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4LHD/4LHDX Application Manual
Powertrain Control Solutions
REV 1.1
Water/Dust Intrusion
PCS and the customer must agree upon applicable water and dust intrusion specifications, test levels, and report formats.
More stringent requirements will increase TCM costs due to enclosure and connector sealing requirements.
Electromagnetic Compatibility (EMC)
PCS and the customer must agree upon applicable EMC specifications, PCS shall be responsible for TCM testing to
applicable EMC specifications. The customer shall be responsible for vehicle-level testing and certification.
Electronic Controller System Summary
Selecting an appropriate TCM solution requires several defining characteristics to be agreed between PCS and the
customer. Here is an example summary chart of plausible defining characteristic combinations:
Control Algorithms
The TCM uses an electronic transmission control algorithm to monitor and control the transmission. This algorithm is
actually a combination of many algorithms.
Shift Point Control
PCS transmissions select proper operating gear based upon driver input, vehicle dynamics, engine operation, and vehicle
self-diagnostic operation. The TCM will operate the shift control solenoids to command the selected gear.
Shift Quality Control
PCS automatic transmissions provide smooth and precise ratio transitions between gears. During steady-state operation,
control algorithms optimize operation to increase vehicle fuel economy while protecting transmission durability. The TCM
will operate the line pressure control solenoid to ensure smooth ratio transitions and to maximize fuel economy.
Torque Converter Clutch Control
The Torque Converter Clutch is used to eliminate slip across the transmission torque converter. In some applications, a
continuously-slipping converter clutch may be available to improve vehicle performance. The TCM will operate the Torque
Converter Clutch solenoid(s) to maximize fuel economy and vehicle performance.
Abuse Protection
The automatic transmission control system will work to minimize torque disturbances shifts and to manage sudden torque
when abusive or excessive torque is being transmitted through the transmission. This interface is usually achieved by
software interfaces in TCM that will disable certain functions if they are determined abusive maneuvers.
Diagnostic System
PCS TCMs provide self-diagnostic testing to detect failures and degradation within the TCM and transmission hardware.
All PCS automatic transmissions will support the latest On-Board Diagnostic (OBD) legislation and J1939.
Characteristic
Example TCM
Mounting Location
Transmisison
Operating Temperature
-40°C to 105°C
Storage Temperature
-40°C to 125°C
Water Intrusion
Sealed to 3 foot submersion
EMC Specifications
GM 9100
Size and Weight
H: 105 mm; W: 185 mm; D: 33 mm; Mass: 2000 gr.
Vehicle Electrical Interface
SAE J1850/GM Class 2
Service Tool Interface
SAE J1850/GM Class 2
Diagnostic Specifications
CARB OBDII