Transmissions

18.0 Transmissions

Caterpillar C7 and C9 engines can be connected to a variety of transmissions.The following table lists the available transmission style options and the required switch inputs for each option.Correct programming and switch wiring is required to provide proper cruise control, PTO, and Fast Idle operation.

*This switch input can be a J1939 message from the J1939 Instrument Cluster, J1939 Cab Controller, orJ1939Body Controller. **This switch input can be a J1939 message from the transmission.

18.1 Transmissions Equipped with J1939 Communication

The C7 and C9 engines can communicate with transmissions over the SAE J1939 data link.The engine will respond to transmission requests for speed and torque limiting.Transmissions can request that the engine engage the auxiliary brake to assist in shifting or prevent shift cycling.The transmission may request that the engine’s auxiliary brake be disengaged to prevent damage to torque converter.

18.2 Recommendations for the Exhaust Brake

The transmission torque converter cannot tolerate engine auxiliary brake operation if the torque converter clutch isnot engaged.If the engine is equipped with an Exhaust Brake the Engine Exhaust Brake Switch parameter must be programmed to J1/P1:16 or one of the J1939 sourced inputs.A physical switch does not have to be installed as an open circuit is the same as an open switch.

18.3 Recommendations for Cooling Fan

The cooling fan causes engine loading that may interfere with transmission shifting.The J1939 broadcast for engine load is adjusted to compensate for cooling fan loading.Caterpillar recommends the following: 1) ECM controlled cooling fan 2) Air Conditioning input for fan control 3) If used, the manual fan override switch must be an input to the ECM

Transmission Switch Usage

Style Parameter Setting Service Service Clutch Transmission Brake #1 Brake # 2 J1/P1:22* Neutral J1/P1:45 * J1/P1:64 J1/P1:62**

Manual Option 1 X – X –Manual Option 2 X X X –Universal X X X X Automatic Option 1 X – – –Automatic Option 2 X X – –Automatic Option 3 X X – X Automatic Option 4 X – – X AT/MT/HT Option 1 X – – –AT/MT/HT Option 2 X – – –AT/MT/HT Option 3 X – – X AT/MT/HT Option 4 X – – X

18.4 Allison WT Series

The Allison WT requires connection to the SAE J1587/J1708 or SAE J1939 data link to communicate to the C7orC9 ECM.

OEM provided and installed components required: 1) SAE J1587 or SAE J1939 Data link connection to the Allison transmission control. 2) If the Transmission Style parameter is programmed to Automatic Option 2 or Automatic Option 3, connect

Input#13 to Brake Switch #2. 3) If the Transmission Style parameter is programmed to Automatic Option 3, Automatic Option 4 or Universal, connect the Neutral switch to Input #12 or the SAE J1939 data link. Customer Parameter programming required: 1) Transmission Style parameter programmed to Automatic Option 1, Automatic Option 2, Automatic Option 3, orAutomatic Option 4. 2) Driveline Data Link parameter programmed to J1939 3) Transmission Neutral Switch parameter programmed to J1/P1:62 or J1939 (Transmission Style dependent)

18.5 Allison 1000 & 2000 Series

The Allison 1000 and 2000 Series transmissions REQUIRE connection to the J1939 data link to communicate tothe C7 or C9 ECM.

OEM provided and installed components required: 1) SAE J1587 or SAE J1939 Data link connection to the Allison transmission control. 2) If the Transmission Style parameter is programmed to Automatic Option 2 or Automatic Option 3, connect Input #13 to Brake Switch #2. 3) If the Transmission Style parameter is programmed to Automatic Option 3 or Automatic Option 4, connect the

Neutral switch to Input #12 or the SAE J1939 data link. Customer Parameter programming required: 1) Transmission Style parameter programmed to Automatic Option 1, Automatic Option 2, Automatic Option 3, orAutomatic Option 4. 2) Driveline Data Link parameter programmed to J1939 3) Transmission Neutral Switch parameter programmed to J1/P1:62 or J1939

