is more than 5 ohms, repair circuit. If resistance is not more than 5 ohms, go to next step.

3) Checking CID1 Circuit Voltage Install breakout box, and leave ECA disconnected. On 1.8L engines, measure voltage between CID1 and GND test pins while cranking engine. If voltage is 1.5 volts, replace ECA. If voltage is not 1.5 volts, go to step 4). On 2.2L engines, measure voltage between CID1 and CIDREF test pins while cranking engine. If voltage is 0.6-0.8 volt, replace ECA. If voltage is not 0.6-0.8 volt, go to CIRCUIT TEST VPWR.

4) Checking Voltage To Distributor (1.8L) Disconnect distributor connector. Measure resistance between VPWR and ground. If voltage is less than 10 volts, go to CIRCUIT TEST VPWR. If voltage is more than 10 volts, measure resistance between VPWR and GND wire. If voltage is less than 10 volts, repair GND circuit wire. If voltage is more than 10 volts, replace CID1 sensor.

TEST CID2 - CYLINDER IDENTIFICATION NO. 2

Note. Enter this test only when Code 04 is displayed during SELF-TEST procedures, or when directed here from another CIRCUIT TEST. This test is intended to diagnose only the following: CID1 and CIDREF.

Identifying CID2 Connector Terminals. Scheme 82

CIRCUIT PIN IDENTIFICATION (CID2)

Note. The CID is incorporated with the Crankshaft Position Sensor (CPS) inside the distributor.

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking CID2 Circuit Resistance Turn ignition off. Install breakout box, leaving ECA disconnected. Set DVOM on 1000-ohm scale. Check resistance between CID2 and CIDREF test pins. If resistance is 210-260 ohms, go to step 3). If resistance is not as specified, go to step 4).

3) Checking CID2 Circuit Voltage With ECA disconnected, measure voltage between test pins of CID2 and CIDREF breakout box while cranking engine. If voltage is not 0.6-0.8 volt, replace CID2 sensor. If voltage is 0.6-0.8 volt, circuit is okay. Repeat KOEO self-test. See SELF-TEST. If no other faults or codes are found, replace ECA.

4) Checking CID1 Sensor Resistance With key off, disconnect distributor connector. Measure resistance between CID2 (Red wire) and CIDREF (White wire) terminals. If resistance is 210-260 ohms, repair CID2 or CIDREF circuit from distributor to ECA. If resistance is not 210-260 ohms, replace CID2 sensor.

TEST CPS - CRANKSHAFT POSITION SENSOR

Note. Enter this test only when Code 02 is displayed during SELF-TEST procedure, or when directed here from another CIRCUIT TEST.

Identifying CPS Connector Terminals. Scheme 83

CIRCUIT PIN IDENTIFICATION (CPS)

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking Resistance Of CPS Circuit Turn ignition off. Install breakout box, leaving ECA disconnected. Disconnect distributor connector. On 1.8L engines, measure resistance between ECA and distributor of the following circuits: CPS (White wire) VPWR, (White/Red wire) and GND (Black/Orange wire) terminals. On 2.2L turbo engines, measure resistance between ECA and distributor of the following circuits: CPS (Blue wire) and CIDREF (White wire) terminals. If resistance is more than 5 ohms, repair circuit between distributor to ECA. If resistance is less than 5 ohms, go to step 3).

3) Checking CPS Input Voltage On 1.8L engines, measure voltage between CPS and GND test pins while cranking engine. If voltage is 1.5 volts, replace ECA. If voltage is not as specified, go to step 3). On 2.2L turbo engines, measure voltage between CPS and CIDREF test pins while cranking engine. If voltage is 0.6-0.8 volt, replace ECA. If voltage is not as specified, perform TEST VPWR.

4) Checking Voltage To Distributor (1.8L) Disconnect distributor connector. Turn ignition on. Measure resistance between VPWR and ground. If voltage is less than 10 volts, go to CIRCUIT TEST VPWR. If voltage is more than 10 volts, measure resistance between VPWR and GND wire. If voltage is less than 10 volts, repair GND circuit wire. If voltage is more than 10 volts, replace CPS sensor.

TEST ECT - ENGINE COOLANT TEMPERATURE SENSOR

Note. Enter this test only when a Code 09 is displayed during SELF-TEST procedure, or when directed here from another CIRCUIT TEST. To prevent unnecessary diagnosis, inspect coolant level, oil level, cooling fan, thermostat and airflow to radiator for obstruction before electronic testing.

Identifying ECT Connector Terminals. Scheme 84

CIRCUIT PIN IDENTIFICATION

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking ECT Circuit Ensure engine is at operating temperature.Turn ignition off. Install breakout box, leaving ECA disconnected. Disconnect ECT sensor connector. Turn ignition on. Measure voltage between ECT test pin and ECT connector terminal (Blue/White wire on 1.8L; Yellow/Black wire on 2.2L). If continuity is not present, repair circuit between ECA and ECT sensor. If continuity is present, go to step 3).

