MegaShift™ 41te Wiring

This page provides information on how the 41te (aka. A604) automatic transmission from Chrysler operates with the MegaShift™ controller, as well as the TunerStudioMS settings needed to configure the controller. Note that this transmission has been in service since 1989, and has undergone many changes. Do your homework (a factory service manual for your model and year is usually the best place to start) to be sure the settings you choose are right for your transmission.

The 41te is a 4-speed (with overdrive), electronically controlled transmission. "41te" stands for:

• 4 forward ratios,
• load range 1,
• transverse mount,
• electronic control.

The 41te has ratios:

Gear	Ratio
1	2.84
2	1.57
3	1.00
4 (OD)	0.69
Reverse	2.21

The axle ratio can be a number of values. These typically relate to the accompanying engine size:

Engine Displacement	Axle Ratio
2.0L	4.08
2.4L/2.5L	3.91
3.0L/3.3L	3.60
3.8L	3.45

The 41te has 2 speed sensors, one on the output and one on the input shaft. This can be useful to see if the clutch packs are slipping and to check converter-lockup slippage. The output shaft sensor has 22 teeth. The input shaft is believed to have ~54 teeth.

Wiring

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

Outputs

Solenoid resistance is ~2.5 Ohms (depending on temperature and other test conditions). They are all pulse width modulated. The frequency for the solenoids is 1.96 kHz. The factory pulse width modulation percent is 38%, except in 3rd/4th, where it is 30% (plus refresh of 8 milliseconds every 50 milliseconds).

For the Shift Output Patterns, these are:

Outputs from GPIO
Gear↓	Output 1 Low/Reverse Solenoid	Output 2 2/4 Solenoid	Output 3 Underdrive Solenoid	Output 4 Overdrive Solenoid
Park	ON	ON	ON	off
Neutral	ON	ON	ON	off
Reverse	ON	ON	ON	off
1st	ON	ON	off	off
2nd	off	off	off	off
3rd	off	ON	off	ON
4th (OD)	off	off	ON	ON

CAN Connections

On the GPIO, the connections are:

• CANH: Ampseal connector pin 13, connect to DB37 pin3
• CANL: Ampseal connector pin 16, connect to DB37 pin 4

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™ and GPIO.

Shift Mode Switch

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).

Range Switches

The factory shifters use a 'P R N OD 3 L' pattern. 'L' is second and there is no option to manually select 1st gear. However, there is a extra detent for first gear in the valve body that the factory doesn't use. So you can use that if you want to by either:

• modifying the the factory shifter for one extra detent, or
• running a aftermarket shifter.

Just a note, the valve body makes no changes at all in any forward gear, when you move the shifter all that gets changed is the outputs on the range sensor. There are no hydraulic changes at all.

The range sensor has a output for backup lights and your safety switch as well as a temp sensor.

Torque Converter Clutch Control

Converter lockup is controlled by the Low/Reverse solenoid, once the trans shifts to 2nd gear a spool valve is moved that allows the lockup to work with the L/R solenoid. The TCC is controlled by the the L/R solenoid, once the trans shifts into 2nd gear. So we only have the hydraulic possibility of lockup in 2nd, 3rd and 4th gear.

For TCC wiring, you connect the 'Low/Reverse' solenoid to *both* Output 1 (Ampseal #23) and the TCC pin (Ampseal #32).

Line Pressure

Line pressure is handled by a internal pressure valve. The MShift™ controller doesn't control the transmission's line pressure at all. You can use the pressure control output for other uses that depend on load and/or speed (such as a boost controller).

You can still log the line pressure. You could use a MSP6907-ND for $114 from Digi-Key. It's a 0.5-4.5 Volt output (accuracy ±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.

You could use something similar that will give a 0 to 5 Volt output. You can change the relationship of the voltage to pressure to match different sensors.

41te Temperature Sensor Output

The 41te temperature sender (which is assumed to have the same response curve as the common 1985+ Chrysler temperature sensors) is:

TunerStudioMS Settings:

Here is a list of the settings you will need to change in TunerStudio:

1. Vehicle Speed Sensor: The output shaft VSS sensor reads 22 teeth per revolution. Set 'Number of VSS Teeth': 22.

2. Input Shaft Speed Sensor: Enable the Input Shaft Speed Sensor by setting:
   • 'ISS/Tach Input Usage': Input Shaft Speed

   Then set the number of input shaft teeth under:

   • 'Pulses/Revolution': 54

   54 might not be the correct number. You may need to enter other values. If you do not know the correct number for your transmission, you may have to experiment until the engine rpm matches the input shaft speed at low loads during cruise conditions.

