13 TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM DTC DTC DTC P0136 P0137 P0138 Oxygen Sensor Circuit Malfunction (ank 1 Sensor ) Heated Oxygen Sensor Circuit Low Voltage (ank 1 Sensor ) Oxygen Sensor Circuit High Voltage (ank 1 Sensor ) Sensor refers to the sensor mounted behind the Three-Way Catalytic Converter (TWC) and located far from the engine assembly. DCRIPTION In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC is used. For the most efficient use of the TWC, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel level. For the purpose of helping the ECM to deliver accurate air-fuel ratio control, a Heated Oxygen (HO) sensor is used. The HO sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low). When the air-fuel ratio becomes lean, the oxygen concentration in the exhaust gas is rich. The HO sensor informs the ECM that the post-twc air-fuel ratio is lean (low voltage, i.e. less than 0.45 V). Conversely, when the air-fuel ratio is richer than the stoichiometric air-fuel level, the oxygen concentration in the exhaust gas becomes lean. The HO sensor informs the ECM that the post-twc air-fuel ratio is rich (high voltage, i.e. more than 0.45 V). The HO sensor has the property of changing its output voltage drastically when the air-fuel ratio is close to the stoichiometric level. The ECM uses the supplementary information from the HO sensor to determine whether the air-fuel ratio after the TWC is rich or lean, and adjusts the fuel injection time accordingly. Thus, if the HO sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air-fuel ratio control.
TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM 133 tmosphere ir Housing Platinum Electrode Ideal ir Fuel Mixture Solid Electrolyte (Zirconia Element) Heater Cover Coating (Ceramic) Richer - ir Fuel Ratio - Leaner Exhaust Gas 115539E0 DTC No. DTC Detection Conditions Trouble reas P0136 P0137 P0138 bnormal voltage output (active air-fuel ratio control): During active air-fuel ratio control, following conditions (a) and (b) met for certain period of time (1 trip detection logic): (a) Heated Oxygen (HO) sensor voltage does not decrease to less than 0.1 V (b) HO sensor voltage does not increase to more than 0.59 V Low impedance: Sensor impedance less than 5 Ωfor more than 30 seconds when ECM presumes sensor to being warmed up and operating normally (1 trip detection logic) Low voltage (open): During active air-fuel ratio control, following conditions (a) and (b) met for certain period of time (1 trip detection logic): (a) HO sensor voltage output less than 0.1 V (b) Target air-fuel ratio rich High impedance: Sensor impedance 15 kω or more for more than 90 seconds when ECM presumes sensor to being warmed up and operating normally (1 trip detection logic) High voltage (short): During active air-fuel ratio control, following conditions (a) and (b) met for certain period of time (1 trip detection logic): (a) HO sensor voltage output less than 0.59 V or more (b) Target air-fuel ratio lean Extremely high voltage (short) : HO sensor voltage output exceeds 1. V for more than 10 seconds (1 trip detection logic) Open or short in HO sensor (sensor ) circuit HO sensor (sensor ) HO sensor heater (sensor ) ir-fuel Ratio (/F) sensor (sensor 1) EFI relay Gas leakage from exhaust system Open in HO sensor (sensor ) circuit HO sensor (sensor ) HO sensor (sensor ) heater EFI relay Gas leakage from exhaust system Short in HO sensor (sensor ) circuit HO sensor (sensor ) ECM internal circuit malfunction MONITOR DCRIPTION ctive ir-fuel Ratio Control