3) Checking SIGRTN Resistance With key off, disconnect ECT sensor. Check for continuity between SIGRTN terminal of ECT connector and SIGRTN test pin. If continuity is not present, repair circuit. If continuity is present, go to step 4).

4) Checking ECT Ground Circuit With key off, check for continuity between SIGRTN and GND test pins. If continuity is not present, repair circuit as necessary. If continuity is present, disconnect ECT sensor. Measure sensor resistance.

5) ECT Sensor Resistance Compare resistance to specifications shown in RESISTANCE SPECIFICATIONS (ECT SENSOR) . If resistance is as specified, replace ECT sensor. If resistance is within specification, measure resistance between ECT and SIGRTN test pins. If resistance is 500-1000 ohms, replace ECA. If resistance is not 500-1000 ohms, replace ECT sensor.

RESISTANCE SPECIFICATIONS

TEST EGO - EXHAUST GAS/OXYGEN SENSOR

CIRCUIT PIN IDENTIFICATION

Note. Enter this test only when a Code 15 (lean) or Code 17 (rich) is displayed during SELF-TEST procedure. This test is intended to diagnose only the EGO circuit.

1) Checking System Integrity Visually check wiring, connector and component for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking EGO Sensor Output Voltage Warm engine to operating temperature and let idle. Disconnect EGO sensor. Measure voltage between EGO sensor lead wire and ground. With engine at idle, voltage should be 0.2-0.8 volt.

3) Rapidly increase and decrease engine speed while reading voltmeter. When engine speed is increased, voltage should increase. When engine speed is decreased, voltage should decrease. If voltage is as specified, go to step 4). If voltage is not as specified, replace EGO sensor.

4) Isolating Open Circuit in EGO Sensor Turn ignition off. Install breakout box, leaving ECA disconnected. Disconnect EGO sensor connector. Measure continuity between EGO test pin and EGO sensor connector terminal. If continuity is present, EGO circuit is okay. If continuity is not present, repair circuit between EGO sensor and ECA.

TEST EVP - EGR VALVE POSITION SENSOR

Note. Enter this test only when a Code 16 is displayed during SELF-TEST procedure, or when directed here from another CIRCUIT TEST. This test is intended to diagnose only the EVP circuit on 2.2L engines.

Identifying EVP Connector Terminals. Scheme 85

CIRCUIT PIN IDENTIFICATION (EVP)

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking EGR Voltage Ensure engine is at operating temperature. Turn ignition off. Install breakout box, leaving ECA disconnected. Install vacuum pump to EGR vacuum port. Attach voltmeter to EVP and SIGRTN test pins. Turn ignition on.

3) Slowly apply vacuum to EGR valve. Compare voltmeter readings to specifications shown in EVP SENSOR SPECIFICATIONS . If voltage is within specification, EVP circuit is okay; fault is in another circuit or ECA. If voltage is not within specification, go to step 4).

4) Checking EGR Signal Return Remove EVP sensor connector. Using jumper wire, attach connector VREF (Green/Red wire) and SIGRTN (Green/Yellow wire) back to matching terminal on EVP sensor. Install vacuum pump to EGR vacuum port.

5) Attach voltmeter to EVP and SIGRTN terminal on EVP sensor. Turn ignition on. Slowly apply vacuum to EGR VALVE. Compare voltage to specifications shown in VOLTAGE SPECIFICATIONS (EVP SENSOR) . If voltage is within specification, repair EVP circuit between sensor and ECA.

6) Checking SIGRTN/VREF At EGR If voltage is not to specification, turn ignition on. Measure voltage, at wiring harness connector, between VREF terminal (Green/Red wire) and SIGRTN terminal (Green/Yellow wire) of connector. If voltage is 4.5-5.5 volts, replace EVP sensor. If voltage is not as specified, go to CIRCUIT TEST VREF.

VOLTAGE SPECIFICATIONS

TEST IDM - IGNITION DIAGNOSTIC MONITOR

Note. Enter this test only when Code 01 is displayed during SELF-TEST procedures. This test is intended to diagnose only the following: EEC system related spark and electrical circuits (IDM, SPOUT, PIP and VPWR to ignition).

Identifying IDM Connector Terminals. Scheme 86

CIRCUIT PIN IDENTIFICATION (IDM)

1) Checking System Integrity Visually check all wiring, connectors and components for damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking Coil IDM To ECA Circuit Connect spark tester between coil secondary cable and ground. Crank engine. If spark is present on 1.8L engines, and no other faults except for Code 01 is found, replace ECA. If spark is present on 2.2L non-turbo engines, go to step 3). If spark is present on 2.2L turbo engines, go to step 11).

3) IDM to ECA (2.2L Non-Turbo) Install breakout box, leaving ECA disconnected. Connect test light between IDM and PWR test pins. Crank engine. If test light flashes, IDM circuit is okay. If test light does not flash, repair IDM circuit between ignition coil and ECA.

4) Continuous IDM At Coil Disconnect ignition coil connector. Connect test light between ignition coil IDM wire (Yellow/Black wire on 1.8L; Blue/Red wire on 2.2L turbo; Yellow/Blue wire on 2.2L non-turbo) and PWR wire (Black/Orange wire on 1.8L; Black/White wire on 2.2L). Crank engine. If test light flashes, go to step 5). If test light does not flash, go to step 7).

