Hummer H1 Service Manual page 1144

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DTC P0335 Crankshaft Position (CKP) Sensor
Circuit Performance
C5
C27-D14
Circuit Description
The crankshaft position sensor is a "Hall-effect" type sensor
that monitors crankshaft position and speed. There are four
teeth 90 degrees apart on the front of the crankshaft sprocket
that induce a pulse in the sensor which is transmitted to the
PCM. There is a physical one to one correspondence between
the pump cam and crankshaft. This is a type A DTC.
Conditions for Setting the DTC
• RPM less than 300.
• 8 consecutive cam pulses missing for 8 #1 cylinder
events.
or
• RPM greater than or equal to 300.
• 8 consecutive cam pulses missing for 32 #1 cylinder
events.
Action Taken When the DTC Sets
Backup fuel.
Conditions for Clearing the MIL/DTC
• The PCM will turn the MIL off after three consecutive
trips without a fault condition.
• A History DTC will clear when forty consecutive
warm-up cycles that the diagnostic does not fail (coolant
temperature has risen 5°C (40°F) from start up coolant
05745159
A E
5 VOLT
REFERENCE
PUMP CAM HIGH
SENSOR RESOLUTION SENSOR
SIGNAL SIGNAL GROUND
B C D F
C3 B8 C1
C29-A4 C29-A2 C27-D9
5 VOLT CAM HIGH SENSOR
REFERENCE SENSOR RES GROUND
SIGNAL SIGNAL
PCM/Tech 1 Scan Tool 79
INJECTION TIMING
STEPPEN MOTOR (ITS)
OPTICAL/ FUEL
TEMP SENSOR
D A
C12 C2 A3 A2
C27-C8 A7 A8
C29
FUEL TEMP ITS ITS
SIGNAL HI LO
temperature and engine coolant temperature exceeds
71°C (160°F) that same ignition cycle).
• Use of a Scan Tool.
Diagnostic Aids
When PCM is in backup fuel, long crank times, fast idle and
poor performance conditions will exist. Check for good con-
nection at crankshaft position sensor and at PCM. Many inter-
mittent problems are caused by faulty electrical connections or
wiring. When attempting to diagnose an intermittent problem,
always begin by trying to reproduce the conditions under
which the failure occurs. This usually involves raising the en-
gine to a higher temperature or operating it near RPM that the
problem occurs. Since heat and vibration are often the cause of
intermittent, this may bring out the failure.
Test Description
Number(s) below refer to the number(s) on the diagnostic ta-
ble.
2. This step will determine if DTC P0335 is the result of a hard
failure or an intermittent condition.
4. This step checks the 5 volt reference circuit (the 5 volt refer-
ence may vary slightly).
5. This step checks the ground circuit.
M
B C
A6 A7
A9 A10
ITS ITS
LO HI
POWERTRAIN
CONTROL
MODULE
9-S12-070