18.6 Allison AT/MT/HT Transmissions

The Allison AT/MT/HT (non-electronic) transmissions require an input from the ECM to regulate transmission shifting.The ECM does not control the transmission shift schedule.The ECM monitors accelerator pedal position, engine speed, load, and cruise control status to determine if the transmission should use “closed throttle”or “full throttle”shift modulation. Programming the Transmission Style parameter to AT/MT/HT Option 1, AT/MT/HT Option 2, AT/MT/HT Option 3, orAT/MT/HT Option 4 activates 7J1/P1:20 to control a shift interface relay connected to the transmission. Thisoutput does not control an Allison AT/MT/HT transmission with an ATEC control. The Shift Modulation setting is selectable by programming the AT/MT/HT Part Throttle Shift Speed parameter. Three different modulation settings are available:Low (80% ON/65% OFF), Medium (70% ON/55% OFF), and High(60% ON/45% OFF).The High setting is the default setting, which will cause the transmission to remain in alower gear longer (higher engine speed before shift occurs).The Medium setting is a compromise between the Default and the High setting. NOTE:Contact Allison Transmissions regarding recommended settings of this parameter for your application.

OEM provided and installed components required: 1) Shift Interface Relay. 2) J1/P1:20 connected to the Shift Interface Relay. 3) Allison AT/MT/HT mechanical transmission with shift modulator. If the Transmission Style parameter is programmed to AT/MT/HT Option 2 or AT/MT/HT Option 3, connect J1/P1:64 to Service Brake Pedal Position Switch #2. If the Transmission Style parameter is programmed to AT/MT/HT Option 3 or AT/MT/HT Option 4, connect J1/P1:62 to the Transmission Neutral Switch.

Customer Parameter programming required: 1) Transmission Style programmed to AT/MT/HT Option 1, AT/MT/HT Option 2, AT/MT/HT Option 3, orAT/MT/HTOption 4. 2) AT/MT/HT Part Throttle Shift Speed programmed to desired setting – Low, Medium or High.

18.7 Allison AT/MT/HT Shift Interface Relay Operation

The AT/MT/HT Relay Circuit is provided by the ECM to indicate when the transmission should utilize closed throttle modulation or full throttle modulation.This allows the transmission to select Economy Mode or Performance mode. Operation of the relay is different depending upon whether cruise control is active or inactive. NOTE: Minimum ON and OFF time of the driver is based on vehicle speed changes.

Wiring Diagram 31

18.7.1 Shift Relay Operation with Cruise Control or Vehicle Speed Limiting Not Active

If enabled, the AT/MT/HT Relay is disabled under any of the following conditions: 1) Engine is not running. 2) Accelerator Pedal Position less than he AT/MT/HT Part Throttle Shift Speed setting:Low = 65%, Medium = 55%, or High = 45% (default). If disabled, the AT/MT/HT Relay is enabled when all of the following conditions are met: 1) Engine is running. 2) Accelerator Pedal Position greater than the AT/MT/HT Part Throttle Shift Speed setting:Low = 80%,

Medium=70%, or High = 60% (default).

C ALLISON ELECTRIC MODULATOR M ALLISON AT/MT RELAY +IGNITION

ECM

G839-BU 20 OUTPUT #7 J1 P1

18.7.2 Shift Relay Operation with Cruise Control or Vehicle Speed Limiting Active

If enabled, the AT/MT/HT Relay is disabled when all of the following conditions are met: 1) Vehicle speed is greater than or within 2 mph (3.2 km/h) of the Cruise Set Speed or the Vehicle Speed Limit. 2) Unfiltered Load factor is < 75%. 3) Engine Speed > 2000 rpm. If disabled, the AT/MT/HT Relay is enabled when the following conditions are met: 1) Filtered Load factor is > 98% 2) Vehicle Speed is more than 4 mph below the Cruise set speed.