5) Power To Ignition Coil Disconnect ignition coil connector. Turn ignition on. Measure voltage between ignition coil PWR wire and ground. On all except turbo engines, if voltage is greater than 10 volts, replace coil. If reading is not greater than 10 volts, repair PWR circuit between ignition coil and ignition switch.

6) On turbo engines, connect test light between ignition coil PWR terminal and GND terminal. Turn ignition on. If test light comes on, replace ignition coil. If test light does not come on, repair ignition coil ground circuit.

7) Continuous IDM From Ignition Module Disconnect ignition module connector. On 1.8L engines, connect jumper wire between disconnected SPOUT terminals and GND terminals. On 2.2L non-turbo engines, connect jumper wire between disconnected PWR terminals. On 2.2L turbo engines, connect jumper wire between disconnected PIP, SPOUT, VPWR and GND terminals. On all models, connect test light between IDM terminal and VPWR (2.2L turbo) or PWR (all others).

8) Crank engine. If test light flashes as engine is cranked, repair IDM wire between ignition module and coil. If light does not flash on 1.8L engines, go to step 9). If light does not flash on 2.2L engines, measure voltage between ground and VPWR wire (2.2L turbo) or PWR wire (all others). If voltage is less than 10 volts, repair VPWR wire (2.2L turbo) or PWR wire (all others). If voltage is more than 10 volts, replace ignition module (2.2L non-turbo) or go to step 9) (2.2L turbo).

9) Ignition Module Ground (1.8L & 2.2L Turbo) Remove ignition module connector. Connect test light between VPWR and GND terminals of connector. Turn ignition on. If light does not come on, repair ignition module ground wire. If light comes on for 1.8L engines, go to step 11). If light comes on for 2.2L turbo engines, connect analog voltmeter between ignition module connector PIP terminal and ground. Set meter on 5-volt scale. Crank engine. Verify voltmeter needle pulses. If voltage is pulsing, go to step 11). If voltage is not pulsing, go to step 10).

10) PIP Circuit From ECA Install breakout box, leaving ECA disconnected. Check for continuity between PIP test pin and PIP terminal at ignition module. If continuity is not present, repair PIP circuit between ignition module and ECA. If continuity is present, check for shorts in PIP circuit and any other circuit. If PIP circuit is okay and no other problem (or codes) is found, replace ECA.

11) SPOUT At Ignition Module Connect test light between ignition module connector VPWR wire and ignition module SPOUT wire. Crank engine. If light comes on or flashes, check ignition SPOUT wire for short to ground. If wire is okay, replace ignition module. If light does not come on, turn ignition off. Leave ignition module connector disconnected.

12) SPOUT Circuit from ECA Check for continuity between breakout box SPOUT test pin and SPOUT terminal at ignition module. If continuity is present, repair short in SPOUT wire and any remaining codes in ECA memory. If problem continues, replace ECA. If continuity is not present, repair SPOUT circuit between ignition module and ECA.

TEST KC - KNOCK SENSOR (KS) & KNOCK CONTROL UNIT (KCU)

Note. Enter this test only when a Code 05 is displayed during SELF-TEST procedure, or when directed here from another CIRCUIT TEST. This test is intended to diagnose only KCU and KS circuits.

Identifying Knock Control Circuit & Connector Terminals. Scheme 87

CIRCUIT PIN IDENTIFICATION

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking KCU Voltage Turn ignition off. Install breakout box, leaving ECA disconnected. Turn ignition on. Measure voltage between test pin No. 24 and ground. Start engine. Tap lightly on engine lifting eye bracket with 4-oz. hammer while varying engine speed between 2500 and 4000 RPM. Voltage should be 3.3-5.0 volts, and should decrease when engine is tapped with hammer. If voltage reading is as specified, test is complete. If voltage is not as specified, go to step 3).

3) Checking KCU Signal Disconnect KCU connector. Attach jumper wires between KS, VPWR and GND terminals of harness connector and KCU. Start engine. Tap lightly on engine lifting eye bracket with 4-oz. hammer while varying engine speed between 2500 and 4000 RPM. Measure voltage between KC terminal of KCU and ground. If voltage is 3.3-5.0 volts and decreases when engine is tapped, repair KC wire between KCU and ECA. If voltage is not as specified, go to step 4).

4) Checking VPWR At KCU Disconnect KCU connector. Turn key on and measure voltage between VPWR terminal of KCU connector and ground. If voltage is greater than 10.0 volts, go to step 5). If voltage is less than 10.0 volts, go to CIRCUIT TEST VPWR.

5) Checking KCU Ground Circuit Disconnect KCU connector. Turn key on and measure voltage between KC wire of KCU connector and ground. If voltage is more than 10.0 volts, go to step 6). If voltage is less than 10.0 volts, repair KCU GND wire.

