Hummer H1 Service Manual page 268

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DTC P0722 Output Speed Sensor Low Input
570 BK
8
GROUND
G2
Circuit Description
The speed sensor circuit consists of a magnetic induction type
sensor, which is the Output Shaft Speed (OSS) Sensor, a Vehi-
cle Speed Sensor (VSS) Buffer Module, and wiring. Gear teeth
pressed onto the output shaft carrier assembly induce an alter-
nating voltage into the sensor. This signal transmits to the VSS
Buffer Module. The VSS Buffer Module compensates for vari-
ous final drive ratios. The VSS Buffer Module also converts
the AC OSS Sensor signal into a 40 pulse per revolution (PPR)
DC 5 volt square wave form signal on circuit 437 to indicate
transmission output speed.
When the Powertrain Control Module (PCM) detects a low
output speed when the vehicle has a high engine speed in a
drive gear range, then DTC P0722 sets. DTC P0722 is a type B
DTC.
05745159
HOT IN
RUN AND START
FUSE
3A
20A
EXTERIOR
POWERTRAIN
CONTROL
MODULE
(PCM)
VEHICLE
SPEED
SENSOR
(VSS)
A B
TWISTED
PAIR
A B
C33
9 13 7
IGNITION VEHICLE SPEED
POSITIVE SENSOR SIGNAL
VOLTAGE
Transmission/Transfer Case
SPEEDO
A/T OUTPUT BUFFERED
SPEED SENSOR VSS
SIGNAL (VSS) SIGNAL
C29-A3 C29-A6
14 4
VSS BUFFERED
SIGNAL SPEED
OUTPUT SENSOR
SIGNAL
Conditions for Setting the DTC
• No TFP Val. Position Sw. DTC P1810.
• The APP Angle is greater than 12%.
• The engine torque must be 80-450 lb ft. (100-565 N•m).
• The engine speed must be 2000-3800 RPM.
• The A/T ISS Sensor speed is greater than 2000 RPM.
• The transmission is not in Park or Neutral.
• The engine vacuum is 0-105 kPa.
• The OSS Sensor speed is less than 200 RPM for at least
3 seconds.
Action Taken When the DTC Sets
• The PCM Defaults to maximum line pressure.
• The PCM freezes shift adapts.
• The PCM defaults to the calculated output speed value
using the Input Shaft Speed sensor values.
C3-P9
C1-18
11
SPEEDO
SIGNAL
VEHICLE
SPEED
SENSOR
BUFFER
(DRAC)
9-S12-068
5-69