1998 DODGE RAM 1500 Transmission pressure solenoid

8W-30 FUEL/IGNITION SYSTEM
Component Page
A/C Compressor Clutch Relay............ 8W-30-9, 58
A/C Pressure Transducer......... 8W-30-23, 28, 29, 45
Accelerator Pedal Position Sensor . . . 8W-30-29, 47, 64, 65
Adjustable Pedal Motor................. 8W-30-61
Adjustable Pedal Relay.................. 8W-30-61
Adjustable Pedal Switch................. 8W-30-61
Ambient Temperature Sensor............. 8W-30-30
Auto Shut Down Relay................... 8W-30-4
Battery............................ 8W-30-52
Battery Temperature Sensor............ 8W-30-12, 56
Brake Lamp Switch............. 8W-30-8, 36, 57, 63
Camshaft Position Sensor........ 8W-30-10, 29, 45, 46
Capacitor........................... 8W-30-13
Clockspring..................... 8W-30-8, 36, 59
Coil On Plug No. 1.................. 8W-30-14, 39
Coil On Plug No. 2.................. 8W-30-15, 37
Coil On Plug No. 3.................. 8W-30-14, 39
Coil On Plug No. 4.................. 8W-30-15, 37
Coil On Plug No. 5.................. 8W-30-16, 39
Coil On Plug No. 6.................. 8W-30-13, 37
Coil On Plug No. 7.................. 8W-30-16, 39
Coil On Plug No. 8.................. 8W-30-13, 37
Condenser Fan Relay.................... 8W-30-9
Controller Antilock Brake............ 8W-30-6, 11, 57
Crankshaft Position Sensor............ 8W-30-10, 46
Data Link Connector............... 8W-30-9, 22, 55
Data Link Connector-Engine.............. 8W-30-51
EGR Solenoid................... 8W-30-28, 29, 32
Electronic Throttle Control Module.......... 8W-30-35
Engine Control Module....... 8W-30-42, 43, 44, 45, 46,
47, 48, 49, 50, 51, 52, 53, 54,
55, 56, 57, 58, 59, 60, 62, 63, 64, 65
Engine Coolant Temperature Sensor.... 8W-30-23, 41, 47
Engine Oil Pressure Switch.......... 8W-30-2, 53, 56
EVAP/Purge Solenoid................... 8W-30-12
Front Control Module................... 8W-30-61
Fuel Control Actuator................... 8W-30-50
Fuel Heater......................... 8W-30-60
Fuel Heater Relay..................... 8W-30-60
Fuel Injector No. 1.................. 8W-30-14, 40
Fuel Injector No. 2.................. 8W-30-15, 38
Fuel Injector No. 3.................. 8W-30-14, 40
Fuel Injector No. 4.................. 8W-30-15, 38
Fuel Injector No. 5.................. 8W-30-14, 40
Fuel Injector No. 6.................. 8W-30-15, 38
Fuel Injector No. 7.................. 8W-30-16, 40
Fuel Injector No. 8.................. 8W-30-13, 38
Fuel Injector Pack No. 1................. 8W-30-42
Fuel Injector Pack No. 2............ 8W-30-42, 43, 44
Fuel Injector Pack No. 3................. 8W-30-44
Fuel Pump Module................... 8W-30-3, 58
Fuel Pump Motor...................... 8W-30-48
Fuel Pump Relay....................... 8W-30-3
Fuse 2.............................. 8W-30-4
Fuse 5........................... 8W-30-25, 62
Fuse 12............................ 8W-30-60
Fuse 17............................. 8W-30-3
Fuse 19............................ 8W-30-52
Fuse 23............................. 8W-30-2Component Page
Fuse 36.......................... 8W-30-54, 61
Fuse 40............................ 8W-30-61