6) Checking KS Signal Disconnect KCU connector. Set VOM on AC scale. Turn ignition on. Measure AC voltage between KS terminal of KCU connector and ground. Tap lightly on engine lifting eye bracket with 4-oz. hammer. If voltage is more than .03 volt when engine is tapped with hammer, replace KCU. If voltage is not more than .03 volt, go to step 7).

7) Disconnect knock sensor connector. Set VOM on AC scale. Measure AC voltage between KS terminal of knock sensor connector and ground. Tap lightly on engine lifting eye bracket with 4-oz. hammer. If voltage is more than .03 volt when engine is tapped with hammer, repair KS circuit. If voltage is not more than .03 volt, replace knock sensor.

TEST SCG - SOLENOID CONTROLLED BY GROUND

Note. Enter this test only when Code 25, 26, 28, 29, 34, 41 or 42 is displayed during SELF-TEST procedures. This test is intended to diagnose the following switches and circuits: Canister Purge (CANP), EGR Control (EGRC), Fuel Pressure Regulator Control (PRC), High Inlet Air Control (HSIA), Idle Speed Control (ISC) and Turbo Boost Solenoid (BOOST).

Identifying Solenoid Connector Terminals. Scheme 88

CIRCUIT PIN IDENTIFICATION (SCG)

1) Checking System Integrity Visually check all wiring, connectors and components for damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to step 2).

2) Solenoid Function Install breakout box, leaving ECA disconnected. Check function of appropriate solenoid. See SWITCH PERFORMANCE CHECK.

3) If solenoid is okay, test is complete. If solenoid is not okay, remove connector and turn ignition on. Measure voltage between connector VPWR terminal and ground.

4) If voltage is less than 10 volts, repair VPWR circuit. If voltage is more than 10 volts, simulate ECA solenoid activation. See SIMULATED ECA SOLENOID ACTIVATION.

5) Measure voltage between connector VPWR terminal and SIG terminal. If voltage is more than 10 volts only when solenoid is activated, replace solenoid. If voltage is not more than 10 volts when solenoid is activated, disconnect solenoid connector.

6) Check for continuity between breakout box test pin SIG and solenoid SIG terminal. If continuity is not present, repair SIG circuit between solenoid and ECA. If continuity exists, check for continuity between breakout box test pin SIG and all other test pins.

7) If SIG circuit is shorted to any other circuit, repair as necessary. If SIG circuit is not shorted to any other circuit and no other problem or code are found, replace ECA.

SWITCH PERFORMANCE CHECK

To properly diagnose solenoid, it must be checked in the ON and OFF positions. When test procedure requires click test, check appropriate solenoid as follows.

1. BOOST - Install breakout box, leaving ECA disconnected. Turn ignition on. Apply pressure to vacuum nipple of turbocharger boost control solenoid. Using jumper wire, ground test pin No. 31 of breakout box to release vacuum.
2. CANP - Install breakout box, leaving ECA disconnected. Turn ignition on. Apply vacuum to vacuum nipple of canister purge solenoid. Using jumper wire, ground test pin No. 31 of breakout box to release vacuum.
3. EGRC/EGRV - Install breakout box, leaving ECA disconnected. Turn ignition on. Apply vacuum to EGR valve. Vacuum should not hold. Using jumper wire, ground test pin No. 33 of breakout box. Apply vacuum to EGR valve. Vacuum should hold.
4. HSIA - Install breakout box, leaving ECA disconnected. Turn ignition on. Apply vacuum to HSIA solenoid. Vacuum should hold. Using jumper wire, ground test pin No. 53 of breakout box. Vacuum should hold.
5. PRC - Install breakout box, leaving ECA disconnected. Turn ignition on. Apply vacuum to PRC solenoid. Vacuum should hold. Using jumper wire, ground appropriate test pin of breakout box. See «CIRCUIT PIN IDENTIFICATION (SCG)»(/ford/escort/v-1990-1992/remont/testing-diagnostics/#engine-controls-tests-wcodes-eec) . Apply vacuum to PRC solenoid. Vacuum should release.
6. ISC - Install breakout box, leaving ECA disconnected. Turn ignition on. Using jumper wire, ground test pin No. 41 of breakout box. ISC solenoid should click when test pin is grounded.

SIMULATED ECA SOLENOID ACTIVATION

To further diagnose solenoid, ensure ECA and related circuits are capable of operating solenoid. When test procedure requires simulated ECA solenoid activation, check function of appropriate solenoid. Solenoid should function as follows.

1. BOOST - Sudden increase in engine speed to greater than 4500 RPM should activate solenoid.
2. CANP - With engine at normal temperature, solenoid should activate during vehicle cruise or acceleration.
3. EGRC/EGRV - EGRC solenoid should activate at vehicle cruise. EGRV solenoid should activate at wide open throttle.
4. HSIA - Solenoid should activate when engine speed is less than 5000 RPM.
5. ISC - Solenoid should activate during engine cranking and running.
6. PRC - With engine at normal temperature, solenoid should activate during engine cranking, and should remain activated for one minute after engine is started.

