Infiniti I35 (A33). Manual — part 274
SEC046D
Component Description
NHEC1250
Power steering pressure (PSP) sensor is installed to the power
steering high-pressure tube and detects a power steering load.
This sensor is a potentiometer which transforms the power steer-
ing load into output voltage, and emits the voltage signal to the
ECM. The ECM controls the electric throttle control actuator and
adjusts the throttle valve opening angle to increase the engine
speed and adjusts the idle speed for the increased load.
CONSULT-II Reference Value in Data Monitor
Mode
NHEC1256
Specification data are reference values.
MONITOR ITEM
CONDITION
SPECIFICATION
PW/ST SIGNAL
I
Engine: After warming up, idle the
engine
Steering wheel is in neutral position.
(Forward direction)
OFF
Steering wheel is turned.
ON
On Board Diagnosis Logic
NHEC1251
The MIL will not light up for this self-diagnosis.
NOTE:
If DTC P0550 is displayed with DTC P1229, first perform the trouble diagnosis for DTC P1229. Refer to
EC-539.
DTC No.
Trouble diagnosis name
DTC detecting condition
Possible cause
P0550
0550
Power steering pressure
sensor circuit
An excessively low or high voltage from the
sensor is sent to ECM.
I
Harness or connectors
(The sensor circuit is open or
shorted.)
I
Power steering pressure sensor
DTC Confirmation Procedure
NHEC1252
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.
With CONSULT-II
1.
Turn ignition switch ON.
2.
Select “DATA MONITOR” mode with CONSULT-II.
3.
Start engine and let it idle for at least 5 seconds.
4.
If 1st trip DTC is detected, go to EC-439, “Diagnostic Proce-
dure”.
With GST
Follow the procedure “WITH CONSULT-II” above.
GI
MA
EM
LC
FE
AT
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0550 PSP SENSOR
Component Description
EC-437
Wiring Diagram
NHEC1253
MEC640E
DTC P0550 PSP SENSOR
Wiring Diagram
EC-438
Specification data are reference values and are measured between each terminal and body 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
COLOR
ITEM
CONDITION
DATA (DC Voltage)
58
B
Sensor ground
[Engine is running]
I
Warm-up condition
I
Idle speed
Approximately 0V
89
G
Power steering pres-
sure sensor
[Engine is running]
I
Steering wheel is being turned.
0.5 - 4.0V
[Engine is running]
I
Steering wheel is not being turned.
0.4 - 0.8V
111
R
Sensor power supply
[Ignition switch ON]
Approximately 5V
Diagnostic Procedure
NHEC1254
1
CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten two engine ground screws.
Refer to “Ground Inspection”, EC-160.
SEC047D
OK or NG
OK
©
GO TO 2.
NG
©
Repair or replace ground connections.
GI
MA
EM
LC
FE
AT
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0550 PSP SENSOR
Wiring Diagram (Cont’d)
EC-439
2
CHECK PSP SENSOR POWER SUPPLY CIRCUIT
1. Disconnect PSP sensor harness connector.
2. Turn ignition switch ON.
SEC046D
3. Check voltage between PSP sensor terminal 1 and ground with CONSULT-II or tester.
SEC048D
Voltage: Approximately 5V
OK or NG
OK
©
GO TO 3.
NG
©
Repair harness or connectors.
3
CHECK PSP SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Disconnect TCM harness connector.
4. Check harness continuity between PSP sensor terminal 3 and ECM terminal 58, TCM terminal 42.
Refer to Wiring Diagram.
Continuity should exist.
5. Also check harness for short to power.
OK or NG
OK
©
GO TO 5.
NG
©
GO TO 4.
4
DETECT MALFUNCTIONING PART
Check the following.
I
Harness for open or short between ECM and PSP sensor
I
Harness for open or short between TCM (Transmission Control Module) and PSP sensor.
©
Repair open circuit or short to ground or short to power in harness or connectors.
DTC P0550 PSP SENSOR
Diagnostic Procedure (Cont’d)
EC-440
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