Hummer H1 Service Manual page 311

5-112 Transmission/Transfer Case
DTC P1860 Torque Converter Clutch Pulse
Width Modulation Solenoid Electrical
Circuit Description
The Torque Converter Clutch Pulse Width Modulation Sole-
noid Valve (TCC PWM Sol. Valve) controls fluid acting on the
converter clutch valve, which then controls TCC apply and re-
lease. The TCC PWM Sol. Valve attaches to the control valve
body within the transmission. Ignition voltage goes directly to
the TCC PWM Sol. Valve. The Powertrain Control Module
(PCM) controls the TCC PWM Sol. Valve by providing a
ground path on circuit 418. The current flows through the TCC
PWM Sol. Valve coil according to the duty cycle (percentage
of ON and OFF time). The TCC PWM Sol. Valve provides a
smooth engagement of the torque converter clutch by operating
on a duty cycle percent of ON time.
If the PCM detects a continuous open or short to ground in the
TCC PWM Sol. Valve circuit or the TCC PWM Sol. Valve,
then DTC P1860 sets. DTC P1860 is a type A DTC.
Conditions For Setting DTC
a. System voltage is 10-16.5 volts.
b. The engine is running more than 475 RPM for greater
than 7 seconds.
TORQUE
CONVERTER
PRESSURE
CLUTCH
CONTROL
SOLENOID
SOLENOID
(TCC)
(PCS)
D C
C34
C32-F
C32-G
C27-C15 C27-C7
PCS PCS TCC PWM
LOW HIGH SOLENOID
CONTROL
___________________________________________
HOT IN RUN
AND START
FUSE 2A
10A
EXTERIOR
C33-F
C34-E
1-2 SHIFT
SOLENOID
(1-2)
2-3 SHIFT
SOLENOID
(2-3)
S B A
C32-E C32-D C32-C
C28-C5 C28-C6 C28-C4
2-3 SS 1-2 SS
CONTROL CONTROL
POWERTRAIN
CONTROL
MODULE
(PCM)
c. No shift solenoid DTCs P0751, P0753, P0756, and
P0758.
d. Commanded gear is D1.
e. All of the above conditions are met, and one of the
following conditions is met for 4.3 seconds out of 5
seconds.
• The PCM commands the solenoid OFF, and the voltage
remains below (zero volts).
• The PCM commands the solenoid to ON (100%) and
the voltage remains high (B+).
Action Taken When DTC Sets
• The PCM inhibits TCC engagement.
• The PCM inhibits 4th gear if in hot mode.
• The PCM illuminates the Malfunction Indicator Lamp
(MIL).
TRANSMISSION
FLUID
TEMPERATURE
SENSOR
(TFT)
M L
C32-J C32-H
C29-B12 C27-C9
SENSOR TFT
GROUND SENSOR
SIGNAL
9 - S 1 2 - 0 6 7
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