MegaShift™ 4L60E Wiring

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

Inputs to GPIO
Pin	Function
L	Temperature Sensor Signal
M	Temperature Sensor GND
N	Pressure Switch A (aka. Pin A)
R	Pressure Switch B (aka. Pin B)
P	Pressure Switch C (aka. Pin C)
n/a	2WD/4WD Input (ground for 4WD)
n/a	Vehicle Speed Sensor (VSS) - has its own 2-pin connector

Outputs from GPIO
Pin	Function	Control	Limits
A	Sol A (1-2/3-4) Switched GND	On/Off	20-40 Ohms (0.75 Amps Max.)
B	Sol B (2-3) Switched GND	On/Off	20-40 Ohms (0.75 Amps Max.)
C	Pressure Control Solenoid High	Power (nominal +12V)	Switched 12V from harness
D	Pressure Control Switched GND	PWM (293Hz)	0 to 60% (3.5 - 4.6 Ohms at 20°C, 1.1 Amps Max.)
E	+12 Volt Power	High (nominal +12V)	Switched 12V from harness
U	Lock-Up Feel Solenoid Switched GND not always used
S	3-2 Sol Switched GND	PWM (50Hz)	(9-14 Ohms at 20°C)
T	Torque Converter Clutch Solenoid Switched GND	On/Off	20-40 Ohms (1.5 Amps Max.)

The wiring inside the 4L60E transmission looks like this:

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

Function	Port	Circuit	AMPseal Pin
Sol A	PE4	VB3	23
Sol B	PM2	VB4	35
Sol32	PT1	PWM4	34
PC	PT2	PWM3	33
TCC	PT3	PWM2	32
LED1	PM4	GPO1	10
LED2	PM3	GPO2	7
LED3	PM5	GPO3	8
LED4	PB4	GPO4	9
switchA	AD0	EGT4 (jumper)	26
switchB	AD1	GPI2	6
switchC	AD3	EGT3	25
Paddle UP	PT6	VR2	15
Paddle DOWN	AD6	GPI5	4
VSS	PT0	VR1	2
Temp Sensor	AD2	GPI3	30
Brake Sense	AD7	GPI4	3
Speedo Output	PT4	PWM1	31
non-CAN MAP/TPS/MAF	AD5	EGT1	24
line pressure sensor	AD4	EGT2	27
2WD/4WD switch	PE1	GPI1	5
Spare Output1 (LU Feel/Clutch)	PT7	VB1 (jumper)	11
Spare Output2 (Clutch)	PA0	VB2	12

In addition there are:

Function	AMPseal Pin
Power In (+12V)	1
Power Grounds	18, 19, 20
Vref (+5V)	28
Sensor Ground	17
CANH	13
CANL	16

On the GPIO, the connections are:

• CANH: Ampseal connector pin 13,
• CANL: Ampseal connector pin 16.

On MS-II controllers, the CAN paths are:

• CANH: CPU pin PM0 (#45) → 40-pin socket pin 6 → JS6 jumper to SPR1/CANH → DB37 pin 3,
• CANL: CPU pin PM1 (#44) → 40-pin socket pin 11 → JS8 jumper to SPR2/CANL → DB37 pin 4.

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

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

Note that you need a 4.7 Ohm, 5 Watt (or more) resistor (such as Digi-Key 4.7W-5-ND, 34¢) on the pressure control solenoid wire from the trans connector pin D to the GPIO board's pin 33, and a 1N4001 diode placed between pin C and D on the 4L60E connector (the closer to the transmission connector the better). These cut the flyback spikes from the solenoid to manageable levels.

The four resistors for the LEDs can be 330 to 390 Ohms, 1/4 Watt.

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).

If you are looking for a 4L60E harness connector, try a scrap yard, or here: www.currentperformance.com/Connectors/LS1_LS6.html

Sensors:

The 4L60E uses three types of sensors:

• Temperature Sensor, used to determine TCC lock-up,
• 3 Pressure Switches (not that these are sometimes called 'transmission pressure switches, TPS, but they should not be confused with the Throttle Position Sensor), used to determine the currently selected gear (i.e., the shift lever position),
• Vehicle Speed Sensor (variable reluctance [VR] type), used for a number of criteria.

1. There is an early and a late model of the 4L60E transmission. The difference is the addition of the "Lockup Feel" solenoids.
2. VSS (vehicle speed sensor) on 2WD vehicles is in transmission extension housing, on 4WD vehicles the VSS is in transfer-case. The VSS signal is sensitive to low levels of electrical noise. This can disrupt the signal, and make the speedometer misbehave. Since speed is a critical input to your MShift™ controller, you need to get as clean a VSS signal as you can. As a minimum, you should at least use a twisted pair of wires to connect the VSS wires to Ampseal pins 2 and 17. There are many tips on how to clean up a VSS signal on this page.
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 TunerStudio 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.

• * The Pressure Control solenoid controls main line pressure, pulsed at 0-60% duty cycles at 293Hz. There is no cleaning pulse (dither) every 10 seconds on this transmission (unlike the 4L80E). The pressure control solenoid MUST have a recirculation diode installed between its 12V supply and the MShift™ wire controlling it (as does ANY device that is PWM by your MShift™ controller). The diode goes with the banded end towards the 12V supply, and the non-banded end towards pin T on the transmission. It should be placed as close to the transmission as convenient. The recirculation diode shunts high voltage spikes away from the MShift™ controller, thus reducing electrical noise and increasing component reliability.
• ** The TCC is pulse width modulated. It appears to be 32 Hz, with duty cycle varied. Maximum current should not exceed 1.5 AMPS. The TCC solenoid MUST have a recirculation diode installed between its 12V supply and the MShift™ wire controlling it (as does ANY device that is PWM by your MShift™ controller). The diode goes with the banded end towards the 12V supply, and the non-banded end towards pin D on the transmission. It should be placed as close to the transmission as convenient. The recirculation diode shunts high voltage spikes away from the MShift™ controller, thus reducing electrical noise and increasing component reliability.
• *** The 3-2 Sol is pulsed at 50Hz, 0% duty in 1st, 90% duty in all other gears. During a 3-2 downshift, the duty is decreased and this duty is related to the vehicle speed; lower speed, lower duty.
• # The Lock-Up Feel solenoid was probably put in high end Cadillacs for seamless shifting.

Solenoids:

Solenoid	Resistance (Ohms)	Typical Inductance (milliHenries)
Solenoid A	20 - 40	43.0
Solenoid B	20 - 40	43.0
3-2	9 - 14	14.1
TCC	20 - 40	56.9
LU Feel	not known	not known
Pressure Control	3.5 - 4.5	8.1

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).

Case Connector

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