Fuse 49............................. 8W-30-4
Fuse 50..................... 8W-30-2, 55, 58, 62
Fusible Link......................... 8W-30-52
G104........................ 8W-30-3, 8, 25, 60
G105............................ 8W-30-56, 58
G107........... 8W-30-2, 7, 15, 18, 19, 20, 21, 30, 32
G114 .............................. 8W-30-53
G120............................ 8W-30-51, 60
G201............................... 8W-30-6
G202.............................. 8W-30-61
Generator......................... 8W-30-7, 51
Idle Air Control Motor................... 8W-30-9
Ignition Switch..................... 8W-30-6, 22
Inlet Air Temperature Sensor............. 8W-30-49
Input Speed Sensor.................... 8W-30-24
Instrument Cluster.................... 8W-30-30
Intake Air Heater Relay No. 1............. 8W-30-56
Intake Air Heater Relay No. 2............. 8W-30-56
Intake Air Temperature Sensor.......... 8W-30-23, 41
Intake Air Temperature/Manifold Absolute
Pressure Sensor..................... 8W-30-50
Integrated Power Module.... 8W-30-2, 3, 4, 9, 25, 52, 54,
55, 58, 60, 61, 62, 64
Knock Sensor........................ 8W-30-31
Knock Sensor-Left..................... 8W-30-33
Knock Sensor-Right.................... 8W-30-33
Lift Pump Motor...................... 8W-30-51
Line Pressure Sensor................... 8W-30-17
Manifold Absolute Pressure Sensor..... 8W-30-23, 29, 41
Natural Vacuum Leak Detection Assembly..... 8W-30-7
Output Speed Sensor................. 8W-30-24, 62
Oxygen Sensor 1/1 Upstream........... 8W-30-20, 21
Oxygen Sensor 1/2 Downstream......... 8W-30-18, 19
Oxygen Sensor 2/1 Upstream........... 8W-30-20, 21
Oxygen Sensor 2/2 Downstream......... 8W-30-18, 19
Oxygen Sensor Downstream Relay........... 8W-30-4
Power Steering Pressure Switch............ 8W-30-7
Powertrain Control Module....... 8W-30-2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19, 20, 21, 22, 23, 24,
25, 26, 27, 28, 29, 30, 31, 32,
33, 35, 36, 37, 38, 39, 40, 41
PTCNo.1 ....................... 8W-30-3, 9, 58
Pto Switch........................... 8W-30-6
Speed Control Servo.................. 8W-30-8, 63
Speed Control Switch-Left............. 8W-30-36, 59
Speed Control Switch-Right............ 8W-30-36, 59
Starter Motor Relay.................. 8W-30-2, 64
Throttle Position Sensor................. 8W-30-17
Tow/Haul Overdrive Switch............. 8W-30-6, 64
Transmission Control Relay............ 8W-30-25, 62
Transmission Range Sensor............... 8W-30-64
Transmission Solenoid Assembly......... 8W-30-54, 62
Transmission Solenoid/TRS Assembly . 8W-30-5, 25, 26, 27
Vacuum Pump........................ 8W-30-58
Vistronic Fan Drive.................... 8W-30-54
Water In Fuel Sensor................ 8W-30-47, 48
DR8W-30 FUEL/IGNITION SYSTEM 8W - 30 - 1

8W-31 TRANSMISSION CONTROL SYSTEM
Component Page
Automatic Day/Night Mirror........... 8W-31-7
Brake Lamp Switch.................. 8W-31-9
Camshaft Position Sensor.............. 8W-31-6
Clockspring........................ 8W-31-10
Clutch Interlock Brake Switch......... 8W-31-11
Data Link Connector................ 8W-31-16
Engine Control Module......... 8W-31-7, 8, 9, 10