134 TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM The ECM usually performs air-fuel ratio feedback control so that the ir-fuel Ratio (/F) sensor output indicates a near stoichiometric air-fuel level. This vehicle includes active air-fuel ratio control in addition to regular air-fuel ratio control. The ECM performs active air-fuel ratio control to detect any deterioration in the Three-Way Catalytic Converter (TWC) and Heated Oxygen (HO) sensor malfunctions (refer to the diagram below). ctive air-fuel ratio control is performed for approximately 15 to 0 seconds while driving with a warm engine. During active air-fuel ratio control, the air-fuel ratio is forcibly regulated to become lean or rich by the ECM. If the ECM detects a malfunction, one of the following DTCs is set: DTC P0136 (abnormal voltage output), P0137 (open circuit) and P0138 (short circuit). bnormal Voltage Output of HO Sensor (DTC P0136) While the ECM is performing active air-fuel ratio control, the air-fuel ratio is forcibly regulated to become rich or lean. If the sensor is not functioning properly, the voltage output variation is small. For example, when the HO sensor voltage does not decrease to less than 0.1 V and does not increase to more than 0.59 V during active air-fuel ratio control, the ECM determines that the sensor voltage output is abnormal and sets DTC P0136. HO SENSOR CIRCUIT MLFUNCTION (P0136: NORML VOLTGE) 15 to 0 seconds Operation ctive air fuel ratio control Off Normal 0.59 V HO sensor voltage bnormal 0.1 V 115540E03 Open or Short in Heated Oxygen (HO) Sensor Circuit (DTC P0137 or P0138) During active air-fuel ratio control, the ECM calculates the Oxygen Storage Capacity (OSC) * of the Three- Way Catalytic Converter (TWC) by forcibly regulating the air-fuel ratio to become rich or lean. If the HO sensor has an open or short, or the voltage output of the sensor noticeably decreases, the OSC indicates an extraordinarily high value. Even if the ECM attempts to continue regulating the airfuel ratio to become rich or lean, the HO sensor output does not change. While performing active air-fuel ratio control, when the target air-fuel ratio is rich and the HO sensor voltage output is 0.1 V or less (lean), the ECM interprets this as an abnormally low sensor output voltage and sets DTC P0137. When the target air-fuel ratio is lean and the voltage output is 0.59 V or more (rich) during active air-fuel ratio control, the ECM determines that the sensor voltage output is abnormally high, and sets DTC P0138. DTC P0138 is also set if the HO sensor voltage output is more than 1. V for 10 seconds or more.
TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM 135 * : The TWC has the capability to store oxygen. The OSC and the emission purification capacity of the TWC are mutually related. The ECM determines whether the catalyst has deteriorated, based on the calculated OSC value (see page -06). HO SENSOR CIRCUIT LOW VOLTGE (P0137: OPEN) 15 to 0 seconds Operation ctive air fuel ratio control Target air fuel ratio Off Stoichiometric ir Fuel Level Normal Rich bnormal Normal HO sensor voltage 0.1 V bnormal HO SENSOR CIRCUIT HIGH VOLTGE (P0138: SHORT) Operation ctive air fuel ratio control Off Lean Target air fuel ratio Stoichiometric ir Fuel Level bnormal HO sensor voltage 0.59 V 115541E03 High or Low Impedance of Heated Oxygen (HO) Sensor (DTC P0136 or P0137)
136 TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM Relationship between element temperature and impedance: (Ω) 15,000 DTC Detection rea 1,000 100 10 5 300 400 500 600 700 800 (57) (75)(93)(1,11)(1,9)(1,47) C ( F) 076841E04 During normal air-fuel ratio feedback control, there are small variations in the exhaust gas oxygen concentration. In order to continuously monitor the slight variation of the HO sensor signal while the engine is running, the impedance* of the sensor is measured by the ECM. The ECM determines that there is a malfunction in the sensor when the measured impedance deviates from the standard range. * : The effective resistance in an alternating current electrical circuit. The impedance cannot be measured using an ohmmeter. DTC P0136 indicates the deterioration of the HO sensor. The ECM sets the DTC by calculating the impedance of the sensor when the typical enabling conditions are satisfied (1 driving cycle). DTC P0137 indicates an open or short circuit in the HO sensor (1 driving cycle). The ECM sets the DTC when the impedance of the sensor exceeds the threshold 15 kω. MONITOR STRTEGY Related DTCs Required Sensors/Components (Main) Required Sensors/Components (Related) Frequency of Operation Duration MIL Operation Sequence of Operation P0136: Heated oxygen sensor output voltage (Output voltage) P0136: Heated oxygen sensor impedance (Low) P0137: Heated oxygen sensor output voltage (Low voltage) P0137: Heated oxygen sensor impedance (High) P0138: Heated oxygen sensor output voltage (High voltage) P0138: Heated oxygen sensor output voltage (Extremely high) Heated oxygen sensor Crankshaft position sensor, engine coolant temperature sensor, mass air flow meter and throttle position sensor Once per driving cycle: ctive air-fuel ratio control detection Continuous: Others 90 seconds: Heated oxygen sensor impedance (High) Within 0 seconds: ctive air-fuel ratio control detection 30 seconds: Heated oxygen sensor impedance (Low) 10 seconds: Output voltage (High stuck) Immediate None
TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM 137 TYPICL ENLING CONDITIONS ll: Monitor runs whenever following DTCs not present P0031, P003, P0051, P005 (/F sensor heater - Sensor 1) P0037, P0038, P0057, P0058 (O sensor heater - Sensor ) P0100 - P0103 (MF meter) P0110 - P0113 (IT sensor) P0115 - P0118 (ECT sensor) P010 - P03, P135 (TP sensor) P015 (Insufficient ECT for closed loop) P0171, P017 (Fuel system) P0300 - P0308 (Misfire) P0335 (CKP sensor) P0340, P0341 (CMP sensor) P044 - P0456 (EVP system) P0500 (VSS) P196, P198 (/F sensor - rationality) P440 (/R control valve stuck open) P441 (/R control valve stuck close) P444 (IP stuck ON) P445 (IP stuck OFF) P00, P03 (/F sensor - slow response) Heated Oxygen Sensor (, High Voltage and Low Voltage): ctive air-fuel ratio control Executing ctive air-fuel ratio control begins when all of following conditions met: - attery voltage 11 V or more Engine coolant temperature 70 C (158 F) or more Idling OFF Engine RPM Less than 4,000 rpm /F sensor status ctivated Fuel cut OFF (for 5 seconds or more) Engine load 10 to 80 % Shift position 4th or 5th (for M/T) 3rd, 4th or 5th (for /T) Heated Oxygen Sensor Impedance (Low): attery voltage Estimated sensor temperature DTC P0606 Heated Oxygen Sensor Impedance (High): attery voltage Estimated sensor temperature DTC P0606 11 V or more Less than 700 C(1,9 F) Not set 11 V or more More than 450 C(84 F) Not set Heated Oxygen Sensor (Extremely High): attery voltage 11 V or more Time after engine start seconds or more TYPICL MLFUNCTION THRHOLDS Heated Oxygen Sensor (Output voltage): Either of following conditions met: 1 or 1. ll of the following conditions (a), (b) and (c) met - (a) Commanded air-fuel ratio 14.3 or less (b) Rear HO sensor voltage 0.1 to 0.59 V (c) OSC (Oxygen Storage Capacity of Catalyst).5 g or more. ll of the following conditions (d), (e) and (f) met -
138 TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM (d) Commanded air-fuel ratio (e) Rear HO sensor voltage (f) OSC (Oxygen Storage Capacity of Catalyst) 14.9 or more 0.1 to 0.59 V.5 g or more Heated Oxygen Sensor (Low output voltage): ll of the following conditions (a), (b) and (c) met - (a) Commanded air-fuel ratio 14.3 or less (b) Rear HO sensor voltage Less than 0.1 V (c) OSC (Oxygen Storage Capacity of Catalyst).5 g or more Heated Oxygen Sensor (High output voltage): ll of the following conditions (a), (b) and (c) met - (a) Commanded air-fuel ratio 14.9 or more (b) Rear HO sensor voltage More than 0.59 V (c) OSC (Oxygen Storage Capacity of Catalyst).5 g or more Heated Oxygen Sensor Impedance (Low): Duration of following condition met 30 seconds or more Heated oxygen sensor impedance Less than 5 Ω Heated Oxygen Sensor Impedance (High): Duration of following condition met Heated oxygen sensor impedance 90 seconds or more 15 kω or more Heated Oxygen Sensor Impedance (Extremely High): Duration of following condition met 10 seconds or more Heated oxygen sensor impedance 1. V or more COMPONENT OPERTING RNGE Duration of following condition met Heated oxygen sensor voltage 30 seconds or more Varies between 0.1 and 0.9 V MONITOR RULT Refer to Checking Monitor Status (See page -1).
TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM 139 WIRING DIGRM Engine Room J/ ECM L-W 14 6 1 EFI No. Engine Room R/ G-W L-W R 4 H3 Heated Oxygen Sensor + E HT1 1 OX1 3 10 I1 (*1) G W G-W (*1) E4 5 E4 8 E8 HT1 OX1 MREL 3 5 1 EFI Relay Engine Room R/ 5 IF1 R 8 E4 E R L W- EFI 30 Engine Room R/ 3 1 J1 J/C 1 1 C 33 R W- *1:Shielded attery E EH 11741E01
140 TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM CONFIRMTION DRIVING PTTERN This confirmation driving pattern is used in the "PERFORM CONFIRMTION DRIVING PTTERN" procedure of the following diagnostic troubleshooting procedure. Performing this confirmation pattern will activate the Heated Oxygen (HO) sensor monitor. (The catalyst monitor is performed simultaneously.) This is very useful for verifying the completion of a repair. Vehicle Speed NOTICE: etween 40 and 70 mph (64 and 113 km/h ) (h) This test will not be completed if the vehicle is driven under absolutely constant speed, such as with cruise control activated. Idling (g) Ignition Switch ON Warm up 10 minutes Time (Note: Even when vehicle stops during pattern, test can be resumed.) 11537E07 11641 (a) Connect an intelligent tester to the DLC3. (b) Turn the ignition switch to ON. (c) Turn the tester or scan tool ON. (d) Clear DTCs (where set) (See page -40). (e) If using an intelligent tester, select the following menu items: DIGNOSIS / CR OD II / REDINS TTS. (f) Check that OS EVL is INCMPL (incomplete). (g) Start the engine and warm it up. (h) Drive the vehicle at between 40 mph and 70 mph (64 km/h and 113 km/h) for at least 10 minutes.
TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM 141 (i) Note the state of the Readiness Tests items. Those items will change to COMPL (complete) as OS EVL monitor operates. (j) On the tester, select the following menu items: DIGNOSIS / ENHNCED OD II / DTC INFO / PENDING COD and check if any DTCs (any pending DTCs) are set. If OS EVL does not change to COMPL, and any pending DTCs fail to set, extend the driving time. Intelligent tester only : Malfunctioning areas can be identified by performing the /F CONTROL function provided in the CTIVE TT. The /F CONTROL function can help to determine whether the ir-fuel Ratio (/F) sensor, Heated Oxygen (HO) sensor and other potential trouble areas are malfunctioning. The following instructions describe how to conduct the /F CONTROL operation using an intelligent tester. (a)connect an intelligent tester to the DLC3. (b)start the engine and turn the tester ON. (c) Warm up the engine at an engine speed of,500 rpm for approximately 90 seconds. (d)on the tester, select the following menu items: DIGNOSIS / ENHNCED OD II / CTIVE TT / / F CONTROL. (e)perform the /F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume). (f) Monitor the voltage outputs of the /F and HO sensors (FS 1S1 and OS 1S) displayed on the tester. The /F CONTROL operation lowers the fuel injection volume by 1.5 % or increases the injection volume by 5 %. Each sensor reacts in accordance with increases and decreases in the fuel injection volume. Standard Voltage Tester Display (Sensor) Injection Volumes Status Voltages FS 1S1 (/F) +5% Rich Less than 3.0 FS 1S1 (/F) -1.5% Lean More than 3.35 OS 1S +5% Rich More than 0.5 OS 1S -1.5% Lean Less than 0.4 NOTICE: The ir-fuel Ratio (/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO) sensor has a maximum output delay of approximately 0 seconds. Case /F Sensor (Sensor 1) HO Sensor (Sensor ) Main Suspected Trouble rea Injection Volume +5 % -1.5 % Injection Volume +5 % -1.5 % 1 More than 3.35 V Less than 3.0 V More than 0.55 V Less than 0.4 V - Injection Volume +5 % -1.5 % lmost no reaction Injection Volume +5 % -1.5 % More than 0.55 V Less than 0.4 V /F sensor /F sensor heater /F sensor circuit
14 TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM Case /F Sensor (Sensor 1) HO Sensor (Sensor ) Main Suspected Trouble rea 3 Injection Volume +5 % -1.5 % More than 3.35 V Less than 3.0 V Injection Volume +5 % -1.5 % lmost no reaction HO sensor HO sensor heater HO sensor circuit 4 Injection volume +5 % -1.5 % lmost no reaction Following the /F CONTROL procedure enables technicians to check and graph the voltage outputs of Injection Volume +5 % -1.5 % lmost no reaction Fuel injector Fuel pressure Gas leakage from exhaust system (ir fuel ratio extremely lean or rich) both the /F and HO sensors. To display the graph, select the following menu items on the tester: DIGNOSIS / ENHNCED OD II / CTIVE TT / /F CONTROL / USER DT / FS 1S1 and OS 1S, and press the Y button and then the ENTER button followed by the F4 button. If other DTCs relating to different systems that have terminal E as the ground terminal are output simultaneously, terminal E may have an open circuit. Read freeze frame data using an intelligent tester. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred. If the OX1 wire from the ECM connector is short-circuited to the + wire, DTC P0136 will be set. 1 RED OUTPUT DTC (a) Connect an intelligent tester to the DLC3. (b) Turn the ignition switch to ON and turn the tester ON. (c) Select the following menu items: DIGNOSIS / ENHNCED OD II / DTC INFO / CURRENT COD. (d) Read DTCs. Result Display (DTC output) P0138 P0137 P0136 Proceed to C C Go to step 14 Go to step 7 RED DT LIST (OUTPUT VOLTGE OF HETED OXYGEN SENSOR) (a) (b) Connect the intelligent tester to the DLC3. Turn the ignition switch to ON and turn the tester ON.
TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM 143 (c) Select the following menu items: DIGNOSIS / ENHNCED OD II / DT LIST / PRIMRY / OS 1S. (d) (e) llow the engine to idle. Read the Heated Oxygen (HO) sensor output voltage while idling. Result HO Sensor s More than 1. V Less than 1.0 V Proceed to Go to step 5 3 CHECK HRNS ND CONNECTOR (CHECK FOR SHORT) E4 ECM Connector (a) (b) (c) Turn the ignition switch to OFF and wait for 5 minutes. Disconnect the E4 ECM connector. Check the resistance. Standard Resistance Tester Connection HT1 (E4-) - OX1 (E4-5) Specified Condition 10 kω or higher OX1 HT1 065743E66 (d) Reconnect the ECM connector. OK REPLCE ECM NG 4 INSPECT HETED OXYGEN SENSOR (CHECK FOR SHORT) Component Side: HO Sensor H3 Sensor + HT1 E OX1 Front View 058685E04 (a) (b) (c) NG Disconnect the H3 HO sensor connector. Check the resistance. Standard Resistance Tester Connections Specified Conditions + (H3-) - E (H3-4) 10 kω or higher + (H3-) - OX1 (H3-3) 10 kω or higher Reconnect the HO sensor connector. REPLCE HETED OXYGEN SENSOR OK REPIR OR REPLCE HRNS OR CONNECTOR
144 TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM 5 PERFORM CONFIRMTION DRIVING PTTERN NEXT 6 CHECK WHETHER DTC OUTPUT RECURS (DTC P0138) (a) (b) On the intelligent tester, select the following menu items: DIGNOSIS / ENHNCED OD II / DTC INFO / CURRENT COD. Read DTCs. Result Display (DTC Output) P0138 No output Proceed To CHECK FOR INTERMITTENT PROLEMS REPLCE HETED OXYGEN SENSOR 7 RED DT LIST (OUTPUT VOLTGE OF HETED OXYGEN SENSOR) (a) Connect the intelligent tester to the DLC3. (b) Turn the ignition switch to ON and turn the tester ON. (c) Start the engine. (d) Select the following menu items: DIGNOSIS / ENHNCED OD II / DT LIST / LL / OS 1S (e) fter warming up the engine, run the engine at an engine speed of,500 rpm for 3 minutes. (f) Read the output voltage of the HO sensor when the engine rpm is suddenly increased. Quickly accelerate the engine to 4,000 rpm 3 times using the accelerator pedal. Standard Voltage: Fluctuates between 0.4 V or less and 0.5 V or more. NG Go to step 14 OK 8 PERFORM CONFIRMTION DRIVING PTTERN NEXT
TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM 145 9 CHECK WHETHER DTC OUTPUT RECURS (DTC P0136) (a) (b) On the intelligent tester, select the following menu items: DIGNOSIS / ENHNCED OD II / DTC INFO / CURRENT COD. Read DTCs. Result Display (DTC Output) P0136 No output Proceed To CHECK FOR INTERMITTENT PROLEMS 10 REPLCE HETED OXYGEN SENSOR NEXT 11 PERFORM CONFIRMTION DRIVING PTTERN NEXT 1 CHECK WHETHER DTC OUTPUT RECURS (DTC P0136) (a) (b) On the intelligent tester, select the following menu items: DIGNOSIS / ENHNCED OD II / DTC INFO / CURRENT COD. Read DTCs. Result Display (DTC Output) P0136 No output Proceed To REPIR COMPLETED 13 PERFORM CTIVE TT USING INTELLIGENT TTER (INJECTION VOLUME) (a) Connect the intelligent tester to the DLC3. (b) Start the engine and turn the tester ON. (c) Warm up the engine. (d) Select the following menu items: DIGNOSIS / ENHNCED OD II / CTIVE TT / INJ VOL. (e) Change the fuel injection volume using the tester, monitoring the voltage output of ir-fuel Ratio (/F) and HO sensors displayed on the tester.
