OBD-II
PCM detects malfunctions related to engine sensors or actuators. OBD-II continuously monitors emission related components and can set Diagnostic Trouble Codes (DTCs), 1st trip DTCs, Freeze Frame data, 1st trip Freeze Frame data and SRT codes. This data, or DTC information, can be retrieved to assist in diagnosing problems. Using the Malfunction Indicator Light (MIL) to diagnose system faults is limited to code retrieval and fuel monitoring and is not recommended. It is recommended to use a OBD-II Generic Scan Tool (GST), or Nissan's CONSULT scan tool when performing self-diagnostic procedures, clearing PCM or performing a System Readiness Test (SRT).
When a malfunction is detected for the first time, the 1st trip DTC and 1st trip freeze frame data are stored in Powertrain Control Module (PCM) memory. However, in most 1st trip instances MIL will not be illuminated. If the same malfunction is detected, on the next vehicle trip, MIL will be illuminated as soon as the DTC is detected, or 2nd trip detection logic. If a misfire or fuel system malfunction should occur during 1st trip, MIL will be illuminated or flash. DTC and freeze frame information will be stored to aid in diagnostics by specifying operating conditions when DTC was set.
FREEZE FRAME DATA
Note. 1st trip freeze-frame data values can only be displayed with Nissan's CONSULT, and are not displayed on GST scan tool.
PCM records engine operating condition when an emission related fault is detected. This single "snapshot" is stored in PCM memory to aid in diagnostics by indicating conditions present when DTC is detected. Freeze-frame data is kept in order of priority. If low priority freeze-frame data (priority 1) is stored and another freeze-frame fault should occur, with the same priority, only the original freeze-frame data will remain. Always record this information when reviewing information.
If MIL should illuminate, indicating a 2nd trip malfunction or a higher priority code, the lower priority freeze-frame data would be replaced with the priority 2 or 3 freeze-frame data. Should a priority 3 malfunction occur (misfire, A/T or air/fuel system fault), then any other lower priority freeze-frame data would be replaced with priority 3 freeze-frame data. See FREEZE FRAME PRIORITY IDENTIFICATION table. This recorded data is useful for determining conditions in which the malfunction occurs.
Note. Only one 1st trip DTC and one freeze-frame data "snapshot" can be stored in PCM. If using GST, 1st trip DTC freeze-frame information may not be accessible. Use CONSULT to retrieve 1st trip DTC freeze-frame information.
| Priority | Items |
|---|---|
| 1 | Freeze Frame Data For Misfire DTC P0300-P0308; Fuel Injection System DTC P0171, P0172 |
| 2 | (1) 2nd Trip Freeze Frame Data |
| 3 | 1st Trip Freeze Frame Data |
| (1) Not In priority 1. | |
| (1) | Not In priority 1. |
FREEZE FRAME PRIORITY IDENTIFICATION
DATA MONITOR
Data monitor function allows viewing of PCM input and output signals in real time. Turn ignition off. Ensure scan tool is properly connected. Program scan tool using the following steps
- Select vehicle and engine selection menu (optional).
- Select year, engine, model and any additional information requested by scan tool (optional).
- Select GENERIC OBD-II OPTIONS.
- Select DATA MONITOR.
- Turn ignition on or start engine and allow to idle.
- Follow operating instructions from scan tool menu.
- Select input or output signal desired.
MALFUNCTION INDICATOR LIGHT (MIL)
Note. CHECK ENGINE or SERVICE ENGINE SOON light is now referred to as Malfunction Indicator Light (MIL).
Turn ignition on. Verify MIL is properly illuminated. If MIL does not illuminate, repair MIL circuit. Turn mode selector switch on PCM fully clockwise. MIL should turn off. Wait 2 seconds, and turn mode selector fully counterclockwise. System is now in diagnostic test mode II. Retrieve Diagnostic Trouble Codes (DTCs) by observing MIL, and counting the number of flashes. Record all codes set and then go to appropriate test procedure. MIL DTC numbering is different than CONSULT or GST DTC numbering. See appropriate DTC IDENTIFICATION table under DIAGNOSTIC TROUBLE CODE DEFINITIONS .
MIL Code Display
MIL Code is a 4 digit number indicated by 2 separate 2 digit numbers flashed by MIL. The 2 separate numbers are separated by a pause (.9 second). The first number will be long flashes (.6 second), and the second will be short flashes (.3 second). If there is more than one MIL DTC stored, there will be a 2.1 second pause between codes.