Front Control Module................. 8W-31-2
Fuse 5.......................... 8W-31-2, 8
Fuse 38.......................... 8W-31-2, 7
Fuse 43........................... 8W-31-11
Fuse 50............................ 8W-31-8
G104..................... 8W-31-2, 11, 14, 16
G107............................. 8W-31-14
G201........................... 8W-31-3, 10
Input Speed Sensor.................. 8W-31-5
Instrument Cluster................ 8W-31-7, 14
Integrated Power Module....... 8W-31-2, 7, 8, 11Component Page
Line Pressure Sensor................. 8W-31-6
Output Speed Sensor............... 8W-31-5, 8
Powertrain Control Module..... 8W-31-2, 3, 4, 5, 6
Speed Control Servo.................. 8W-31-9
Speed Control Switch-Left............ 8W-31-10
Speed Control Switch-Right........... 8W-31-10
Starter Motor Relay................. 8W-31-11
Tow/Haul Overdrive Switch......... 8W-31-3, 10
Transfer Case Control
Module.............. 8W-31-11, 12, 13, 14, 16
Transfer Case Mode Sensor........ 8W-31-12, 13
Transfer Case Selector Switch......... 8W-31-14
Transfer Case Shift Motor............ 8W-31-16
Transmission Control Relay.......... 8W-31-2, 8
Transmission Range Sensor............ 8W-31-7
Transmission Solenoid Assembly........ 8W-31-8
Transmission Solenoid/TRS Assembly . 8W-31-2, 3, 4
DR8W-31 TRANSMISSION CONTROL SYSTEM 8W - 31 - 1

8W-80 CONNECTOR PIN-OUTS
Component Page
4WD Switch (Manual Transfer Case)..... 8W-80-5
A/C Compressor Clutch (Diesel)......... 8W-80-5
A/C Compressor Clutch (Gas)........... 8W-80-5
A/C Heater Control C1................ 8W-80-5
A/C Heater Control C2................ 8W-80-6
A/C Pressure Transducer (Diesel)........ 8W-80-6
A/C Pressure Transducer (NGC)......... 8W-80-6
Accelerator Pedal Position Sensor (5.7L) . . 8W-80-6
Accelerator Pedal Position Sensor
(Diesel M/T)...................... 8W-80-7
Accelerator Pedel Position Sensor
(Diesel A/T)....................... 8W-80-7
Adjustable Pedal Motor (Except Memory) . 8W-80-7
Adjustable Pedal Switch (Except Memory) . 8W-80-8
Airbag Control Module C1............. 8W-80-8
Airbag Control Module C2............. 8W-80-9
Airbag-Left Curtain.................. 8W-80-9
Airbag-Passenger On/Off Switch....... 8W-80-10
Airbag-Passenger Squib.............. 8W-80-10
Airbag-Right Curtain................ 8W-80-10
Ambient Temperature Sensor.......... 8W-80-10
Amplifier Audio C1 (Premium)......... 8W-80-11
Amplifier Audio C2 (Premium)......... 8W-80-11
Ashtray Lamp...................... 8W-80-11
Automatic Day/Night Mirror C1 (Except
Base).......................... 8W-80-12
Automatic Day/Night Mirror C2
(Telematics)..................... 8W-80-12
Back-Up Lamp Switch............... 8W-80-12
Battery Temperature Sensor........... 8W-80-12
Blend Door Actuator (Single Zone)...... 8W-80-13
Blower Motor...................... 8W-80-13
Blower Motor Resistor Block.......... 8W-80-13
Brake Fluid Level Switch............. 8W-80-13
Brake Lamp Switch................. 8W-80-13
Brake Transmission Shift Interlock
Solenoid........................ 8W-80-14
C102 (NGC)....................... 8W-80-14
C103............................. 8W-80-14