TEST STG - SWITCH TO GROUND

Note. Enter this test only when directed here by SWITCH MONITOR TEST. This test is intended to diagnose the following switches and circuits: A/C Switch (ACS), Blower Motor Switch (BLMT), Clutch Engage Switch/Neutral Gear Switch (CES/NGS), Idle Switch (IDL), Power Steering Pressure Switch (PSPS) and Wide Open Throttle Switch (WOT).

Identifying Switch Circuits & Connector Terminals. Scheme 89

CIRCUIT PIN IDENTIFICATION

1) Checking System Integrity Visually check all wiring, connectors and components for damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking Switch Signal Install breakout box. leaving ECA disconnected. Turn ignition off. Measure resistance between component being tested and ground. See CIRCUIT PIN IDENTIFICATION (STG) . Check component resistance in ON and OFF positions. See SWITCH PERFORMANCE CHECK.

3) Resistance should switch from 0-5 ohms (switch closed) to greater than 10,000 ohms (switch open). If resistance is as specified, go to step 6). If resistance is not as specified, disconnect switch. Ensure ignition is off. On all except 2-pin switches, measure component resistance, between switch terminal to ECA and ground, in ON and OFF positions.

4) On 2-pin switches, measure resistance, between component terminals, in ON and OFF positions. On all switches, resistance should switch from 0-5 ohms (switch closed) to greater than 10,000 ohms (switch open). If resistance is as specified, go to step 5). If resistance is not as specified, replace switch.

5) Circuit Check Ensure ignition is off and switch is disconnected. Measure resistance between test pin of component breakout box and test pins No. 26, 37, 57 and 60. Resistances should all be more than 10,000 ohms. If resistance is not as specified, repair circuit(s).

6) If all circuits are okay, measure resistance between test pin of component breakout box and switch connector. If resistance is less than 5 ohms and no other problem or code are found, replace ECA. If resistance is more than 5 ohms, repair circuit.

Switch must be checked in ON and OFF positions. Switch should function as follows

1. ACS - Switch is closed when A/C button is on and blower is operating.
2. BLMT - Switch is closed in every position except OFF.
3. CES/NGS - CES switch is closed when clutch pedal is up. NGS switch is closed when transaxle is in Neutral.
4. IDL - Switch is open when throttle is depressed.
5. PSPS - PSPS switch is open when system pressure is less than approximately 245 psi (16.9 kg/cm 2 ). Switch is closed when system pressure is approximately greater than 290 psi (20.0 kg/cm 2 ).
6. WOT - Switch is closed when throttle is open.

TEST STI - SELF-TEST INPUT

Note. Enter this test only when SUPER STAR II tester displays STO LO, or VOM displays zero volt.

CIRCUIT PIN IDENTIFICATION (STI)

CHECKING SYSTEM INTEGRITY

Visually check all wiring and connectors for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to SYSTEM VOLTAGE CHECK.

SYSTEM VOLTAGE CHECK

Install breakout box and leave ECA disconnected. Connect test light between STI test pin and 12-volt source. With STI diagnostic connector grounded, light should be on. (Scheme 76)and (Scheme 77). With STI diagnostic connector not grounded, light should be off. If STI test as specified, go to CIRCUIT TEST STO. If STI does not test as specified, repair circuit between STI connector and ECA.

TEST STO - SELF-TEST OUTPUT

Note. Enter this test only when codes cannot be retrieved, or when instructed by CIRCUIT TEST STI.

Identifying STO Connector Terminals. Scheme 90

CIRCUIT PIN IDENTIFICATION

1) Checking System Integrity Visually check all wiring and connectors for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to step 2).

2) Install breakout box and leave ECA disconnected. Check for continuity between STO test pin and STO diagnostic connector terminal. If continuity is not present, repair circuit between ECA and STO diagnostic connector. If continuity is present, go to step 3).

3) Check for continuity between STO test pin and all other test pins. If continuity is present between STO test pin and other test pin(s), circuit is shorted. Repair as necessary. If continuity is not present, return to TESTS W/O CODES article.

TEST STP - SWITCH TO POWER

Note. Enter this test only when directed here from SWITCH MONITOR TEST. This test is intended to diagnose the following switches and circuits: Brake On-Off Switch (BOO), Cooling Fan Relay (FAN), Headlight Switch (HLDT), Rear Window Defrost (DEF) and Vehicle Start Switch (VST).

Identifying Switch Circuit & Connector Terminals. Scheme 91

CIRCUIT PIN IDENTIFICATION

1) Checking System Integrity Visually check all wiring, connectors and components for damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking Switch Signal Install breakout box, leaving ECA disconnected. Turn ignition on. Measure voltage between breakout box test pin of component being tested and ground. See CIRCUIT PIN IDENTIFICATION (STP) . Check voltage with component in ON and OFF positions. See SWITCH PERFORMANCE CHECK.

3) Voltage should switch from 0-4 volts to 10-14 volts. If voltage is as specified and no other problem or code are found, replace ECA. If voltage is not as specified, measure voltage at switch connector terminal. Check voltage with component in ON and OFF positions.

