Dodge RAM TRUCK 1500 1995 Service Manual page 1392

B R
42RH/46RH/47RH TRANSMISSION DIAGNOSIS AND TESTING 21 -109
SHIFT
LEVER
POSITION
TRANSMISSION CLUTCHES A N D BANDS
©WRDRIVE CLUTCHES
SHIFT
LEVER
POSITION
FRONT
CLUTCH
FRONT
BAND
REAR
CLUTCH
REAR
BAND
O V E R R U N .
CLUTCH
OVERDRIVE
CLUTCH
DIRECT
CLUTCH
OVERRUN.
CLUTC>3
Reverse X
X
X
Drive Range
First
Second
Third
Fourth
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
2-Range
(Manual)
Second)
X X X
X
X
1-Range
(Manual
Low)
1
X
1 x
X X
X X
J9421-218
Fig. 2 Clutch And
If the transmission slips in fourth gear but not in
third gear, the overdrive clutch is slipping. By select­
ing another gear which does not use these clutches,
the slipping unit can be determined. For example, if
the transmission also slips in Reverse, the front
clutch is slipping. If the transmission does not slip in
Reverse, the rear clutch is slipping.
If slippage occurs during the 3-4 shift or only in
fourth gear, the overdrive clutch is slipping. Simi­
larly, if the direct clutch were to fail, the transmis­
sion would lose both reverse gear and overrun
braking in 2 position (manual second gear). If the
transmission slips in any other two forward gears,
the transmission rear clutch is probably slipping.
If the transmission will not shift to fourth gear, the
control switch, overdrive solenoid or related wiring
may also be the problem cause.
This process of elimination can be used to identify
a slipping unit and check operation. Proper use of
the Clutch and Band Application Chart is the key.
Although road test analysis will help determine the
slipping unit, the actual cause of a malfunction usu­
ally cannot be determined until hydraulic and air
pressure tests are performed. Practically any condi­
tion can be caused by leaking hydraulic circuits or
sticking valves.
Unless a malfunction is obvious, such as no
drive in D range first gear, do not disassemble
the transmission. Perform the hydraulic and
air pressure tests to help pinpoint the problem
cause.
Band Application
HYDRAULIC PRESSURE TEST
Hydraulic test pressures range from a low of one
psi (6.895 kPa) governor pressure, to 300 psi (2068
kPa) at the rear servo pressure port in reverse. Use
100 psi Gauge C-3292 to check pressure at the accu­
mulator, front servo and governor. Use 300 psi Gauge
C-3293-SP to check pressure at the rear servo and at
the overdrive port in fourth gear.
P R E S S U R E
TEST p&mw
LOCATIONS
There are pressure test ports at the accumulator,
front servo, and rear servo (Fig. 3).
Governor and overdrive clutch pressure test ports
are located at the left and right rear sides of the
case.
Line pressure is checked at the accumulator port
on the right side of the case. The front servo pressure
port is at the right side of the case just behind the
filler tube opening.
The rear servo and governor pressure ports are at
the right rear of the transmission case. The overdrive
clutch pressure port is at the left rear of the case.
An accurate tachometer and two test gauges are re­
quired for the pressure test. Test Gauge C-3292 has a
100 psi range and is used at the accumulator, gover­
nor, front servo, and overdrive pressure ports. Test
Gauge C-3293-SP has a 300 psi range and is used at
the rear servo port where pressures range from 250
to 290 psi. In cases where two test gauges are re­
quired, the 300 psi gauge can be used at any of the
other test ports.