C106 (5.7L A/T).................... 8W-80-14
C106 (5.7L A/T).................... 8W-80-15
C107 (5.7L)........................ 8W-80-15
C107 (5.7L)........................ 8W-80-16
C108 (Diesel)...................... 8W-80-16
C108 (Diesel)...................... 8W-80-16
C109 (Diesel)...................... 8W-80-17
C109 (Diesel)...................... 8W-80-17
C110 (Diesel)...................... 8W-80-17
C110 (Diesel)...................... 8W-80-18
C112 (Diesel M/T)................... 8W-80-18
C112 (Diesel M/T)................... 8W-80-18
C112 (Diesel A/T)................... 8W-80-18Component Page
C112 (Diesel A/T)................... 8W-80-19
C130 (Diesel)...................... 8W-80-19
C131 (4.7L Electronic Transfer Case).... 8W-80-20
C131 (4.7L Electronic Transfer Case).... 8W-80-20
C131 (5.7L/Diesel).................. 8W-80-20
C131 (5.7L/Diesel).................. 8W-80-21
C131 (3.7L/4.7L Except Electronic
Transfer Case)................... 8W-80-21
C131 (3.7L/4.7L Except Electronic
Transfer Case)................... 8W-80-22
C200............................. 8W-80-22
C200............................. 8W-80-23
C201............................. 8W-80-23
C201............................. 8W-80-23
C202............................. 8W-80-24
C202............................. 8W-80-24
C206............................. 8W-80-24
C206............................. 8W-80-24
C207............................. 8W-80-24
C207............................. 8W-80-25
C216............................. 8W-80-25
C216............................. 8W-80-25
C217............................. 8W-80-26
C217............................. 8W-80-26
C218............................. 8W-80-26
C218............................. 8W-80-27
C219............................. 8W-80-27
C219............................. 8W-80-29
C220............................. 8W-80-30
C220............................. 8W-80-31
C250 (Hands Free).................. 8W-80-31
C250 (Hands Free).................. 8W-80-32
C301............................. 8W-80-32
C301............................. 8W-80-32
C301............................. 8W-80-33
C302............................. 8W-80-33
C302 (SLT)........................ 8W-80-34
C304............................. 8W-80-34
C304............................. 8W-80-34
C305 (SLT)........................ 8W-80-35
C305 (SLT)........................ 8W-80-35
C306............................. 8W-80-36
C306............................. 8W-80-36
C308............................. 8W-80-36
C308............................. 8W-80-37
C309............................. 8W-80-37
C309............................. 8W-80-37
C311 ............................. 8W-80-38
C311 ............................. 8W-80-38
C313............................. 8W-80-38
C313............................. 8W-80-39
C315............................. 8W-80-39
DR8W-80 CONNECTOR PIN-OUTS 8W - 80 - 1

ENGINE CONTROL MODULE C2 (DIESEL) - 50 WAY
CAV CIRCUIT FUNCTION
1- -
2- -
3 K615 18VT/WT INLET AIR TEMPERATURE SENSE
3 K615 18BR/WT (M/T) INLET AIR TEMPERATURE SENSE
4 V35 18VT/OR (A/T) S/C VENT CONTROL
