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.
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 (CKP pattern learn, idle learn, readiness codes, 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 (see ECM IDLE LEARN PROCEDURE ); CKP pattern learn procedure; Test-drive to set readiness codes to complete (see HOW TO SET READINESS CODES ).
DTC Clear
- Clear the DTC with the HDS while the engine is stopped.
- Turn the ignition switch OFF.
- Turn the ignition switch ON (II), and wait 30 seconds.
- Turn the ignition switch OFF, and disconnect the HDS from the DLC.
How to End a Troubleshooting Session (required after any troubleshooting)
- Reset the ECM with the HDS.
- Do the ECM idle learn procedure (see «ECM IDLE LEARN PROCEDURE»(ref-221342-S09897997502006022400000) ).
- Turn the ignition switch OFF.
- 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
Special Tools Required
- Digital multimeter KS-AHM-32-003 (1) or a commercially available digital multimeter
- Backprobe set 07SAZ-001000A (2)
Scheme 2
Scheme 3
- Connect the backprobe adapters (A) to the stacking patch cords (B), and connect the cords to a digital multimeter (C).
- Using the wire insulation as a guide for the contoured tip of the backprobe adapter, gently slide the tip into the connector from the wire side until it touches the end of the wire terminal.
- 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. NOTE: Do not puncture the insulation on a wire. Punctures can cause poor or intermittent electrical connections.
Symptom Troubleshooting Index
When the vehicle has one of these symptoms, check for a diagnostic trouble code (DTC) with the HDS. If there is no DTC, do the diagnostic procedure for the symptom, in the sequence listed, until you find the cause.
| Symptom | Diagnostic procedure | Also check for |
|---|---|---|
| Engine will not start (MIL works OK, no DTCs set) | Test the battery (see BATTERY TEST ). Test the starter (see STARTER PERFORMANCE TEST ). Check the fuel pressure (see FUEL PRESSURE TEST ). Troubleshoot the fuel pump circuit (see FUEL PUMP CIRCUIT TROUBLESHOOTING ). | Low compression No ignition spark Intake air leaks Locked up engine Broken cam chain Contaminated fuel |
| Engine will not start (MIL works OK, no DTCs set, immobilizer indicator stays on or flashes) | Troubleshoot the immobilizer system (see TROUBLESHOOTING ). | |
| MIL comes on and stays on, or never comes on at all, no DTCs set | Troubleshoot the MIL circuit (see MIL CIRCUIT TROUBLESHOOTING ). | |
| Engine starts but stalls immediately (MIL works OK, no DTCs set, immobilizer indicator stays on or flashes) | Troubleshoot the immobilizer system (see TROUBLESHOOTING ). | |
| Engine is hard to start (MIL works OK, no DTCs set) | Test the battery (see BATTERY TEST ). Check the fuel pressure (see FUEL PRESSURE TEST ). Clean the throttle body (see THROTTLE BODY CLEANING ). | Low compression Intake air leaks Contaminated fuel Weak spark |
| Cold fast idle too low (MIL works OK, no DTCs set) | Do the ECM idle learn procedure (see ECM IDLE LEARN PROCEDURE ). Check the idle speed (see IDLE SPEED INSPECTION ). Clean the throttle body (see THROTTLE BODY CLEANING ). | |
| Cold fast idle too high (MIL works OK, no DTCs set) | Do the ECM idle learn procedure (see ECM IDLE LEARN PROCEDURE ). Check the idle speed (see IDLE SPEED INSPECTION ). Inspect/adjust the throttle cable (see THROTTLE CABLE ADJUSTMENT ). Do the throttle position learning check (see THROTTLE BODY TEST ). | |
| Idle speed fluctuates (MIL works OK, no DTCs set) | Do the ECM idle learn procedure (see ECM IDLE LEARN PROCEDURE ). Check the idle speed (see IDLE SPEED INSPECTION ). Inspect/adjust the throttle cable (see THROTTLE CABLE ADJUSTMENT ). Do the carbon accumulation check (see THROTTLE BODY TEST ). | Intake vacuum leaks |
| After warming up, idle speed is below specification without load (MIL works OK, no DTCs set) | Troubleshoot the alternator FR signal circuit (see ALTERNATOR FR SIGNAL CIRCUIT TROUBLESHOOTING ). Do the carbon accumulation check (see THROTTLE BODY TEST ). Troubleshoot the A/C signal circuit (see A/C SIGNAL CIRCUIT TROUBLESHOOTING ). | |
| After warming up, idle speed is above specification without load (MIL works OK, no DTCs set) | Inspect/adjust the throttle cable (see THROTTLE CABLE ADJUSTMENT ). Troubleshoot the alternator FR signal circuit (see ALTERNATOR FR SIGNAL CIRCUIT TROUBLESHOOTING ). Inspect the APP sensor (see APP SENSOR SIGNAL INSPECTION ). Troubleshoot the A/C signal circuit (see A/C SIGNAL CIRCUIT TROUBLESHOOTING ). | |
| Low power (MIL works OK, no DTCs set) | Check the fuel pressure (see FUEL PRESSURE TEST ). Inspect/adjust the throttle cable (see THROTTLE CABLE ADJUSTMENT ). | Low compression Incorrect camshaft timing Incorrect engine oil level |
| Engine stalls (MIL works OK, no DTCs set) | Do the ECM idle learn procedure (see ECM IDLE LEARN PROCEDURE ). Check the fuel pressure (see FUEL PRESSURE TEST ). Check the idle speed (see IDLE SPEED INSPECTION ). Troubleshoot the brake pedal position switch signal circuit (see BRAKE PEDAL POSITION SWITCH SIGNAL CIRCUIT TROUBLESHOOTING ). | Intake air leaks Faulty harness and sensor connections |
| Difficult to refuel (MIL works OK, no DTCs set) | Check the fuel vent tube between the EVAP canister and the fuel tank. Check the fuel tank vapor recirculation tube between the fuel pipe and the fuel tank. Replace the fuel tank vapor control float (see FUEL TANK VAPOR CONTROL FLOAT REPLACEMENT ). | Malfunctioning gas station filling nozzle. |
| Fuel overflows during refueling (No DTCs set) | Replace the fuel tank vapor control float (see FUEL TANK VAPOR CONTROL FLOAT REPLACEMENT ). | Malfunctioning gas station filling nozzle. |
| HDS does not communicate with the ECM or the vehicle | Troubleshoot the DLC circuit (see DLC CIRCUIT TROUBLESHOOTING ). |
SYMPTOM TROUBLESHOOTING INDEX
Self-diagnosis
The ECM detects a failure of a signal from a sensor or from another control unit and stores a Temporary DTC or a DTC. Depending on the failure, a DTC is stored in the either first or the second drive cycle. When a DTC is stored, the ECM turns on the malfunction indicator lamp (MIL) by supplying ground to the MIL circuit.
- One Drive Cycle Detection Method When an abnormality occurs in the signal from a sensor or from another control unit, the ECM stores a DTC and turns on the MIL.
- Two Drive Cycle Detection Method When an abnormality occurs in the signal from a sensor or from another control unit in the first drive cycle, the ECM stores a Temporary DTC. The MIL does not come on at this time. If the failure continues in the second drive cycle, the ECM stores a DTC and turns on the MIL.