Nissan Maxima Service and Repair Manual: DTC/circuit diagnosis

  • U1000 CAN comm circuit
  • Description CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle multiplex communication line with high data communication speed and excellent error detection ability. Many electronic control units are equipped onto a vehicle, and each control unit shares information and links with other control units during operation (not independent). In CAN communication, control units are connected with two communication lines (CAN-H line, CAN-L line) allowing a high rate of information transmission with less wiring. Each control unit transmits/receives data but selectively reads required data only. CAN Communication Signal Chart.

  • U1010 control unit (CAN)
  • Description Initial diagnosis of A/C auto amp. DTC Logic DTC DETECTION LOGIC Diagnosis Procedure 1.CHECK WITH SELF-DIAGNOSIS FUNCTION OF CONSULT Using CONSULT, perform "SELF-DIAGNOSIS RESULTS" of HVAC.

  • B257B, B257C ambient sensor
  • Description COMPONENT DESCRIPTION Ambient Sensor The ambient sensor (1) is installed to the front bumper reinforcement. It detects ambient temperature and converts it into a resistance value which is then input into the A/C auto amp. Ambient Sensor Circuit AMBIENT TEMPERATURE INPUT PROCESS The A/C auto amp. equips a processing circuit for the ambient sensor input. However, when the temperature detected by the ambient sensor increases quickly, the processing circuit retards the A/C auto amp. function. It only allows the A/C auto amp. to recognize an ambient temperature increase of 0.33C (0.6F) per 100 seconds. As an example, consider stopping for a few minutes after high-speed driving.

  • B2578, B2579 in-vehicle sensor
  • Description In-vehicle Sensor The in-vehicle sensor (1) is located on instrument lower cover (LH). It converts variations in compartment air temperature drawn from the aspirator into a resistance value. It is then input into the A/C auto amp. In-vehicle Sensor Circuit Aspirator The aspirator (1) is located on driver side of heater & cooling unit assembly. It produces vacuum pressure due to air discharged from the heater & cooling unit assembly, continuously taking compartment air in the aspirator. DTC Logic DTC DETECTION LOGIC NOTE: If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. DTC CONFIRMATION PROCEDURE 1.

  • B2581, B2582 intake sensor
  • Description Intake Sensor The intake sensor is located on the evaporator. It converts air temperature after it passes through the evaporator into a resistance value which is then input to the A/C auto amp. Intake Sensor Circuit DTC Logic DTC DETECTION LOGIC NOTE: If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. Refer to HAC- 30, "DTC Logic" or HAC-31, "DTC Logic". DTC CONFIRMATION PROCEDURE 1.CHECK WITH SELF-DIAGNOSIS FUNCTION OF CONSULT Using CONSULT, perform "SELF-DIAGNOSIS RESULTS" of HVAC. Check if any DTC No. is displayed in the self-diagnosis results.

  • B2630, B2631 sunload sensor
  • Description COMPONENT DESCRIPTION Sunload Sensor The sunload sensor (1) is located on the driver'side defroster grille. It detects sunload entering through windshield by means of a photo diode. The sensor converts the sunload into a current value, which is then input into the A/C auto amp. Sunload Sensor Circuit SUNLOAD INPUT PROCESS The A/C auto amp. also equips a processing circuit which averages the variations in detected sunload over a period of time. This prevents drastic swings in the air temperature control system operation due to small or quick variations in detected sunload. For example, consider driving along a road bordered by an occasional group of large trees.

  • B2632, B2633 air mix door motor (driver side)
  • Description COMPONENT DESCRIPTION Air Mix Door Motor (Driver side) The air mix door motor (driver side) (1) is attached to the heater & cooling unit assembly. It rotates so that the air mix door is opened or closed to a position set by the A/C auto amp. Motor rotation is then conveyed through a shaft and the air mix door position feedback is then sent to the A/C auto amp. by PBR built-in air mix door motor. DTC Logic DTC DETECTION LOGIC NOTE: If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. Refer to HAC- 30, "DTC Logic" or HAC-31, "DTC Logic". DTC CONFIRMATION PROCEDURE 1.

  • B2634, B2635 air mix door motor (passenger side)
  • Description COMPONENT DESCRIPTION Air Mix Door Motor (Passenger Side) The air mix door motor (passenger side) (1) is attached to the heater & cooling unit assembly. It rotates so that the air mix door is opened or closed to a position set by the A/C auto amp. Motor rotation is then conveyed through a shaft and the air mix door position feedback is then sent to the A/C auto amp. by PBR built-in air mix door motor. DTC Logic DTC DETECTION LOGIC NOTE: If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. DTC CONFIRMATION PROCEDURE 1.CHECK WITH SELF-DIAGNOSIS FUNCTION OF CONSULT Using CONSULT, perform "SELF-DIAGNOSIS RESULTS" of HVAC. Check if any DTC No.

  • B2636, B2637, B2638, B2639, B2654, B2655 mode door motor
  • Description COMPONENT DESCRIPTION Mode Door Motor The mode door motor (1) is attached to the heater & cooling unit assembly. It rotates so that air is discharged from the outlet set by the A/C auto amp. Motor rotation is conveyed to a link which activates the mode door DTC Logic DTC DETECTION LOGIC NOTE: If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. DTC CONFIRMATION PROCEDURE 1.CHECK WITH SELF-DIAGNOSIS FUNCTION OF CONSULT Using CONSULT, perform "SELF-DIAGNOSIS RESULTS" of HVAC. Check if any DTC No. is displayed in the self-diagnosis results. NOTE: If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. 2.

  • B263D, B263E, B263f intake door motor
  • Description COMPONENT DESCRIPTION Intake Door Motor The intake door motor (1) is attached to the blower unit. It rotates so that air is drawn from inlets set by the A/C auto amp. Motor rotation is conveyed to a lever which activates the intake door. DTC Logic DTC DETECTION LOGIC NOTE: If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. DTC CONFIRMATION PROCEDURE 1.CHECK WITH SELF-DIAGNOSIS FUNCTION OF CONSULT Using CONSULT, perform "SELF-DIAGNOSIS RESULTS" of HVAC. Check if any DTC No. is displayed in the self-diagnosis results. NOTE: If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. 2.

  • Blower motor
  • Description COMPONENT DESCRIPTION Brush-less Motor The blower motor utilizes a brush-less motor with a rotating magnet. Quietness is improved over previous motors where the brush was the point of contact and the coil rotated. Blower Motor Circuit Component Function Check 1.CHECK OPERATION Warm up the engine. Operate the fan control dial. Check that the fan speed and indicator are switched for all fan speeds. Diagnosis Procedure 1.CHECK WITH SELF-DIAGNOSIS FUNCTION OF CONSULT Using CONSULT, perform "SELF-DIAGNOSIS RESULTS" of HVAC. Check if any DTC No. is displayed in the self-diagnosis results. NOTE: If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. 2.

  • Magnet clutch
  • Description SYSTEM DESCRIPTION A/C auto amp. controls A/C compressor operation by ambient temperature and signal from ECM. Low Temperature Protection Control A/C auto amp. will turn the A/C compressor ON or OFF as determined by a signal detected by ambient sensor. When ambient temperature is greater than 4C (39F), the A/C compressor turns ON. The A/C compressor turns OFF when ambient temperature is less than 2.5C (37F). Component Function Check 1.FUNCTION INSPECTIONS Press AUTO switch. AUTO is indicated on the display. Press the A/C switch. Check that the indicator of the A/C switch turns on. Check visually and by sound that the compressor is operating.

  • Power supply and ground circuit
  • A/C AUTO AMP. A/C AUTO AMP.: Description COMPONENT DESCRIPTION A/C Auto Amp. (Air Conditioner Automatic Amplifier) The A/C auto amp. (1) has a built-in microcomputer that processes information sent from various sensors needed for air conditioner operation. The air mix door motor(s), the mode door motor, the intake door motor, the blower motor and the compressor are then controlled. When the various switches and temperature control dial are operated, data is input to the A/C auto amp. from the AV control unit using CAN communication. The A/C auto amp. is operated with control mechanisms.

Diagnosis system (HVAC)

U1000 CAN comm circuit