5 K176 18BR/OR INTAKE AIR HEATER RELAY NO 2 CONTROL
6 K174 18BR/YL INTAKE AIR HEATER RELAY NO 1 CONTROL
7 V32 18VT/YL (A/T) SPEED CONTROL SUPPLY
8- -
9 T41 18YL/DB (A/T) PARK/NEUTRAL POSITION SWITCH SENSE (T41)
10 K161 18BR/LB FAN SPEED SENSOR
11 B22 18DG/YL VEHICLE SPEED SENSOR SIGNAL NO. 1
12 G6 18VT/GY OIL PRESSURE SIGNAL
13 T6 18DG (A/T) TOW/HAUL OVERDRIVE OFF SWITCH SENSE
14 T118 18DG (A/T) GOVERNOR PRESSURE SOLENOID CONTROL
15 T9 18DG/TN (A/T) 3-4 SOLENIOD CONTROL
16 D21 18WT/BR SCI TRANSMIT (PCM)
16 D21 18PK (M/T) SCI TRANSMIT
17 - -
18 T38 18YL/BR (A/T) GOVERNOR PRESSURE SENSOR SIGNAL
19 D20 18WT/LG SCI RECEIVE (PCM)
20 A209 16RD FUSED B(+)
21 Z902 16BK GROUND
22 - -
23 F856 18YL/PK 5 VOLT SUPPLY
24 K900 18DB/DG SENSOR GROUND
25 T75 18YL/LB (A/T) TORQUE CONVERTER CLUTCH SOLENOID CONTROL
26 N4 18DB/WT FUEL LEVEL SENSOR SIGNAL
27 - -
28 D25 18WT/VT PCI BUS
29 T54 18DG/OR (A/T) TRANSMISSION TEMPERATURE SENSOR SIGNAL
30 A209 16RD FUSED B(+)
31 T515 18YL/DB (A/T) TRANSMISSION CONTROL RELAY CONTROL
32 F202 18PK/GY FUSED IGNITION SWITCH OUTPUT (RUN-START)
33 K854 18VT/BR (M/T) 5 VOLT SUPPLY
34 V36 18VT/YL (A/T) S/C VACUUM CONTROL
35 K616 18BR/YL INLET AIR PRESSURE SENSE
36 V32 18VT/YL (M/T) SPEED CONTROL SUPPLY
37 B29 18DG/WT BRAKE SWITCH SIGNAL
38 - -
39 - -
40 A209 16RD FUSED B(+)
41 C13 18LB/OR A/C CLUTCH RELAY CONTROL
42 - -
43 K160 18BR/OR PARK LOCKOUT SOLENOID CONTROL
44 T14 18DG/BR (A/T) OUTPUT SPEED SENSOR SIGNAL
45 T13 18DG/VT (A/T) SENSOR GROUND
46 V37 18VT S/C SWITCH NO. 1 SIGNAL
47 K25 18DB/VT BATT TEMP SIGNAL
48 K400 18BR/VT (M/T) APPS NO.2 RETURN
49 Z902 16BK GROUND
50 Z902 16BK GROUND
8W - 80 - 60 8W-80 CONNECTOR PIN-OUTSDR

POWERTRAIN CONTROL MODULE C4 (NGC) - GREEN 38 WAY
CAV CIRCUIT FUNCTION
1 T60 18YL/GY OVERDRIVE SOLENOID CONTROL
2 T259 18YL/DG 4C SOLENOID CONTROL
3- -
4 T118 18DG MS SOLENOID CONTROL
5- -
6 T219 18YL/LG 2C SOLENOID CONTROL
7- -
8 T59 18YL/LB UNDERDRIVE SOLENOID CONTROL
9- -
10 T20 18DG/WT L/R SOLENOID CONTROL
11 T140 18YL/GY PRESSURE CONTROL SOLENOID CONTROL
12 Z908 18BK GROUND
13 Z977 18BK GROUND
14 Z904 18BK (A/T) GROUND
15 T1 18DG/LB TRS T1 SENSE
16 T3 18DG/DB TRS T3 SENSE
17 T6 18DG TOW/HAUL OVERDRIVE OFF SWITCH SENSE
18 T515 20YL/DB TRANSMISSION CONTROL RELAY CONTROL
19 T16 18YL/OR TRANSMISSION CONTROL RELAY OUTPUT
20 T48 18BR/YL 4C PRESSURE SWITCH SENSE
21 T29 18YL/WT UNDERDRIVE PRESSURE SWITCH SENSE
22 T9 18DG/TN OVERDRIVE PRESSURE SWITCH SENSE
23 - -
24 - -
25 - -
26 T4 18DG/LB TRS T2 SENSE
27 - -
28 T16 18YL/OR TRANSMISSION CONTROL RELAY OUTPUT
29 T50 18YL/TN LOW/REVERSE PRESSURE SWITCH SENSE
30 T147 18DG/YL 2C PRESSURE SWITCH SENSE
31 T38 18YL/BR LINE PRESSURE SENSOR SIGNAL
32 T14 18DG/BR OUTPUT SPEED SENSOR SIGNAL
33 T52 18DG/OR INPUT SPEED SENSOR SIGNAL
34 T13 18DG/VT SPEED SENSOR GROUND
35 T54 18DG/OR TRANSMISSION TEMPERATURE SENSOR SIGNAL
36 - -
37 T42 18DG/YL TRS T42 SENSE
38 T16 18YL/OR TRANSMISSION CONTROL RELAY OUTPUT
DR8W-80 CONNECTOR PIN-OUTS 8W - 80 - 91

TRANSMISSION RANGE SENSOR-6WAY
CAV CIRCUIT FUNCTION
1 L10 18WT/GY FUSED IGNITION SWITCH OUTPUT (RUN)
2 T117 20DG/YL TRANS RANGE SENSOR ELECTRONIC CLUSTER 5