For example, 3 long (.6 second) flashes, a pause (.9 second), then followed by 3 short (.3 second) flashes of MIL indicate a MIL Code 0303. If 2 different MIL Codes are stored, such as 0406 and 0608, this would be displayed by 4 long flashes, pause, 6 short flashes, long pause, 6 long flashes, pause, 8 short flashes of MIL.
Erasing Stored Information
The following emission related information will be erased from PCM memory: DTCs stored, 1st trip DTCs, freeze frame data, 1st trip freeze frame data, System Readiness Test (SRT) codes and test values. To erase this information, turn ignition off. Turn mode selector lever on the PCM clockwise, wait 2 seconds and turn mode selector counterclockwise.
Using GST
Turn ignition off. Connect scan tool to DLC located under left side dash panel. see scheme 1 Turn ignition on. Enter program desired on GST screen. Perform each diagnostic mode according appropriate service procedure displayed on GST. As GSTs differ from manufacturer, the functions of GSTs will vary. For further information, see the appropriate Operation Manual of the manufacturer.
Typical GST modes available are listed with a brief definition of their function.
Mode 2: Freeze Frame Data
This mode gains access to emission-related data value information stored by PCM during the freeze frame portion of self-diagnostic mode. During engine operation, this mode may or may not store a Diagnostic Trouble Code (DTC). In this mode, MIL should be off, unless a DTC is present.
Mode 4: Clearing Codes
This mode can clear all emission related diagnostic information for DTCs, freeze frame data and reset system monitoring test results.
Mode 6: On-Board Tests
This mode accesses the results of on board diagnostic monitoring tests of specific components and systems that are not continuously monitored.
Mode 7: On-Board Tests
This mode enables the off board test drive to obtain test results for emission-related powertrain components and systems that are continuously monitored during normal driving conditions.
EQUIPMENT HOOK-UP
Ensure scan tool is OBD-II compliant. Turn ignition off. Connect data cable to OBD-II data link connector (located under left side of instrument panel). Plug power cable into cigarette lighter. Turn ignition on.
RETRIEVING CODES
Note. Procedures given are generic and may vary depending on equipment used. See scan tool manufacturer's instructions for specifics.
FAIL-SAFE MODE
If any malfunctions are detected in Mass Airflow (MAF) sensor, Engine Coolant Temperature (ECT) sensor, Throttle Position (TP) sensor, Traction Control System (TCS) or Powertrain Control Module (PCM) due to an open or short circuit, PCM will enter a fail-safe mode. Driveability will be poor and the MIL will be illuminated. Preprogrammed values will be used for engine operating conditions when PCM goes into fail-safe mode. See FAIL-SAFE MODE OPERATING CONDITIONS table. Refer to all diagnostic tests that apply for description and testing of circuit affected.
When a failure is detected in the Central Processing Unit (CPU) of PCM, MIL will be illuminated. When PCM is in fail-safe mode, fuel injection, ignition timing, fuel pump operation, IACV-AAC valve and cooling fan operation will be limited. DTC and other PCM information may not be accessible. If PCM fail-safe mode condition is confirmed, replace PCM.
| DTC (1) | Circuit | Engine Operating Condition |
|---|---|---|
| P0100 | MAF Sensor | 2400 RPM Or Less Due To Fuel Cut |
| P0110 | IAT Sensor | PCM Assumes IAT Sensor At 86°F (30°C) |
| P0115 | ECT Sensor | ECT Signal Fixed 104-107°F (40-80°C) Based On Engine Run Time |
| P0120 | TP Sensor | Poor Acceleration Based On MAF and RPM |
| P1335 | CKP Sensor | Ignition Timing Is Fixed. TDC Signal Is Controlled By CMP Sensor & CKP (Phase) Sensor |
| N/A | PCM | All Engine Controls Limited Not More Than 3000 RPM. Ignition Timing Is Fixed. (2) .Engine Running, Cooling Fan On. (2) Engine Running, Fuel Pump On |
| (1) Information may not be accessible from PCM. (2) If engine stalls, operation turns off. | ||
| (1) | Information may not be accessible from PCM. |
| (2) | If engine stalls, operation turns off. |
FAIL-SAFE MODE OPERATING CONDITIONS
CLEARING CODES
Note. Clearing code procedure will clear the following: Diagnostic trouble codes. 1st trip diagnostic trouble codes. Freeze frame data. 1st trip freeze frame data. System readiness codes. Test values. Other values relative to specific model. Ensure necessary freeze frame data and diagnostic trouble codes are recorded prior to clearing diagnostic information. Turning ignition off when in Mode 2 will not clear codes. Clear code procedure must be used. All diagnostic information will be erased if battery is disconnected for more than 24 hours.
Checking SRT Codes Status
With scan tool connected, choose SRT STATUS mode (with Nissan CONSULT scan tool) or MODE 1 (OBD-II generic scan tool). On Nissan CONSULT, Select DTC CONFIRMATION and check SRT codes status. On generic scan tool, follow manufacturer's instructions for accessing SRT codes. Categories will be either complete or incomplete. If any category is incomplete, follow SETTING SRT CODES procedure.
Setting SRT Codes
- With scan tool connected to Datalink Connector (DLC), start engine and allow vehicle to warm to operating temperature (coolant temp. at 158°F). Drive vehicle according to procedure described. (Scheme 4)
- Perform driving procedure one or more times. If driving procedure is interrupted, repeat procedure. On A/T models, operate vehicle with shift lever in "D" position with overdrive on. On M/T models, shift gears at specified intervals. See M/T SHIFT POINTS.
| Application | Shift Speed MPH | |
|---|---|---|
| Acceleration Below 4000 Ft. Elevation | ||
| 1-2 | 13 | |
| 2-3 | 23 | |
| 3-4 | 33 | |
| 4-5 | 39 | |
| Cruising Speed Below 4000 Ft. Elevation | ||
| 1-2 | 13 | |
| 2-3 | 16 | |
| 3-4 | 27 | |
| 4-5 | 36 | |
| Acceleration Above 4000 Ft. Elevation | ||
| 1-2 | 15 | |
| 2-3 | 25 | |
| 3-4 | 40 | |
| 4-5 | 45 | |
| Maximum Speed/Gear | ||
| 1 | 30 | |
| 2 | 60 | |
| 3 | 90 | |
M/T SHIFT POINTS
Scheme 4
FINAL CHECK FOR ALL CODE CHARTS
Unless otherwise instructed, perform following FINAL CHECK after each repair is completed.
- Clear all DTCs stored in PCM memory. See «CLEARING CODES»(ref-18070-S18556901412000122900000) under SELF-DIAGNOSTIC SYSTEM.
- Ensure pass code is displayed on scan tool.
- Perform a test drive.
- Verify no DTCs are present in PCM memory. If results are okay, inspection is complete. If results are not okay, repeat circuit test for remaining DTC(s). Ensure PCM pin terminals or harness connector is not damaged.
PATTERN 1
During Pattern 1, ensure the following conditions are true
- Coolant temperature is 14-95°F (- 10-35°C) when engine is started.
- Tank fuel temperature sensor is more than 32°F (0°C) when engine is started.
- Engine is operated at idle speed until coolant temperature is 158°F (70°C).
PATTERN 2
The time required to set codes may be extended if driving pattern is interrupted.
PATTERN 3
Follow specified driving pattern and repeat at least 3 times. See View "A". On models with M/T, follow specified shift points. See M/T SHIFT POINTS table.
PATTERN 4
All tests in this area are performed after the engine has been operated for at least 17 minutes. During Pattern 4, accelerator pedal must be held steady. If accelerator pedal is moved during this pattern, test must be repeated.
- Accelerate vehicle to 56 MPH (90 km/hr) then release accelerator and keep released for 10 seconds. After 10 seconds has passed, accelerate vehicle back to 56 MPH (90 km/hr) and hold.
- Stop vehicle and remain stopped for 10 seconds. Accelerate to 30-35 MPH (50-55 km/hr) within 10 seconds and maintain speed for 20 seconds. See «M/T SHIFT POINTS»(ref-18070-S07794883692000122900000) table for specified shift points on vehicles with manual transmission. During acceleration hold throttle steady, maintaining.8-1.2 volts on TP sensor as indicated by scan tool. Repeat this pattern at least 10 times or until the EGR system SRT is set.
- Use scan tool to determine vehicle speed.
- This driving pattern may be omitted if appropriate DTC is performed in DTC WORK SUPPORT mode using Nissan CONSULT scan tool. Generic scan tool may have a similar feature. Refer to scan tool manufacturer's instructions.
SUMMARY
If no DTCs (or only pass codes) are present, driveability symptoms exist or intermittent codes exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.