Federal Models

INSPECTION PROCEDURE
1. CHECK VOLTAGE BETWEEN TERMINALS VF1, VF2 AND E1 OF DATA LINK CONNECTOR (DLC1).



- Warm up engine at normal operating temperature.
- Connect terminals TE1 and E1 of data link connector (DLC1).
- Connect positive prove to terminal VF1, VF2 and negative prove to terminal E1 of DLC1.
- Warm up the oxygen sensor by running engine at 2,500 rpm for about 2 minutes.
- Then, maintaining engine at 2,500 rpm, count how many times needle of voltmeter fluctuates between 0 and 5 volts;
^ Needle fluctuates of 8 times or more for every ten seconds; OK
^ Needle continues at 0.0 volts; proceed to step 2.
^ Needle continues at 5.0 volts; proceed to step 7.

2. CHECK VOLTAGE BETWEEN TERMINALS OX1, OX2 AND E1 OF DLC1.



- Warm up engine at normal operating temperature.
- Measure voltage between terminals OX1, OX2 and E1 of DLC1 when engine is suddenly raced to full throttle.
Voltage should be 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 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 or step 2. The numbers in the table below show the order in which the checks should be performed.



^ If OK proceed to step 5.
^ If not OK repair or replace.

5. CHECK COMPRESSION.
^ If OK proceed to step 6.
^ If not OK repair or replace.

6. DOES MALFUNCTION DISAPPEAR WHEN A GOOD 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. The numbers in the table below 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 OXYGEN SENSOR IS INSTALLED?
^ If YES replace oxygen sensor.
^ If NO check and replace ECM.