VOLT SUPPLY
3- -
4 L1 18WT/LG BACKUP LAMP FEED
5 T917 20YL/TN TRANS RANGE SENSOR ELECTRONIC CLUSTER MUX
6 T41 20YL/DB PARK NEUTRAL POSITION SWITCH SENSE (T41)
6 T41 18YL/DB PARK NEUTRAL POSITION SWITCH SENSE (T41)
TRANSMISSION SOLENOID ASSEMBLY (48RE)-8WAY
CAV CIRCUIT FUNCTION
1 T16 18YL/OR TRANSMISSION CONTROL RELAY OUTPUT
2 F856 18YL/PK 5 VOLT SUPPLY
3 K900 20DB/DG SENSOR GROUND
3 K900 18DB/DG SENSOR GROUND
4 T38 18YL/BR GOVERNOR PRESSURE SENSOR SIGNAL
5 T118 18DG GOVERNOR PRESSURE SOLENOID CONTROL
6 T9 18DG/TN 3-4 SHIFT SOLENOID
7 T75 18YL/LB TORQUE CONVERTER CLUTCH SOLENOID CONTROL
8 T54 18DG/OR TRANSMISSION TEMPERATURE SENSOR SIGNAL
TRANSMISSION SOLENOID/TRS ASSEMBLY (NGC) - 23 WAY
CAV CIRCUIT FUNCTION
1 L10 18WT/GY FUSED IGNITION SWITCH OUTPUT (RUN)
2 T20 18DG/WT L/R SOLENOID CONTROL
3- -
4 T41 20YL/DB TRS T41 SENSE
5 T42 18DG/YL TRS T42 SENSE
6 L1 18WT/LG BACKUP LAMP FEED
7 T60 18YL/GY OVERDRIVE SOLENOID CONTROL
8 T3 18DG/DB TRS T3 SENSE
9 T1 18DG/LB TRS T1 SENSE
10 T16 18YL/OR TRANSMISSION CONTROL RELAY OUTPUT
11 T48 18BR/YL 4C PRESSURE SWITCH SENSE
12 T140 18YL/GY PRESSURE CONTROL SOLENIOD CONTROL
13 T4 18DG/LB TRS T2 SENSE
14 T50 18YL/TN LOW/REVERSE PRESSURE SWITCH SENSE
15 T147 18DG/YL 2C PRESSURE SWITCH SENSE
16 T9 18DG/TN OVERDRIVE PRESSURE SWITCH SENSE
17 T59 18YL/LB UNDERDRIVE SOLENOID CONTROL
18 T29 18YL/WT UNDERDRIVE PRESSURE SWITCH SENSE
19 T259 18YL/DG 4C SOLENOID CONTROL
20 T219 18YL/LG 2C SOLENOID CONTROL
21 T118 18DG MS SOLENOID CONTROL
22 K900 18DB/DG SENSOR GROUND
23 T54 18DG/OR TRANSMISSION TEMPERATURE SENSOR SIGNAL
8W - 80 - 102 8W-80 CONNECTOR PIN-OUTSDR

IDENTIFICATION
Transmission identification numbers are stamped
on the left side of the case just above the oil pan gas-
ket surface (Fig. 2). Refer to this information when
ordering replacement parts.
GEAR RATIOS
The 48RE gear ratios are:
1st.................................2.45:1
2nd................................1.45:1
3rd................................1.00:1
4th.................................0.69:1
Rev.................................2.20:1
OPERATION
The application of each driving or holding compo-
nent is controlled by the valve body based upon the
manual lever position, throttle pressure, and gover-
nor pressure. The governor pressure is a variable
pressure input to the valve body and is one of the
signals that a shift is necessary. First through fourth
gear are obtained by selectively applying and releas-
ing the different clutches and bands. Engine power is
thereby routed to the various planetary gear assem-
blies which combine with the overrunning clutch
assemblies to generate the different gear ratios. The
torque converter clutch is hydraulically applied and
is released when fluid is vented from the hydraulic
circuit by the torque converter control (TCC) solenoid
on the valve body. The torque converter clutch is con-
trolled by the Powertrain Control Module (PCM). The
torque converter clutch engages in fourth gear, and
in third gear under various conditions, such as when
the O/D switch is OFF, when the vehicle is cruising
on a level surface after the vehicle has warmed up.