4) If voltage switches from 0-4 volts to 10-14 volts, repair open circuit between switch and ECA. If voltage does not switch from 0-4 volts to 10-14 volts, turn ignition off. Measure resistance between test pin of component breakout box and test pins No. 26, 37, 57 and ground. Resistances should all be more than 10,000 ohms. If resistance is not as specified, repair circuit(s).

5) If all circuits are okay, measure resistance between test pin of component breakout box and switch connector. Resistance should be less than 5 ohms with switch closed, and more than 10,000 ohms with switch open. If resistance is not as specified, replace switch. If resistance is as specified and no other problem or code are found, replace ECA.

Switch must be checked in ON and OFF positions. Switch should perform as follows

1. BOO - Switch is closed when brake pedal is applied.
2. FAN - Switch is closed by grounding coolant temperature switch.
3. DEF - Switch is closed by turning rear defroster on.
4. HLDT - Switch is closed by turning headlights on.
5. VST - Switch is closed when engine is cranking.

TEST TP - THROTTLE POSITION SENSOR

Note. To diagnose throttle position on 1.8L with manual transaxle, see CIRCUIT TEST STG. Enter this test only when a Code 12 is displayed during SELF-TEST procedure, or when directed here from another CIRCUIT TEST. To prevent replacement of good components, check the following non-EEC components for fault: idle speed or throttle stop adjustments, throttle shaft or linkage, and cruise control linkage.

Identifying TP Connector Terminals. Scheme 92

CIRCUIT PIN IDENTIFICATION

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking TPS Voltage Ensure engine is at operating temperature. With ignition off, install breakout box. Turn ignition on. Measure voltage between TPS and SIGRTN test pins. Slowly depress accelerator pedal and compare voltage to specifications shown in VOLTAGE & RESISTANCE SPECIFICATIONS (TP SENSOR) . If voltage is within specification, TPS circuit is okay; fault is in another circuit or ECA. If voltage is not within specification, go to step 4).

3) Checking TPS Signal Return Remove TPS connector. Using jumper wire, attach SIGRTN and VREF connector terminals to TPS sensor. Attach voltmeter between sensor TPS terminal and SIGRTN terminal. Turn ignition on. Slowly depress accelerator pedal and compare voltage to specifications shown in VOLTAGE & RESISTANCE SPECIFICATIONS (TP SENSOR) . If voltage is as specified, repair TPS circuit between ECA and TPS. If voltage is not as specified, go to step 4).

4) Checking SIGRTN/VREF At TPS Remove TPS connector. Turn ignition on. Measure voltage between TPS wire and SIGRTN wire. If voltage is 4.5-5.5 volts, adjust or replace TPS. If voltage is not 4.5-5.5 volts, go to CIRCUIT TEST VREF.

VOLTAGE & RESISTANCE SPECIFICATIONS (1)

TEST VAF - VANE AIRFLOW METER

Note. Enter this test only when a Code 08 is displayed during SELF-TEST procedure, or when directed here from another CIRCUIT TEST. To avoid unnecessary use of diagnostic time, check for unmetered air leaks between VAF meter and throttle body. This test is intended to diagnose only VAF and VMREF circuits.

Identifying VAF Meter Connector Terminals. Scheme 93

CIRCUIT PIN IDENTIFICATION

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking VAF Meter Voltage Install breakout box. Turn ignition on. Measure voltage between VAF and SIGRTN test pins while moving air door. Voltage should be as listed in VOLTAGE SPECIFICATIONS (VAF METER) . If voltage is not as specified, go to step 4). On 1.8L engines, if voltage is as specified, VAF meter and circuit are okay. Fault is in another circuit or in ECA.

3) On 2.2L engines, if voltage is as specified, measure voltage between VMREF and SIGRTN test pins. If voltage is 7-9 volts, VAF and circuit are okay; fault is in another circuit or ECA. If voltage is not 7-9 volts, repair VMREF circuit between ECA and VAF meter.

VOLTAGE SPECIFICATIONS

4) Checking Signal From VAF Meter Locate VAF meter measuring vane and remove connector. On 1.8L engines, jumper SIGRTN and VREF connector terminals to matching terminals on VAF meter. On 2.2L engines, jumper SIGRTN, VMREF and VPWR connector terminals to matching terminals on VAF meter. Leave VAF circuit open. Turn ignition on. Measure voltage between VAF terminal at meter and SIGRTN terminal at harness connector while moving air door. Voltage should be as listed in VOLTAGE SPECIFICATIONS (VAF METER) . On 1.8L engines, if voltage is not as specified, go to next step. On 2.2L engines, If voltage is as specified, go to step 6). On all models, if voltage is as specified repair VAF circuit between ECA and VAF meter.

5) Checking VREF At VAF Meter Turn ignition off. Remove VAF meter connector. Turn ignition on. Measure voltage between VAF wire and SIGRTN wire. If voltage is 4.5-5.5 volts, replace VAF meter. If voltage is not 4.5-5.5 volts, go to CIRCUIT TEST VREF.