146 TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM Change the fuel injection volume within the range of -1 % and +1 %. The injection volume can be changed in 1 % graduations within the range. The /F sensor is displayed as FS 1S1, and the HO sensor is displayed as OS 1S, on intelligent testers. Result Display (DTC Output) Voltage Variations Proceed To FS 1S1 (/F) FS 1S1 (/F) FS 1S1 (/F) lternates between more and less than 3.3 V Remains at more than 3.3 V Remains at less than 3.3 V normal HO sensor voltage (OS 1S) reacts in accordance with increases and decreases in fuel injection volumes. When the /F sensor voltage remains at either less or more than 3.3 V despite the HO sensor indicating a normal reaction, the /F sensor is malfunctioning. OK NG NG +1 % Injection Volume Malfunction -1 % /F Sensor Output 3.3 V Normal 1 V HO Sensor Output Malfunction 0 V 11606E01 NG REPLCE IR FUEL RTIO SENSOR OK CHECK ND REPIR EXTREMELY RICH OR LEN CTUL IR FUEL RTIO (INJECTOR, FUEL PRSURE, EXHUST GS LEKGE, ETC.)
TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM 147 14 CHECK FOR EXHUST GS LEKGE OK: No gas leakage. NG REPIR OR REPLCE EXHUST GS LEKGE POINT OK 15 INSPECT HETED OXYGEN SENSOR (HETER RISTNCE) Component Side: HO Sensor H3 Sensor + HT1 E OX1 (a) (b) Disconnect the H3 HO sensor connector. Measure the resistance between the terminals of the HO sensor connector. Standard Resistance Tester Connections HT1 (H3-1) - + (H3-) HT1 (H3-1) - E (H3-4) Specified Conditions 11 to 16 Ω at 0 C (68 F) 10 kω or higher Front View 058685E04 (c) Reconnect the HO sensor connector. NG REPLCE HETED OXYGEN SENSOR OK 16 INSPECT EFI RELY (a) (b) Remove the EFI relay from the engine room R/. Check the EFI relay resistance. Standard Resistance Tester Connections Specified Conditions 3-5 10 kω or higher 3-5 elow 1 Ω (when battery voltage applied to terminals 1 and ) 054773E0 (c) Reinstall the EFI relay. NG REPLCE EFI RELY OK
148 TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM 17 CHECK HRNS OR CONNECTOR (HETED OXYGEN SENSOR - ECM) Wire Harness Side: H3 HT1 Sensor OX1 HO Sensor Connector + E (a) (b) (c) Disconnect the H3 HO sensor connector. Turn the ignition switch to ON. Measure the voltage between the + terminal of the HO sensor connector and body ground. Standard Voltage Tester Connections Specified Conditions + (H3-1) - ody ground 9 to 14 V E4 Front View ECM Connector (d) (e) (f) Turn the ignition switch to OFF. Disconnect the E4 ECM connector. Check the resistance. Standard Resistance (Check for open) Tester Connections HT1 (H3-1) - HT1 (E4-) Specified Conditions elow 1 Ω OX1 (H3-3) - OX1 (E4-5) elow 1 Ω E (H3-4) - E (E4-8) elow 1 Ω OX1 E HT1 Standard Resistance (Check for short) Tester Connections Specified Conditions 14109E01 HT1 (H3-1) or HT1 (E4-) - ody ground 10 kω or higher OX1 (H3-3) or OX1 (E4-5) - ody ground 10 kω or higher E (H3-4) or E (E4-8) - ody ground 10 kω or higher (g) (h) Reconnect the HO sensor connector. Reconnect the ECM connectors. Reference (System Diagram of ank 1 Sensor ) From attery EFI EFI EFI No. Heated Oxygen Sensor Heater + HT1 HT1 E Sensor OX1 OX1 E ECM Duty Control MREL Ground 10383E7
TR-FE ENGINE CONTROL SYSTEM SFI SYSTEM 149 NG REPIR OR REPLCE HRNS OR CONNECTOR OK REPLCE HETED OXYGEN SENSOR