The torque converter clutch can also be engaged in
the MANUAL SECOND gear position if high trans-
mission temperatures are sensed by the PCM. The
torque converter clutch will disengage momentarily
when an increase in engine load is sensed by the
PCM, such as when the vehicle begins to go uphill or
the throttle pressure is increased. The torque con-
verter clutch feature increases fuel economy and
reduces the transmission fluid temperature.
Since the overdrive clutch is applied in fourth gear
only and the direct clutch is applied in all ranges
except fourth gear, the transmission operation for
park, neutral, and first through third gear will be
described first. Once these powerflows are described,
the third to fourth shift sequence will be described.
1 - TORQUE CONVERTER 10 - OVERDRIVE CLUTCH
2 - INPUT SHAFT 11 - DIRECT CLUTCH
3 - OIL PUMP 12 - PLANETARY GEAR
4 - FRONT BAND 13 - INTERMEDIATE SHAFT
5 - FRONT CLUTCH 14 - OVERDRIVE OVERRUNNING CLUTCH
6 - REAR CLUTCH 15 - DIRECT CLUTCH SPRING
7 - PLANETARIES 16 - OVERDRIVE PISTON RETAINER
8 - REAR BAND 17 - OIL PAN
9 - OVERRUNNING CLUTCH 18 - VALVE BODY
Fig. 2 Transmission Part Number And Serial
Number Location
1 - PART NUMBER
2 - BUILD DATE
3 - SERIAL NUMBER
21 - 134 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)

DIRECT DRIVE POWERFLOW
The vehicle has accelerated and reached the shift
point for the 2-3 upshift into direct drive (Fig. 8).
When the shift takes place, the front band is
released, and the front clutch is applied. The rear
clutch stays applied as it has been in all the forward
gears. With the front clutch now applied, engine
torque is now on the front clutch retainer, which is
locked to the sun gear driving shell. This means that
the sun gear is now turning in engine rotation (clock-
wise) and at engine speed. The rear clutch is still
applied so engine torque is also still on the front
annulus gear. If two members of the same planetary
set are driven, direct drive results. Therefore, when
two members are rotating at the same speed and in
the same direction, it is the same as being locked up.
The rear planetary set is also locked up, given the
sun gear is still the input, and the rear annulus gear
must turn with the output shaft. Both gears are
turning in the same direction and at the same speed.
The front and rear planet pinions do not turn at all
in direct drive. The only rotation is the input from
the engine to the connected parts, which are acting
as one common unit, to the output shaft.
FOURTH GEAR POWERFLOW
Fourth gear overdrive range is electronically con-
trolled and hydraulically activated. Various sensor
inputs are supplied to the powertrain control module
to operate the overdrive solenoid on the valve body.
The solenoid contains a check ball that opens and
closes a vent port in the 3-4 shift valve feed passage.
The overdrive solenoid (and check ball) are not ener-
gized in first, second, third, or reverse gear. The vent
port remains open, diverting line pressure from the
2-3 shift valve away from the 3-4 shift valve. The
Tow/Haul control switch must be in the ON position
to transmit overdrive status to the PCM. A 3-4
upshift occurs only when the overdrive solenoid is
energized by the PCM. The PCM energizes the over-
drive solenoid during the 3-4 upshift. This causes the
solenoid check ball to close the vent port allowing
line pressure from the 2-3 shift valve to act directly
on the 3-4 upshift valve. Line pressure on the 3-4
shift valve overcomes valve spring pressure moving
the valve to the upshift position. This action exposes
the feed passages to the 3-4 timing valve, 3-4 quick
fill valve, 3-4 accumulator, and ultimately to the
overdrive piston. Line pressure through the timing
Fig. 8 Direct Drive Powerflow
1 - FRONT CLUTCH APPLIED 6 - INPUT SHAFT
2 - OVER-RUNNING CLUTCH FREE-WHEELING 7 - OVER-RUNNING CLUTCH FREE-WHEELING
3 - OUTPUT SHAFT 8 - REAR CLUTCH APPLIED
4 - REAR CLUTCH APPLIED 9 - FRONT CLUTCH APPLIED
5 - OUTPUT SHAFT 10 - INPUT SHAFT
DRAUTOMATIC TRANSMISSION - 48RE 21 - 139
AUTOMATIC TRANSMISSION - 48RE (Continued)