How to Troubleshoot Fuel and Emissions Systems (N22A)

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) or the glow plug indicator on the dash does not come on, check for poor connections or loose pins 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. With complex electronics (such as ECMs) this can sometimes mean something works, but not the way it's supposed to.

MIL Action

On these models, if you turn the ignition switch to the ON (II) position, without starting the engine, the malfunction indicator lamp will come on for about 20 seconds. It then goes off or blinks 5 times under various conditions. This is normal: it shows the self-testing condition of the diagnostics for the emissions control systems.

How to Check for DTCs with the HDS

When the ECM senses a malfunction in the system, the MIL (A) or the glow plug indicator (B) in the gauge assembly will come on.

When the HDS is connected to the data link connector (DLC) (A) (located under the driver's side of the dashboard), it will indicate the diagnostic trouble code (DTC) when the ignition switch is turned ON (II).

If the MIL or the glow plug indicator has been reported on, or if a drivability problem is suspected, follow this procedure:

1.	Connect the HDS to the DLC (see the HDS user's manual for specific instructions).

2.	Turn the ignition switch ON (II), select DIESEL system and observe the DTCs in the DTC MENU on the screen.

3.	Record all DTCs, and freeze data.

4.	Do the troubleshooting for the indicated DTCs.

5.	If you can't check the DTC and the MIL stays on, do the MIL circuit troubleshooting.

6.	If you can't check the DTC and the glow plug indicator stays on, do the glow plug indicator circuit troubleshooting.

If the MIL and/or the glow plug indicator does not come on

If the MIL and/or the glow plug indicator does not come on but there is a drivability problem, do the symptom troubleshooting.

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 DTC, do not continue through the procedure. To do so will only result in confusion and possibly, a needless replaced ECM.

HDS Clear Command

The inside ECM stores various specific data to correct the system even when there is no electrical power such as the battery negative terminal or No. 9 IGP (20 A) fuse are disconnected. But stored data based on failure parts should be cleared by using the ‘‘CLEAR COMMAND'' of the HDS, if parts are replaced.

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

DTC Clear

1.	Clear the DTC with the HDS with the engine stopped.

2.	Turn the ignition switch OFF, and wait 1 minute.

3.	Disconnect the HDS from the DLC.

ECM Reset

This command clears stored specific data from each vehicle such as DTC and freeze data.

1.	Reset the ECM with the HDS with the engine stopped.

2.	Turn the ignition switch OFF, and wait 1 minute.

3.	Disconnect the HDS from the DLC.

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

1.	Reset the ECM with the HDS.

2.	Turn the ignition switch OFF.

3.	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 Troubleshooting Circuit at the ECM Connectors

Special Tools Required
ECM test probe set ( 070AJ-RBD0200)

1.	Remove the center console.

2.	Remove the passenger's kick panel.

3.	Turn the ignition switch OFF, and wait 1 minute.

4.	Disconnect the ECM connectors (A), and probe the terminals from the terminal side of the connectors.

5.	Check the connector terminal diameter, and select the suitable pin probe (male).

6.	Connect one side of the patch cord (A) terminal to a commercially available digital multimeter (B), and connect the other side of the patch cord terminals to a tester probe.

7.	When diagnosis/troubleshooting is made at the ECM connector, use the measurement hole (A) above the terminal you need to check.

Gently slide the pin probe (male) into the connector terminals from the terminal side. Do not force the tips into the terminals.

For accurate results, always use the pin probe (male).
To prevent damage to the connector terminals, do not insert test equipment probes, paper clips, or other substitutes as they can damage the terminals. Damaged terminals cause a poor connection and an incorrect measurement.
Do not puncture the insulation on a wire. Punctures can cause poor or intermittent electrical connections.

ECM Updating and Substitution for Testing

Special Tools Required
Honda interface module ( (HIM) EQS05A35570)

Use this procedure when you have to substitute a known-good ECM in a troubleshooting procedure. Update the ECM only if the ECM does not have the latest software loaded.

NOTE: Do not turn the ignition switch OFF while updating the ECM. If you turn the ignition switch OFF before completion, the ECM can be damaged.

How to Update the ECM

NOTE:

Make sure you have the latest software on the HDS.
To ensure the latest program is installed, do a ECM update whenever the ECM is substituted or replaced.
You can not update a ECM with the program it already has. It will only accept a new program.
Before you update the ECM, make sure the battery is fully charged.
To prevent ECM damage, do not operate anything electrical (audio system, brakes, A/C, power windows, moonroof (if equipped), door locks, etc.) during the update.
If you need to diagnose the Honda interface module (HIM) because the HIM's red (#3) light came on or was flashing during the update, leave the ignition switch in the ON (II) position when you disconnect the HIM from the data link connector (DLC). This will prevent ECM damage.
High temperature in the engine compartment might cause the ECM to become too hot to run the update. If the engine has been running before this procedure, open the hood and cool the engine compartment.

1.	Turn the ignition switch ON (II), but do not start the engine.

2.	Connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.

3.	Make sure the HDS communicates with the ECM. If it doesn't, go to the DLC circuit troubleshooting.

4.	If the HDS does not have the update function, disconnect the HDS from the vehicle and connect the Honda interface module (HIM).

If the software in the ECM is the latest, disconnect the HDS or the HIM from the DLC, and go back to the procedure that you were doing.
If the software in the ECM is not the latest, do the ECM update procedure as described on the HIM label or in the ECM update system.

NOTE: If the ECM update system requires you to cool the ECM, follow what is shown on the screen.

How to Substitute the ECM

1.	Connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.

2.	Turn the ignition switch ON (II).

3.	Make sure the HDS communicates within the ECM. If it doesn't, go to the DLC circuit troubleshooting.

4.	Turn the ignition switch OFF, and wait 1 minute.

5.	Remove the center console.

6.	Remove the passenger's kick panel.

7.	Disconnect the ECM connectors (A).

8.	Remove the bracket (B), then remove the ECM (C).

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

10.	Turn the ignition switch ON (II). NOTE: DTC P0630 ‘‘VIN Not Programmed or Mismatch'' will be stored because VIN has not been programmed into the ECM. Ignore it, and continue this procedure.

11.	Input the VIN to the ECM with the HDS.

12.	Select the IMMOBILIZER SYSTEM with the HDS.

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

14.	Reset the ECM with 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:

PASSED: On-board diagnosis is successfully finished.
FAILED: On-board diagnosis has finished but failed.
NOT COMPLETED: The on-board diagnosis was running but is out of the enable conditions of the DTC.