6) VAF Signal Without VMREF Locate air door of VAF meter. Turn ignition off. Remove meter connector. Using jumper wire, attach SIGRTN and VPWR connector terminals to matching terminals of VAF meter. Leave VAF and VMREF circuits open. Turn ignition on. Measure voltage between VAF terminal and SIGRTN terminal on VAF meter. As flap is moved, voltage should be as listed in VOLTAGE SPECIFICATIONS (VAF METER) . If voltage is as specified, repair VMREF circuit between ECA and VAF meter. If voltage is not as specified, go to step 7).

7) SIGRTN/VPWR At VAF Meter Remove VAF meter connector. Turn ignition on. Measure voltage between VPWR terminal and SIGRTN terminal at connector. If voltage is greater than 10 volts, replace VAF meter. If voltage is less than 10 volts, measure voltage between VPWR terminal and ground. If voltage is more than 10 volts, repair SIGRTN wire between VAF meter and ECA. If voltage is less than 10 volts, go to CIRCUIT TEST VPWR.

TEST VAT - VANE AIR TEMPERATURE

Note. Enter this test only when a Code 10 is displayed during SELF-TEST procedure, or when directed here from another CIRCUIT TEST. Ambient temperature must be greater than 50°F (10°C) for this test.

Identifying VAT Sensor Circuit & Connector Terminals. Scheme 94

CIRCUIT PIN IDENTIFICATION

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking VAT Voltage Ensure engine is at operating temperature. With ignition off, install breakout box. Locate VAT sensor in Vane Airflow (VAF) meter. Turn ignition on. Measure voltage between VAT and SIGRTN test pins. Compare voltage to specifications shown in VOLTAGE SPECIFICATIONS (VAT SENSOR) . If voltage is within specification, VAT circuit is okay; fault is in another circuit or ECA. If voltage is not within specification, go to step 3).

Note. If using hot air gun to heat sensor, avoid overheating plastic or rubber components.

VOLTAGE SPECIFICATIONS

3) Checking VAT Resistance Ensure engine is at operating temperature. With ignition off and breakout box installed, measure resistance between VAT and SIGRTN test pins. Compare resistance to specifications shown in RESISTANCE SPECIFICATIONS (VAT SENSOR) . If resistance is within specification, go to step 4). If resistance is not as specified, go to step 5).

RESISTANCE SPECIFICATIONS

4) VAT Circuit Isolation With breakout box installed, leave ECA disconnected. Remove VAF meter connector. Measure resistance between VAT and all other test pins. If any resistance is less than 5 ohms, repair VAT sensor circuit to VAF meter. If resistance is more than 5 ohms, replace ECA.

5) VAT Sensor Resistance Disconnect VAF meter connector. Locate VAT sensor in VAF meter. With ignition off, measure resistance between VAT terminal and SIGRTN terminal of VAF meter. Compare resistance to specifications shown in RESISTANCE SPECIFICATIONS (VAT SENSOR) . If resistance is okay, repair VAT and/or SIGRTN circuit between VAF meter and ECA. If resistance is not as specified, replace VAF meter.

TEST VSS - VEHICLE SPEED SENSOR

Note. Enter this test only when Code 06 is displayed during SELF-TEST procedures. This test is intended to diagnose only vehicle speed sensor circuits.

Identifying Vehicle Speed Sensor Connector Terminals. Scheme 95

CIRCUIT PIN IDENTIFICATION

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to step 2).

2) Checking VSS Input Signal With ignition off, install breakout box and leave ECA disconnected. If VSS is located on speedometer drive gear, remove drive gear from transaxle, leaving wiring harness connected. If VSS is located on instrument cluster, disconnect speedometer cable from transaxle. Measure continuity between VSS and GND test pins. Rotate speedometer cable or drive gear.

3) Continuity should exist 4 times per speedometer cable revolution on 2.2L engines, or 8 times per revolution on 1.8L engines. If continuity is as specified, VSS circuit is okay. Replace ECA. On 2.2L engines with analog instrument cluster, if continuity is not as specified, go to step 4). On all other models, if continuity is not as specified, go to step 7).

4) Disconnect instrument cluster. Remove VSS connector at instrument cluster. With speedometer cable disconnected from transaxle, rotate speedometer cable. Measure continuity between speed sensor VSS terminal and GND terminal. Continuity should exist 4 times per speedometer cable revolution.

5) If continuity is as specified and speedometer is working, repair VSS or GND circuit between VSS sensor and ECA or transmission module (if equipped). If continuity is as specified and speedometer is NOT working, check speedometer drive gear. If drive gear is okay, repair VSS or GND circuit between VSS sensor and ECA.

6) If continuity is NOT as specified and speedometer is working, replace speedometer head and/or printed circuit board. If continuity is NOT as specified and speedometer is NOT working, check speedometer cable. If cable is okay, replace speedometer head and/or printed circuit board.

7) Disconnect VSS connector at transaxle. Remove VSS from transaxle. Rotate speedometer drive gear and measure continuity between VSS and GND terminals of VSS. Continuity should exist 4 times per speedometer drive gear revolution on 2.2L engines with digital instrument cluster, or 8 times per revolution on 1.8L engines.

8) On 1.8L Engines, if continuity is as specified, repair VSS or GND circuit. If continuity is not as specified, replace vehicle speed sensor or speedometer drive gear.

9) On 2.2L engines, if continuity is as specified and speedometer is working, repair VSS or GND circuit. If continuity is as specified and speedometer is NOT working, check speedometer drive gear; if drive gear is okay, repair VSS or GND circuit. If continuity is NOT as specified and speedometer is working, replace instrument cluster. If continuity is NOT as specified and speedometer is NOT working, check wiring to instrument cluster; if wiring is okay, replace instrument cluster.

TEST VPWR - VEHICLE POWER

Note. Enter this test only when directed here from CIRCUIT TESTS. To prevent replacement of good components, check for faults in the following non-EEC components: ignition switch, alternator, battery cables, ground straps or voltage regulator. This test is intended to diagnose only the following circuits: VPWR and GND.

Identifying VPWR Circuit & Connector Terminals. Scheme 96

CIRCUIT PIN IDENTIFICATION

1) Checking Circuit Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, check battery voltage and charge condition. Service as necessary and go to step 2).

2) Ground Circuit Check Turn ignition off and install breakout box. Turn ignition on. Measure voltage between the followings points.

1. VPWR test pin and battery ground
2. VPWR test pin and each ground test pin
3. VPWR test pin and each ECA ground wire

If all voltages are greater than 10 volts, go to CIRCUIT TEST VREF. If all voltages are less than 10 volts, repair as necessary.

3) VPWR From Main Relay Turn ignition off. Locate main power relay inside rectangular cover behind master cylinder reservoir. Disconnect main power relay 4-wire connector. Using jumper wire, attach BATT, PWR, and GND terminals to matching terminals in connector. Leave VPWR circuit disconnected.

4) Turn ignition on. Measure voltage between main power relay connector VPWR terminal and ground. If voltage is more than 10 volts, repair VPWR circuit between main power relay and ECA. If voltage is less than 10 volts, measure voltage between main power relay connector BATT terminal and ground.

5) If voltage is less than 10 volts, repair BATT circuit between main power relay and battery. If voltage is more than 10 volts, measure voltage between main power relay connector PWR terminal and ground. If voltage is less than 10 volts, repair PWR circuit between main power relay and ignition switch.

6) If voltage is more than 10 volts, measure voltage between main power relay connector BATT terminal and GND terminal. If voltage is less than 10 volts, repair main power relay ground wire. If voltage is not less than 10 volts, ground circuit is okay. Replace main power relay.

TEST VREF - REFERENCE VOLTAGE & SIGNAL RETURN

Note. Perform this test when a check for VREF has failed in the sensor input CIRCUIT TEST. This test is intended to diagnose only the following circuits: VREF and SIGRTN.

Identifying VREF Connector Terminals. Scheme 97

CIRCUIT PIN IDENTIFICATION

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If fault is found, repair as necessary. If no fault is found, go to step 2).

2) Voltage Check Disconnect Throttle Position Sensor (TPS) connector. Turn ignition on. Check voltage between VREF and SIGRTN wires of TPS connector. If voltage is 4-5 volts, circuit is okay. If voltage is 10-12 volts, repair short to battery.

3) Turn ignition off. Disconnect transmission module (if equipped). Install breakout box. Turn ignition on. On 1.8L engines, measure voltage between VAF Green/Red wire and Black/Brown wire. On 2.2L engines, measure voltage between TPS Green/Red wire and Green/Yellow wire. If voltage is 4-5 volts, circuit is okay. If voltage is 10-12 volts, repair short to battery.

4) Circuit Resistance Check Turn ignition off. Locate 4EAT module under instrument panel, near steering column. Install 4EAT Tester (007-00037), leaving module disconnected. Measure resistance between ECA and 4EAT module of the following circuits; VREF, TPS, EVP and VAF. If any resistance is greater than 5 ohms, repair circuits as necessary.

5) If all resistances in step 4) are less than 5 ohms, disconnect EVP, TPS and VAF connectors. Measure resistance between VREF breakout box pin and ground. If resistance is less than 10,000 ohms, repair short in VREF circuit. If resistance is greater than 10,000 ohms, remove ECT, EVP, TPS and VAF connectors.

6) Measure resistance between all SIGRTN terminal connectors. Repair any circuit with resistance greater than 5 ohms. If resistance of circuit is less than 5 ohms, measure voltage at ECA SIGRTN connector terminal. If voltage is more than one volt, repair short circuit to battery. If less than one volt is present, turn ignition off.

7) Measure resistance between breakout box test pin No. 6 (1.8L) or No. 5 (2.2L) and ground. If resistance is less than 5 ohms, measure resistance between ground and the following test pins: No. 39, 40, 44, and 60. If resistance of any circuit is more than 5 ohms, repair as necessary. If resistance is less than 5 ohms and no other code or fault are present, replace ECA.

See also:
• SELF-TEST PROCEDURES
• SWITCH MONITOR TEST
• CODE REFERENCE CHART
• CLEARING CODES