How to Troubleshoot the Fuel and Emissions Systems (L13A)

How to Troubleshoot the 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 pins at all connectors related to the circuit that you are troubleshooting. If the MIL was on but then went out, the original problem may have been intermittent.

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 brinks 5 times under various conditions. This is normal: it shows the self-testing condition of the diagnostics for the emissions control systems.

How to Use the HDS (Honda Diagnostic System)

If the MIL (Malfunction Indicator Lamp) 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).

Check the diagnostic trouble code (DTC) and note it. Also check the freeze data and/or on-board snapshot data, and download any data found. Then refer to the indicated DTC's troubleshooting, and begin the appropriate troubleshooting procedure.

NOTE:

Freeze data indicates the engine conditions when the first malfunction, misfire, or fuel trim malfunction was detected.
The HDS can read the DTC, freeze data, on-board snapshot current data, and other engine control module (ECM) data.
For specific operations, refer to the user's manual that came with the HDS.

5.	If no DTCs are found, go to MIL troubleshooting.

If the MIL did not stay on

If the MIL did not stay on but there is a driveability 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 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 ECM stores various specific data to correct the system even if there is no electrical power such as when the battery negative terminal or No. 9 IGP (15 A) fuse are disconnected. Stored data based on failed parts should be cleared by using the ‘‘CLEAR COMMAND'' of the HDS, if parts are replaced.

The HDS has three kinds of clear commands to meet this purpose. They are clear DTCs, ECM reset, and Crank pattern clear. DTC clear command erases all stored DTC codes, freeze data, and on-board snapshot. This must be done with the HDS after reproducing the DTC during troubleshooting.
The ECM reset command erases all stored DTC codes, freeze data, on-board snapshot, and all specific data to correct the system except Crank (CKP) pattern. If the Crank (CKP) pattern data in the ECM was cleared, you must do the Crank (CKP) pattern learn procedure. The Crank (CKP) pattern clear command erases only Crank (CKP) pattern data. This command is for repair of a misfire or the CKP sensor.

Scan Tool Clear Command

If you are using a generic scan tool to clear commands, be aware that there is only one setting for clearing the ECM, and it clears all commands at the same time (Crank (CKP) pattern learn, idle learn, freeze data, on-board snapshot, and DTCs). After you clear all commands, you then need to do these procedures, in this order: ECM idle learn procedure; Crank (CKP) pattern learn procedure.

DTC Clear

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

2.	Turn the ignition switch OFF.

3.	Turn the ignition switch ON (II), and wait for 30 seconds.

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

ECM Reset

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

2.	Turn the ignition switch OFF.

3.	Turn the ignition switch ON (II), and wait for 30 seconds.

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

5.	Do the ECM idle learn procedure.

Crank (CKP) Pattern Clear/Crank (CKP) Pattern Learn

Clear/Learn Procedure (with the HDS)

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 with the vehicle and the ECM. If it doesn't, troubleshoot the DLC circuit.

4.	Select CRANK PATTERN in the ADJUSTMENT MENU with the HDS.

5.	Select CRANK PATTERN LEARNING with the HDS, and follow the screen prompts.

6.	The CKP pattern learn procedure is complete.

Learn Procedure (without the HDS)

1.	Start the engine. Hold the engine speed at 3,000 rpm (min^-1) without load (in neutral) until the radiator fan comes on.

2.	Test-drive the vehicle on a level road: Decelerate (with the throttle fully closed) from an engine speed of 2,500 rpm (min^-1) down to 1,000 rpm (min^-1) with the transmission in 1st gear.

3.	Test-drive the vehicle on a level road: Decelerate (with the throttle fully closed) from an engine speed of 5,000 rpm (min^-1) down to 3,000 rpm (min^-1) with the transmission in 1st gear.

4.	Repeat step 2 and 3 several times.

5.	Turn the ignition switch OFF.

6.	Turn the ignition switch ON (II), and wait for 30 seconds. The CKP pattern learn procedure is complete.

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

1.	Reset the ECM with the HDS.

2.	Do the ECM idle 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 Troubleshoot Circuits at the ECM Connectors

NOTE: The ECM stays on up to 15 minutes after the ignition switch is turned OFF. Jumping the SCS line after turning the ignition switch OFF cancels this function. Disconnecting the ECM during this function, without jumping the SCS line first, can damage the ECM.

1.	Make sure you have the anti-theft code for the audio.

2.	Remove the battery.

3.	Jump the SCS line with the HDS.

4.	Remove the cover (A).

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

6.	Install the battery, then do this; Enter the anti-theft codes for the radio. Set the clock.

7.	Connect one side of the patch cord (A) terminals to a commercially available digital multimeter (B), and connect the other side of the patch cord terminals to a commercially available banana jack (Pomona Electronics Tool No. 3563 or equivalent) (C).

8.	When diagnosis/troubleshooting is done at the ECM connector, use the terminal test port (A) above the terminal you need to check.

Gently slide the pin probe (male) into the terminal test port 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, sunroof, 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.	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.

5.	Do the ECM idle learn procedure.

6.	Do the CKP pattern clear/CKP pattern learn procedure.

How to Substitute the ECM

1.	Make sure you have the anti-theft code for audio.

2.	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.	Make sure the HDS communicates with the vehicle and the ECM. If it doesn't, troubleshoot the DLC circuit.

5.	Remove the battery.

6.	Remove the cover (A).

7.	Remove the bolts (D), then remove the ECM (E).

8.	Disconnect the ECM connectors A, B, and C. NOTE: ECM connectors A, B, and C have symbols (A=¨, B=[utri], C=¡) embossed on them for identification.

9.	Install the ECM and the battery 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.	Update the ECM if it does not have the latest software.

13.	Select the IMMOBI SYSTEM with the HDS.

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

15.	Reset the ECM with the HDS.

16.	Do the ECM idle learn procedure.

17.	Do the CKP pattern learn procedure.

18.	Enter the anti-theft code for the audio and set the clock.

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.
EXECUTING: The vehicle is in enable criteria conditions for the DTC and the on board diagnosis is running.
NOT COMPLETED: The on board diagnosis was running but is out of the enable conditions of the DTC.
OUT OF CONDITION: The vehicle has stayed out of the enable conditions for the DTC.