Inspection Procedure
INSPECTION PROCEDURE FOR DTC 25 AND 261. CHECK VOLTAGE BETWEEN TERMINALS VF1 AND E1 OF DATA LINK CONNECTOR (DLC1).
(a) Warm up engine at normal operating temperature.
(b) Connect terminals TE1 and E1 of data link connector (DLC1).
(c) Connect positive prove to terminal VF1 and negative prove to terminal E1 of DLC1.
(d) Warm up the oxygen sensor by running engine at 2,500 rpm for about 2 minutes.
(e) Then, maintaining engine at 2,500 rpm, count how many times needle of voltmeter fluctuates between 0.0 and 5.0 volts;
If needle fluctuates of 8 times or more for every ten seconds: OK
If needle continues at 0.0 volts; proceed to step 2.
If needle continues at 5.0 volts; proceed to step 7.
2. CHECK VOLTAGE BETWEEN TERMINALS OX1 AND E1 OF DLC1.
(a) Warm up engine at normal operating temperature.
(b) Measure voltage between terminals OX1 and E1 of DLC1 when engine is suddenly raced to full throttle.
OK if voltage is 0.5 volts or higher at least once within 1 second
- If OK proceed to step 7.
- If not OK proceed to step 3.
3. CHECK FOR OPEN AND SHORT IN HARNESS AND CONNECTOR BETWEEN ECM AND MAIN HEATED OXYGEN SENSOR; ECM AND DLC1.
- If OK proceed to step 4.
- If not OK repair or replace harness or connector.
4. CHECK EACH ITEM FOUND TO BE A POSSIBLE CAUSE OF PROBLEM.
- Check each circuit found to be a possible cause of trouble according to the results of the check in step 1 if the voltage remained at 0.0 volts, or step 2.
- The numbers in the table below show the order in which the checks should be performed.
1. Faulty sensor installation.
2. Air leakage
3. Misfire
4. Fuel system
5. Injector circuit
6. Characteristics deviation in engine coolant temperature sensor.
7. Characteristics deviation in intake air temperature sensor
8. Characteristics deviation in mass air flow meter
9. Valve timing
- If OK proceed to step 5.
- If not OK repair or replace faulty component.
5. CHECK COMPRESSION.
- If OK proceed to step 6.
- If not OK repair or replace.
6. DOES MALFUNCTION DISAPPEAR WHEN A GOOD MAIN HEATED OXYGEN SENSOR IS INSTALLED?
- If YES replace Oxygen Sensor.
- If NO check and replace ECM
7. CHECK EACH ITEM FOUND TO BE A POSSIBLE CAUSE OF PROBLEM.
- Check each circuit found to be a possible cause of trouble according to the results of the check in step 1.
Fig.18 - Possible Cause Chart:
Fig.18
- The numbers in Fig.18 show the order in which the checks should be performed.
- If OK proceed to step 8.
- If not OK repair or replace.
8. CHECK COMPRESSION.
- If OK proceed to step 9.
- If not OK repair or replace.
9. DOES MALFUNCTION DISAPPEAR WHEN A GOOD MAIN HEATED OXYGEN SENSOR IS INSTALLED?
- If YES replace oxygen sensor.
- If NO check and replace ECM.
CIRCUIT WIRING DIAGRAM
