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MegaShift 4L60E Wiring

The 4L60E is controlled through 14 pins. These are:

Inputs to GPIO
LTemperature Sensor Signal
MTemperature Sensor GND
NPressure Switch A (aka. Input1)
RPressure Switch B (aka. Input2)
PPressure Switch C (aka. Input3)
n/a2WD/4WD Input (ground for 4WD)
n/aVehicle Speed Sensor (VSS) - has its own 2-pin connector

Outputs from GPIO
ASol A (1-2/3-4) Switched GND (aka. Output1)On/Off20-40 Ohms (0.75 Amps Max.)
BSol B (2-3) Switched GND (aka. Output2)On/Off20-40 Ohms (0.75 Amps Max.)
CPressure Control Solenoid HighPower (nominal +12V)Switched 12V from harness
DPressure Control Switched GNDPWM (293Hz)0 to 60% (3.5 - 4.6 Ohms at 20°C, 1.1 Amps Max.)
E+12 Volt PowerHigh (nominal +12V)Switched 12V from harness
ULock-Up Feel Solenoid Switched GND not always usedPWM (32 Hertz) 10-11.5 Ohms at 20°C
S3-2 Sol Switched GND (aka. Output3)PWM (50Hz)9-14 Ohms at 20°C
TTorque Converter Clutch Solenoid Switched GNDOn/Off20-40 Ohms (1.5 Amps Max.)

The wiring inside the 4L60E transmission looks like this:

The corresponding AMPseal connections for the control/sense functions are:

AMPseal Pin
Sol A (Output1)PE4VB323
Sol B (Output2)PM2VB435
Sol32 (Output3)PT1PWM434
switchA (Input1)AD0EGT4 (jumper)26
switchB (Input2)AD1GPI26
switchC (Input3)AD3EGT325
Paddle UPPT6VR215
Temp SensorAD2GPI330
Brake SenseAD7GPI43
Speedo OutputPT4PWM131
line pressure sensorAD4EGT227
2WD/4WD switchPE1GPI15
Spare Output1 (LU Feel/Clutch)PT7VB1 (jumper)11
Spare Output2 (Clutch)PA0VB212

In addition there are:

AMPseal Pin
Power In (+12V)1
Power Grounds18, 19, 20
Vref (+5V)28
Sensor Ground17

On the GPIO, the connections are:

On MS-II controllers, the CAN paths are:

The CAN termination resistors are already in place on the MS-II controller and GPIO board.

To wire the 4L60E transmission to the GPIO board, you need to make a number of connections:


  1. For the pressure control (PC) solenoid:
    1. You need a minimum 4.7 Ohm (or higher resistance - up to ~10 Ohms), 10 Watt (or more) resistor (such as Digi-Key 4.7CWBK-ND, $1.67) on the pressure control solenoid wire from the trans connector pin D to the GPIO board's pin 33. This resistor dissipates up to 4 Watts of power at low line pressures (maximum PWM percentages). As a result, the resistor can get hot, so mount it on a heat sink (ideally a metal block) in an area with plenty of air circulation.
    2. In conjunction with that resistor, you will need a 1N4001 recirculation diode placed between pin C and D on the 4L60E connector (the closer to the transmission connector the better). Be careful to orient the diode correctly.
    These two additional external components cut the flyback spikes from the solenoid to manageable levels preventing damage to various GPIO board components and potentially cleaning up external signals such as the VSS.

  2. Any solenoid that is pulse width modulated (including the shift solenoid outputs, TCC, and LUF), if they are PWM'd) require that you put a flyback diode on the solenoid. The illustrated instructions are here: Recirculation Diode Instructions. Install an external diode between that solenoid's voltage supply and the line going to the GPIO board. The banded end of the diode goes to the voltage supply wire, the non-banded end of the diode goes to the line to the GPIO board. Install the diode as close to the solenoid as is convenient. The 1N4001 diode is installed externally to avoid bringing high-voltage noise into the GPIO. 1N4001 diodes are available at virtually any electronics supply shop. Without this external diode in the PWM circuits, you may damage some internal components.

  3. The four resistors for the LEDs can be 330 to 390 Ω, ¼ Watt.

  4. If you want a 'mode selection switch' to force auto mode or enable manual mode, you can do this with a switch and two diodes (1N4001 or equivalent):

    (This circuit only works with 'Shift Button Polarity' = "active low".)

