Lexus NX manuals

Lexus NX: Diagnosis System

Lexus NX Service Manual / Engine & Hybrid System / 2ar-fxe (engine Control) / Sfi System / Diagnosis System

DIAGNOSIS SYSTEM

DESCRIPTION

When troubleshooting OBD II (On-Board Diagnostics) vehicles, the Techstream (complying with SAE J1978) must be connected to the DLC3 (Data Link Connector 3) of the vehicle. Various data in the vehicle's ECM (Engine Control Module) can be then read.

OBD II regulations require that the vehicle's on-board computer illuminates the MIL (Malfunction Indicator Lamp) on the instrument panel when the computer detects a malfunction in:

  1. The emission control system and components.
  2. The powertrain control components (which affect vehicle emissions).
  3. The computer itself.

In addition, the applicable DTCs prescribed by SAE J2012 are stored in the ECM memory. If the malfunction does not recur in 3 consecutive trips, the MIL turns off automatically but the DTCs remain stored in the ECM memory.

To check the DTCs, connect the Techstream to the DLC3. The Techstream displays output DTCs, freeze frame data, and a variety of engine data. The DTCs and freeze frame data can be cleared with the Techstream. In order to enhance OBD function on vehicles and develop the Off-Board diagnosis system, Controller Area Network (CAN) communication is used in this system. CAN is a network which uses a pair of data transmission lines spanning multiple computers and sensors. It allows for high speed communications between the systems and simplification of the wire harness connections.

NORMAL MODE AND CHECK MODE

The diagnosis system operates in normal mode during normal vehicle use. In normal mode, 2 trip detection logic is used to ensure accurate detection of malfunctions. Check mode is also available as an option for technicians. In check mode, 1 trip detection logic is used for duplicating malfunction symptoms and increasing the system's ability to detect malfunctions, including intermittent problems (Techstream only).

2 TRIP DETECTION LOGIC

When a malfunction is first detected, the malfunction is temporarily stored in the ECM memory (1st trip). If the same malfunction is detected during the subsequent drive cycle, the MIL is illuminated (2nd trip).

DLC3 (Data Link Connector 3)

(a) Check the DLC3.

Click here

FREEZE FRAME DATA

The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was moving or stationary, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data stored at the time of a malfunction.

AUXILIARY BATTERY VOLTAGE

Standard Voltage:

11 to 16 V

If the voltage is below 11 V, recharge or replace the auxiliary battery.

MIL (Malfunction Indicator Lamp)

(a) The MIL is illuminated when the power switch is on (IG).

(b) The MIL turns off when the power switch is on (READY). If the MIL remains illuminated, the diagnosis system has detected a malfunction or abnormality in the system.

HINT:

If the MIL is not illuminated when the power switch is on (IG), check the MIL circuit.

Click here

ALL READINESS

HINT:

  • With "All Readiness", you can check whether or not the DTC judgment has been completed by using the Techstream.
  • You should check "All Readiness" after simulating malfunction symptoms or for validation after finishing repairs.

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Clear the DTCs.

Click here

Powertrain > Engine and ECT > Clear DTCs

(e) Turn the power switch off and wait for at least 30 seconds.

(f) Turn the power switch on (IG) and turn the Techstream on.

(g) Perform the DTC judgment driving pattern to run the DTC judgment.

(h) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Powertrain > Engine and ECT > Utility

Tester Display

All Readiness

(i) Input the DTCs to be confirmed.

(j) Check the DTC judgment result.

Techstream Display

Description

NORMAL
  • DTC judgment completed
  • System normal

ABNORMAL
  • DTC judgment completed
  • System abnormal

INCOMPLETE
  • DTC judgment not completed
  • Perform the driving pattern after confirming DTC enabling conditions

N/A
  • Unable to perform DTC judgment
  • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

READ NEXT:

 Dtc Check / Clear

DTC CHECK / CLEAR NOTICE: When the diagnosis system is changed from normal mode to check mode or vice versa, all DTCs and freeze frame data recorded in normal mode are cleared. Before changing modes,

 Freeze Frame Data

FREEZE FRAME DATA DESCRIPTION The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in dete

 Check Mode Procedure

CHECK MODE PROCEDURE HINT: Compared to normal mode, check mode is more sensitive to malfunctions. Therefore, check mode can detect malfunctions that cannot be detected in normal mode. NOTICE: All the

SEE MORE:

 Customize Parameters

CUSTOMIZE PARAMETERS CUSTOMIZE INTELLIGENT CLEARANCE SONAR SYSTEM (a) Customizing with the Techstream. NOTICE: When the customer requests a change in a function, first make sure that the function can be customized. Be sure to make a note of the current settings before customizing. When troubl

 Adjustment

ADJUSTMENT CAUTION / NOTICE / HINT CAUTION: Radiofrequency radiation exposure information: This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment. This equipment should be kept with minimum distance of 20 cm (7.87 in.) between the radiator (antenna)

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