Page 1353 of 3419

EC-162Revision: October 2005
POWER SUPPLY AND GROUND CIRCUIT
2005 QX56
Ground Inspection UBS00H0H
Ground connections are very important to the proper operation of electrical and electronic circuits. Ground
connections are often exposed to moisture, dirt and other corrosive elements. The corrosion (rust) can
become an unwanted resistance. This unwanted resistance can change the way a circuit works.
Electronically controlled circuits are very sensitive to proper grounding. A loose or corroded ground can drasti-
cally affect an electronically controlled circuit. A poor or corroded ground can easily affect the circuit. Even
when the ground connection looks clean, there can be a thin film of rust on the surface.
When inspecting a ground connection follow these rules:
Remove the ground bolt or screw.
Inspect all mating surfaces for tarnish, dirt, rust, etc.
Clean as required to assure good contact.
Reinstall bolt or screw securely.
Inspect for “add-on” accessories which may be interfering with the ground circuit.
If several wires are crimped into one ground eyelet terminal, check for proper crimps. Make sure all of the
wires are clean, securely fastened and providing a good ground path. If multiple wires are cased in one
eyelet make sure no ground wires have excess wire insulation.
For detailed ground distribution information, refer to PG-29, "
Ground Distribution" .
PBIB1870E
Page 1354 of 3419

DTC U1000, U1001 CAN COMMUNICATION LINE
EC-163
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: October 20052005 QX56
DTC U1000, U1001 CAN COMMUNICATION LINEPFP:23710
DescriptionUBS00H0I
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic 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 2
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.
On Board Diagnosis LogicUBS00H0J
*1: This self-diagnosis has the one trip detection logic.
*2: The MIL will not light up for this diagnosis.
DTC Confirmation ProcedureUBS00H0K
1. Turn ignition switch ON and wait at least 3 seconds.
2. Select “DATA MONITOR” mode with CONSULT-II.
3. If 1st trip DTC is detected, go to EC-165, "
Diagnostic Procedure" .
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
U1000*
1
1000*1
CAN communication line
ECM cannot communicate to other control
units.
ECM cannot communicate for more than the
specified time.
Harness or connectors
(CAN communication line is open or
shorted) U1001*
2
1001*2
Page 1355 of 3419
EC-164Revision: October 2005
DTC U1000, U1001 CAN COMMUNICATION LINE
2005 QX56
Wiring DiagramUBS00H0L
BBWA1671E
Page 1356 of 3419
DTC U1000, U1001 CAN COMMUNICATION LINE
EC-165
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: October 20052005 QX56
Diagnostic ProcedureUBS00H0M
Go to LAN-3, "Precautions When Using CONSULT-II" .
Page 1357 of 3419

EC-166Revision: October 2005
DTC P0037, P0038, P0057, P0058 HO2S2 HEATER
2005 QX56
DTC P0037, P0038, P0057, P0058 HO2S2 HEATERPFP:226A0
DescriptionUBS00H0N
SYSTEM DESCRIPTION
The ECM performs ON/OFF control of the heated oxygen sensor 2 heater corresponding to the engine speed,
amount of intake air and engine coolant temperature.
OPERATION
CONSULT-II Reference Value in Data Monitor ModeUBS00H0O
Specification data are reference values.
On Board Diagnosis LogicUBS00H0P
Sensor Input signal to ECM ECM function Actuator
Camshaft position sensor (PHASE)
Crankshaft position sensor (POS)Engine speed
Heated oxygen sensor 2
heater controlHeated oxygen sensor 2 heater
Engine coolant temperature sensor Engine coolant temperature
Mass air flow sensor Amount of intake air
Engine speed rpm Heated oxygen sensor 2 heater
Above 3,600OFF
Below 3,600 rpm after the following conditions are met.
Engine: After warming up
Keeping the engine speed between 3,500 and 4,000 rpm for 1
minute and at idle for 1 minute under no loadON
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 HTR (B1)
HO2S2 HTR (B2)
Engine speed is below 3,600 rpm after the following conditions are met.
–Engine: After warming up
–Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no loadON
Engine speed: Above 3,600 rpm OFF
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0037
0037
(Bank 1)
Heated oxygen sensor 2
heater control circuit lowThe current amperage in the heated oxygen sen-
sor 2 heater circuit is out of the normal range.
(An excessively low voltage signal is sent to ECM
through the heated oxygen sensor 2 heater.)
Harness or connectors
(The heated oxygen sensor 2 heater
circuit is open or shorted.)
Heater oxygen sensor 2 heater P0057
0057
(Bank 2)
P0038
0038
(Bank 1)
Heated oxygen sensor 2
heater control circuit highThe current amperage in the heated oxygen sen-
sor 2 heater circuit is out of the normal range.
(An excessively high voltage signal is sent to
ECM through the heated oxygen sensor 2
heater.)
Harness or connectors
(The heated oxygen sensor 2 heater
circuit is shorted.)
Heater oxygen sensor 2 heater P0058
0058
(Bank 2)
Page 1358 of 3419
DTC P0037, P0038, P0057, P0058 HO2S2 HEATER
EC-167
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: October 20052005 QX56
DTC Confirmation ProcedureUBS00H0Q
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is between 10.5V and 16V at
idle.
WITH CONSULT-II
1. Turn ignition switch ON and select “DATA MONITOR” mode with CONSULT-II.
2. Start engine and warm it up to the normal operating tempera-
ture.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Start the engine and keep the engine speed between 3,500 rpm
and 4,000 rpm for at least 1 minute under no load.
5. Let engine idle for 1 minute.
6. If 1st trip DTC is detected, go to EC-171, "
Diagnostic Procedure"
.
WITH GST
Follow the procedure “WITH CONSULT-II” above.
SEF 1 74 Y
Page 1359 of 3419
EC-168Revision: October 2005
DTC P0037, P0038, P0057, P0058 HO2S2 HEATER
2005 QX56
Wiring DiagramUBS00H0R
BANK 1
BBWA1672E
Page 1360 of 3419
DTC P0037, P0038, P0057, P0058 HO2S2 HEATER
EC-169
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: October 20052005 QX56
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
6GRHeated oxygen sensor 2
heater (bank 1)[Engine is running]
Warm-up condition
Engine speed is below 3,600 rpm after the
following conditions are met.
–Keeping the engine speed between 3,500
and 4,000 rpm for 1 minute and at idle for 1
minute under no load.0 - 1.0V
[Ignition switch: ON]
Engine: Stopped
[Engine is running]
Engine speed: Above 3,600 rpm.BATTERY VOLTAGE
(11 - 14V)