How to Troubleshoot Fuel and Emissions Systems

Intermittent Failures


The term ‘‘intermittent failure'' means a system may have had a failure, but it checks OK now. If the Malfunction Indicator Lamp (MIL) on the dash does not come on, check for poor connections or loose wires at all connectors related to the circuit that you are troubleshooting.

Opens and Shorts


‘‘Open'' and ‘‘Short'' are common electrical terms. An open is a break in a wire or at a connection. A short is an accidental connection of a wire to ground or to another wire. In simple electronics, this usually means something won't work at all. In complex electronics (like ECM's) this can sometimes mean something works, but not the way it's supposed to.

How to Use the HDS


If the MIL has come on


1.Start the engine and check the MIL (A).

 

2.If the MIL stays on, connect the HDS to the Data Link Connector (DLC) (A) located under the driver's side of the dashboard.

 

3.Turn the ignition switch ON (II).

4.Check the Diagnostic Trouble Code (DTC) and note it. Also check the freeze frame data. Refer to the DTC Troubleshooting Index and begin the appropriate troubleshooting procedure.

NOTE:

If the MIL did not stay

If the MIL did not come on but there is a driveability problem, do the Symptom Troubleshooting Index.

If you can't duplicate the DTC

Some of the troubleshooting requires you to reset the ECM and try to duplicate the DTC. If the problem is intermittent and you can't duplicate the code, do not continue through the procedure. To do so will only result in confusion and, possibly, a needlessly replaced ECM.

HDS Clear Command


The inside ECM stores various specific data to correct the system. But stored data based on failure parts should be cleared by using the ‘‘CLEAR COMMAND'' of the HDS, or there is no electrical power such as the battery negative terminal, or No. 20 (15A) fuse are disconnected, if parts are replaced.

The HDS has two kings of clear command to meet the purpose. They are DTC clear, ECM clear. DTC clear command erases all stored DTC codes and Freeze Data.This must be done with the HDS after reproducing DTC during troubleshooting in this service manual. ECM clear command erases all stored DTC codes, Freeze Data and all specific data to correct the system.

DTC CLEAR


1.Do the DTC CLEAR in the CLEAR MENU with the HDS with the engine stopped.

2.Turn the ignition switch OFF.

3.Turn the ignition switch ON (II). Wait for 30 seconds.

4.Turn the ignition switch OFF, and disconnect the HDS from the DLC.

ECM RESET


This command clears stored specific data from each vehicle such as DTC and Freeze Data. It does not clear CKP PATTERN data.

1.Do the ECM RESET in the CLEAR MENU with the HDS with the engine stopped.

2.Turn the ignition switch OFF.

3.Turn the ignition switch ON (II). Wait for 30 seconds.

4.Turn the ignition switch OFF, and disconnect the HDS from the DLC.

ETCS Learn Procedure


The ETCS learn procedure must be done so that the ECM can learn the throttle body initialization. Do the ETCS learn procedure whenever you do any of these actions:


1.Turn the ignition switch OFF.

2.Connect the HDS to the DLC.

3.Turn the ignition ON (II).

4.Do the ETCS LEARN in the FUNCTION MENU with the HDS.

  • If it is completed, turn the ignition switch OFF. ETCS learn procedure is completed.
  • If it is not completed, follow the HDS indication until this test is completed.

How to End a Troubleshooting Session (required after any troubleshooting)


1.Do the ECM RESET in the CLEAR MENU with the HDS.

2.Do the ETCS learn procedure.

3.Turn the ignition switch OFF.

4.Disconnect the HDS from the DLC.

NOTE: The ECM is part of the immobilizer system. If you replace the ECM, it will have a different immobilizer code. In order for the engine to start, you must rewrite the immobilizer code with the HDS.

How to Remove the ECM for Testing


If the inspection for a trouble code requires voltage or resistance checks at the ECM connectors, remove the ECM and test it:

1.Disconnect the negative cable from the battery.

2.Remove the passenger's dashboard under cover (A), side kick panel (B) and glove box inner case.

 

3.Disconnect the connectors (C), and remove the bols, then remove the ECM (D).

4.Install the ECM in the reverse order of removal.

5.Reconnect the negative cable to the battery.

6.Do the ETCS learn procedure.

How to Troubleshoot at the ECM


Special Tools Required
Test pin box (pin box 130 seem) (  07XAZ-0010100)
 

Test harness (  070AZ-PWE0100)


1.In case you measure the standard voltage of ECM, turn the ignition switch and wait for 10 seconds.

2.Connect the ECM test harness and test pin box between the ECM and connectors.

 

3.If you cannot get to the wire side of the connector or the wire side is sealed (A), disconnect the connector and probe the terminals (B) from the terminal side. Do not force the probe into the connector.



Do not puncture the insulation on a wire.Punctures can cause poor or intermittent electrical connections.
Do not force the probe into the ECM connector.

 

How to Substitute the ECM


1.Remove the ECM from the vehicle.

2.Install a known-good ECM.

3.Rewrite the immobilizer code with the ECM replacement procedure in the HDS; It allows you to start the engine.

4.After completing your tests, reinstall the original ECM and rewrite the immobilizer code with the ECM replacement procedure in the HDS.

OBD Status


The OBD Status shows the current system status of each DTC and all of the parameters. This function is used to see if the technician's repair was successfully finished. The results of diagnostic tests for the DTC are displayed as: