Condition of Error Detection
DTC (e.g. U1000 and U1001) of CAN communication is indicated on SELF-DIAG RESULTS on CONSULT if a CAN communication signal is not transmitted or received between units for 2 seconds or more.
CAN COMMUNICATION SYSTEM ERROR
- CAN communication line open (CAN-H, CAN-L, or both)
- CAN communication line short (ground, between CAN communication lines, other harnesses)
- Error of CAN communication control circuit of the unit connected to CAN communication line
ERROR EXAMPLE
Note. Each vehicle differs in symptom of each unit under fail-safe mode and CAN communication line wiring. Example: Main Line Between Data Link Connector and ABS Actuator and Electric Unit (Control Unit) Open Circuit
Scheme 17
| Unit name | Major symptom |
|---|---|
| ECM | Engine torque limiting is affected, and shift harshness increases. |
| BCM | Reverse warning chime does not sound. The front wiper moves under continuous operation mode even though the front wiper switch being in the intermittent position. |
| EPS control unit | The steering effort increases. |
| Combination meter | The shift position indicator and OD OFF indicator turn OFF. The speedometer is inoperative. The odo/trip meter stops. |
| ABS actuator and electric unit (control unit) | Normal operation. |
| TCM | No impact on operation. |
| IPDM E/R | When the ignition switch is ON, The headlamps (Lo) turn ON. The cooling fan continues to rotate. |
Example: TCM Branch Line Open Circuit
Scheme 18
| Unit name | Major symptom |
|---|---|
| ECM | Engine torque limiting is affected, and shift harshness increases. |
| BCM | Reverse warning chime does not sound. |
| EPS control unit | Normal operation. |
| Combination meter | Shift position indicator and O/D OFF indicator turn OFF. Warning lamps turn ON. |
| ABS actuator and electric unit (control unit) | Normal operation. |
| TCM | No impact on operation. |
| IPDM E/R | Normal operation. |
Note. The model (all units on CAN communication system are Diag on CAN) cannot perform CAN diagnosis with CONSULT if the following error occurs. The error is judged by the symptom.
| Error | Difference of symptom |
|---|---|
| Data link connector branch line open circuit | Normal operation. |
| CAN-H, CAN-L harness short-circuit | Most of the units which are connected to the CAN communication system enter fail-safe mode or are deactivated. |
Example: Data Link Connector Branch Line Open Circuit
Scheme 19
| Unit name | Major symptom |
|---|---|
| ECM | Normal operation. |
| BCM | |
| EPS control unit | |
| Combination meter | |
| ABS actuator and electric unit (control unit) | |
| TCM | |
| IPDM E/R |
Note. When data link connector branch line is open, transmission and reception of CAN communication signals are not affected. Therefore, no symptoms occur. However, be sure to repair malfunctioning circuit.
Example: CAN-H, CAN-L Harness Short Circuit
Scheme 20
| Unit name | Major symptom |
|---|---|
| ECM | Engine torque limiting is affected, and shift harshness increases. Engine speed drops. |
| BCM | Reverse warning chime does not sound. The front wiper moves under continuous operation mode even though the front wiper switch being in the intermittent position. The room lamp does not turn ON. The engine does not start (if an error or malfunction occurs while turning the ignition switch OFF.) The steering lock does not release (if an error or malfunction occurs while turning the ignition switch OFF.) |
| EPS control unit | The steering effort increases. |
| Combination meter | The tachometer and the speedometer do not move. Warning lamps turn ON. Indicator lamps do not turn ON. |
| ABS actuator and electric unit (control unit) | Normal operation. |
| TCM | No impact on operation. |
| IPDM E/R | When the ignition switch is ON, The headlamps (Lo) turn ON. The cooling fan continues to rotate. |
How to Use CAN Communication Signal Chart
The CAN communication signal chart lists the signals needed for trouble diagnosis. It is useful for detecting the root cause by finding a signal related to the symptom, and by checking transmission and reception unit.
Scheme 21
Scheme 22
INTERVIEW WITH CUSTOMER
Interview with the customer is important to detect the root cause of CAN communication system errors and to understand vehicle condition and symptoms for proper trouble diagnosis.
Points in interview
- What: Parts name, system name
- When: Date, Frequency
- Where: Road condition, Place
- In what condition: Driving condition/environment
- Result: Symptom
Notes for checking error symptoms
Scheme 23
- Check normal units as well as error symptoms. Example: Circuit between ECM and the combination meter is judged normal if the customer indicates tachometer functions normally.
- When a CAN communication system error is present, multiple control units may malfunction or go into failsafe mode.
- Indication of the combination meter is important to detect the root cause because it is the most obvious to the customer, and it performs CAN communication with many units.
CREATE INTERVIEW SHEET
Fill out the symptom described by the customer, vehicle condition, and CAN system type on the interview sheet.
Interview Sheet (Example)
Scheme 24
DETECT THE ROOT CAUSE
CAN diagnosis function of CONSULT detects the root cause.
Caution
- This section describes information peculiar to a vehicle and inspection procedures.
- For trouble diagnosis procedure, refer to " «TROUBLE DIAGNOSIS PROCEDURE»(ref-516393-S30854089482012120600000) ".
Precaution for Supplemental Restraint System (SRS) "AIR BAG" and "SEAT BELT PRE-TENSIONER"
The Supplemental Restraint System such as "AIR BAG" and "SEAT BELT PRE-TENSIONER", used along with a front seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain types of collision. This system includes seat belt switch inputs and dual stage front air bag modules. The SRS system uses the seat belt switches to determine the front air bag deployment, and may only deploy one front air bag, depending on the severity of a collision and whether the front occupants are belted or unbelted. Information necessary to service the system safely is included in the "SRS AIR BAG" and "SEAT BELT" of this Service Manual.
| WARNING | Always observe the following items for preventing accidental activation. To avoid rendering the SRS inoperative, which could increase the risk of personal injury or death in the event of a collision that would result in air bag inflation, all maintenance must be performed by an authorized NISSAN/INFINITI dealer. Improper maintenance, including incorrect removal and installation of the SRS, can lead to personal injury caused by unintentional activation of the system. For removal of Spiral Cable and Air Bag Module, see " SRS AIR BAG ". Never use electrical test equipment on any circuit related to the SRS unless instructed to in this Service Manual. SRS wiring harnesses can be identified by yellow and/or orange harnesses or harness connectors. |
PRECAUTIONS WHEN USING POWER TOOLS (AIR OR ELECTRIC) AND HAMMERS
| WARNING | Always observe the following items for preventing accidental activation. When working near the Air Bag Diagnosis Sensor Unit or other Air Bag System sensors with the ignition ON or engine running, never use air or electric power tools or strike near the sensor(s) with a hammer. Heavy vibration could activate the sensor(s) and deploy the air bag(s), possibly causing serious injury. When using air or electric power tools or hammers, always switch the ignition OFF, disconnect the battery, and wait at least 3 minutes before performing any service. |
CAN COMMUNICATION SYSTEM: CAN Communication Control Circuit
CAN communication control circuit is incorporated into the control unit and transmits/receives CAN communication signals.
Scheme 25
| Component | System description |
|---|---|
| CAN controller | It controls CAN communication signal transmission and reception, error detection, etc. |
| Transceiver IC | It converts digital signal into CAN communication signal, and CAN communication signal into digital signal. |
| Noise filter | It eliminates noise of CAN communication signal. |
| Termination circuit (1) (Resistance of approx. 120 ohms) | Generates a potential difference between CAN-H and CAN-L. |
| (1) These are the only control units wired with both ends of CAN communication system. | |
| (1) | These are the only control units wired with both ends of CAN communication system. |
CAN COMMUNICATION SYSTEM: CAN Communication Signal Chart
Refer to " HOW TO USE CAN COMMUNICATION SIGNAL CHART " for how to use CAN communication signal chart.
Note. Refer to " ABBREVIATION LIST " for the abbreviations of the connecting units.
Scheme 26
Scheme 27
Scheme 28
Note. CAN data of the air bag diagnosis sensor unit is not used by usual service work, thus it is omitted.
Interview Sheet
Note. Refer to " TROUBLE DIAGNOSIS PROCEDURE " for how to use interview sheet.
Scheme 29
Main Line
| Malfunction area | Reference |
|---|---|
| Main line between IPDM E/R and data link connector | " DIAGNOSIS PROCEDURE " |
| Main line between data link connector and air bag diagnosis sensor unit | " DIAGNOSIS PROCEDURE " |
| Main line between data link connector and multi display unit | " DIAGNOSIS PROCEDURE " |
Branch Line
| Malfunction area | Reference |
|---|---|
| ECM branch line circuit | " DIAGNOSIS PROCEDURE " |
| AWD control module branch line circuit | " DIAGNOSIS PROCEDURE " |
| ABS actuator and electric unit (control unit) branch line circuit | " DIAGNOSIS PROCEDURE " |
| IPDM E/R branch line circuit | " DIAGNOSIS PROCEDURE " |
| TCM branch line circuit | " DIAGNOSIS PROCEDURE " |
| Data link connector branch line circuit | " DIAGNOSIS PROCEDURE " |
| EPS control unit branch line circuit | " DIAGNOSIS PROCEDURE " |
| Combination meter branch line circuit | " DIAGNOSIS PROCEDURE " |
| Steering angle sensor branch line circuit | " DIAGNOSIS PROCEDURE " |
| Air bag diagnosis sensor unit branch line circuit | " DIAGNOSIS PROCEDURE " |
| A/C auto amp. branch line circuit | " DIAGNOSIS PROCEDURE " |
| Multi display unit branch line circuit | " DIAGNOSIS PROCEDURE " |
| BCM branch line circuit | " DIAGNOSIS PROCEDURE " |
Short Circuit
| Malfunction area | Reference |
|---|---|
| CAN communication circuit | " DIAGNOSIS PROCEDURE " |