    When the mode switch is closed, auto mode will be used, regardless of what you do with the shift buttons. If the mode switch is open, pushing either the upshift button or downshift button will put you in manual mode (and pushing both OR switching the mode select switch to auto will put you back in auto mode).


The 4L60E uses three types of sensors:

  1. There is an early and a late model of the 4L60E transmission. The difference is the addition of the "Lockup Feel" solenoids (aka. TCC PWM solenoid).
  2. VSS (vehicle speed sensor) on 2WD vehicles is in transmission extension housing, on 4WD vehicles the VSS is in transfer-case.
  3. The ECU also senses a brake switch and turns off the TCC solenoid whenever brakes are applied.
  4. TCC lock-up solenoid is normally only energized in 4th gear, if the transmission temperature is above 250°F it will energize it in 2nd and 3rd as well.
  5. Duty cycle on the Pressure Control solenoid is inversely proportional to the throttle angle (as throttle angle increases, duty is decreased). At idle (minimum throttle), the duty is at max (60%). At WOT (wide open throttle), the duty is at min (0% or off). Note that the PC solenoid takes the place of the Throttle Valve cable on earlier transmissions. In the TunerStudioMS interface, the 0-60% signal has been converted to a 40-100% signal, where 100% means maximum line pressure, and 40% means minimum line pressure. This *should* be more intuitive for the user, hopefully.
  6. All solenoids share common 12V line on pin E (except Pressure Control solenoid, which has its own +12 Volt supply on pin C) and are switched on and off with ground.

Shift PatternSol A (1-2/3-4)
Sol B (2-3)
3-2 Sol
TCC Sol (LU)LockUp Feel***Pressure Control solenoid SolRatio
ReverseONON ON #ON *2.294
NeutralONONON #ON *N/A
1stONONON #ON *3.059
2ndOFFONON ***ON/OFF**ON #ON *1.625
3rdOFFOFFON ***ON/OFF**ON #ON *1.000
4thONOFFON ***ON #ON * 0.696


(Ohms at 68°F)

Solenoid A20 - 4043.0
Solenoid B20 - 4043.0
3-2 Solenoid9 - 1414.1
TCC20 - 4056.9
LU Feel10 - 11.5not known
Pressure Control3.5 - 4.58.1

Pressure Switch Manifold

The pressure switch manifold (PSM) is a multiple switch assembly consisting of 3 normally open (NO) pressure switches and 2 normally closed (N/C) pressure switches.

Fluid from various hydraulic control circuits is fed to this the pressure switch manifold which allows the ECU to determine which gear the shift lever is currently shifted into (not necessarily the actual gear the transmission is in). The switch contacts are normally open and close when fluid pressure causes them to. Depending upon the circuit, the switch may provide a ground path when closed. The table below shows a pin that is grounded by the PSM as a "0", while an open circuit shows a 12 (volts).

GearPin N
Pin R
Pin P
4th (Overdrive)HIGHlowlow
3rd (Drive)HIGHHIGHlow

Case Connector

ASol A (1-2/3-4) Switched GND
BSol B (2-3) Switched GND
E+12 Power
NPressure Switch A
RPressure Switch B
PPressure Switch C
MTemperature Sensor GND
LTemperature Sensor Signal
S3-2 Solenoid Switched GND
DPressure Control Solenoid Switched GND
CPressure Control Solenoid +12V
ULU Feel Solenoid Switched GND
TTCC Solenoid Switched GND

Main Line Pressure Tap

MegaShift has a line pressure sensing/logging function built it. It is Digikey MSP6907-ND for $114. It's a 0.5-4.5 Volt output (accuracy &plusminus;5 psi), and has just a three wire hookup:

  1. 5V from Vref on Ampseal pin #28,
  2. ground, and
  3. signal to Ampseal pin #27.

It has a 1/8 NPT fitting - the same as the transmission port. However, a 90° elbow, or maybe even some tubing, will be required in most installs to keep the sensor away from the transmission tunnel.

4L60E Temperature Sensor Output

°C°F R (Ohms)
-40-40 100544
-28 -21 52426
-16 -10 18580
-4 23 12300
0 32 9379
7 40 7270
19 68 3520
31 86 2232
43 110 1200
55 131 858
67 145 675
79 176 333
91 194 241
103 213 154
115 239 115
127 260 79
139 284 60
151 302 47

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© 2004, 2016 Bruce Bowling and Al Grippo. All rights reserved. MegaSquirt® and MicroSquirt® are registered trademarks. This document is solely for the support of MegaSquirt® boards from Bowling and Grippo.