3. 'Temperature Sensor': You will need to recalibrate the temperature sensor, which has the standard General Motors response curve as a default. You recalibrate the curve using the ''Tools/Calibrate Thermistor Table' function:

   Parameter	Value
   Sensor Table	Coolant Sensor
   Bias Resistor	2490 Ω

   Temperature (°F)	Resistance (Ω)
   41.9	24500
   86.9	8100
   190.94	850

   Select the values then click 'Write to Controller'. Allow time for the burn to complete - do not shut off the controller while the burn is active, or the values will be corrupted.

4. Gear Ratios: You need to set the 41te gear ratios under 'General Settings/Gear Ratios':

   Gear	41te Ratio
   1	2.84
   2	1.57
   3	1.00
   4 (OD)	0.69
   Reverse	2.21

   The axle ratio can be a number of values. These most commonly relate to the accompanying engine size:

   Engine Displacement	Axle Ratio
   2.0L	4.10
   2.4L	3.90
   3.0L/3.3L	3.60
   3.8L	3.45

5. PWM Parameters: With the MShift™ controller, we use a PWM% of 50%, with refresh added on top of that to ensure quick shifts.

   You set up the PWM parameters under 'General Settings/Solenoid PWM Setup'. Set:

   • 'Output3 PWM Period': 0.510 milliseconds
   • 'Output3 DC when ON': 50%
   • 'Output1/2/4 ON Period': 0.256 milliseconds
   • 'Output1/2/4 OFF Period': 0.256 milliseconds

   The setting above will give a 1.96 kHz PWM (period = 1/1960 = 0.51 milliseconds), with 50% duty cycle (plus refresh) for all the solenoids.

   You *might* be able to get away with less PWM (as low as 25%) for lower current consumption and less heat in the solenoids. If you want to try that, set:

   • 'Output3 PWM Period': 0.510 milliseconds
   • 'Output3 DC when ON': 33%
   • 'Output1/2/4 ON Period': 0.128 milliseconds
   • 'Output1/2/4 OFF Period': 0.384 milliseconds

   These settings (above) will give a 1.96 kHz PWM (period = 1/1960 = 0.51 milliseconds), with 25% to 33% duty cycle (plus refresh) for all the solenoids.

   Either way, you need to set up the refresh cycles for the PWM. Do that under 'PWM Refresh and Dithering' set:

   • PWM Refresh Interval: 50 milliseconds
   • PWM Refresh Duration: 8 milliseconds

   You do not need to changed the 'Dither' settings, these are not used (since the pressure control output isn't used).

   You also need to enable PWM on the TCC circuit:

   • TCC PWM Mode: Use PWM for TCC
   • TCC PWM Period: 0.510 milliseconds
   • PWM% when TCC Unlocked: 0%
   • PWM% when TCC Locked: 50%

   Since you are enabling PWM on Output1, Output2, Output3, and Output4, and TCC, you MUST install an external recirculation diode (such as a 1N4001) between each 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.

6. Range Switches: You need to set the gear selector range switch input to match the transmission. First, enable the 4th input, do this under 'Standard Inputs/Outputs Configuration', set:
   • GPI1/Amp5 INPUT Usage: Additional lever input

   Then under 'Shift Input Patterns' set:

   Gear	Input 1 (T1)	Input 2 (T3)	Input 3 (T41)	Input 4 (T42)
   Park	HIGH	low	low	low
   Neutral	low	HIGH	low	low
   Reverse	HIGH	HIGH	HIGH	low
   1st	low	low	HIGH	HIGH
   2nd	low	low	HIGH	low
   3rd (Drive)	HIGH	low	HIGH	HIGH
   4th (Overdrive)	low	HIGH	HIGH	HIGH

7. Shift Solenoid Patterns: For the shift solenids, first enable the 4th output under Spare Port 2 (VB2/PA0). Set:
   • SparePort2/Shift Solenoid: Shift Solenoid

   Then set the Shift Output Patterns:

   Outputs from GPIO
   Gear↓	Output 1 Low/Reverse Solenoid	Output 2 2/4 Solenoid	Output 3 Underdrive Solenoid	Output 4 Overdrive Solenoid
   Park	ON	ON	ON	off
   Neutral	ON	ON	ON	off
   Reverse	ON	ON	ON	off
   1st	ON	ON	off	off
   2nd	off	off	off	off
   3rd	off	ON	off	ON
   4th (OD)	off	off	ON	ON