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 and PCMs) this can sometimes mean something works, but not the way it's supposed to.

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).

4.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)/powertrain control module (PCM) 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/PCM 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/PCM.

HDS Clear Command


The ECM/PCM stores various specific data to correct the system even if there is no electrical power such as when the battery negative terminal or No. 19 FI MAIN (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 DTC clear, ECM/PCM 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/PCM reset command erases all stored DTC codes, freeze data, on-board snapshot, and all specific data to correct the system except crank pattern. If the crank pattern data in the ECM/PCM was cleared, you must do the crank pattern learn procedure. The crank pattern clear command erases only crank pattern data. This command is for repair of a misfire or the crank 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/PCM, and it clears all commands at the same time (crank 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/PCM idle learn procedure; crank 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/PCM Reset


1.Reset the ECM/PCM 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/PCM 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/PCM. 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 crank 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 Park or 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 A/T in 2 position, or M/T 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 A/T in 2 position, or M/T 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 crank pattern learn procedure is complete.

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


1.Reset the ECM/PCM with the HDS.

2.Do the ECM/PCM idle learn procedure.

3.Turn the ignition switch OFF.

4.Disconnect the HDS from the DLC.

NOTE: The ECM/PCM is part of the immobilizer system. If you replace the ECM/PCM, 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/PCM


NOTE: The ECM/PCM 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/PCM during this function, without jumping the SCS line first, can damage the ECM/PCM.

1.Jump the SCS line with the HDS.

2.Remove the cover (A).

 

3.Lift up the under-hood fuse/relay box (A).

 

4.Remove the expansion tank (B). Disconnect the ECM/PCM connectors (C), and probe the terminals from the terminal side of the connectors.

5.Check the terminal test port size, and select the suitable pin probe (male).

6.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).

 

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

 

8.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/PCM 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/PCM in a troubleshooting procedure. Update the ECM/PCM only if the ECM/PCM does not have the latest software loaded.

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

How to Update the ECM/PCM


NOTE:

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).

4.If the software in the ECM/PCM 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/PCM is not the latest, do the ECM/PCM update procedure as described on the HIM label or in the ECM/PCM update system.

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

5.Do the ECM/PCM idle learn procedure.

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

How to Substitute the ECM/PCM


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.Remove the battery.

4.Remove the cover (A).

 

5.Remove the bolts (A), then remove the ECM/PCM (B).

 

6.Disconnect the ECM/PCM connectors A (C), B (D), and C (E).

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

7.Install the ECM/PCM and the battery in the reverse order of removal.

8.Turn the ignition switch ON (II).

NOTE:
KE, KG, TR models: DTC P0630 ‘‘VIN Not Programmed or Mismatch'' will be stored because VIN has not been programmed into the ECM/PCM. Ignore it, and continue this procedure.

9.KE, KG, TR models: Input the VIN to the ECM/PCM with the HDS.

10.Update the ECM/PCM if it does not have the latest software.

11.Select the IMMOBILIZER SYSTEM with the HDS.

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

13.Reset the ECM/PCM with the HDS.

14.Do the ECM/PCM idle learn procedure.

15.Do the crank pattern learn procedure.

16.Enter the anti-theft code for the audio and set the colck.

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: