Use this procedure under the following situation:
The multitorque software is suspected of operating incorrectly. Access the Instantaneous Screen if the vehicle is equipped with the (CAT ID) Driver Information Display. This screen will show the status of the multitorque feature in order to determine if the multitorque feature is activating.
Background of the multitorque feature
The multitorque feature is an optional feature. This feature requires unique software. The multitorque feature provides an otherwise standard engine with two different torque curves. The torque curve for the lower gears functions as a standard engine. The torque curve for the top gears provides additional torque. The transmission ratio determines the top gears. In the top gears, the engine provides additional torque. This additional torque is typically 136 N·m (100 lb ft).
The ECM determines when the vehicle is in the top gears by sensing the ratio of engine speed to vehicle speed. The engine will operate with the higher torque curve if the ratio of engine speed to vehicle speed is within the specified range.
The engine ratings are based on the trip point. Additional torque is made available at the trip points. The three options are listed below.
- MT-4 ratio is 71.5 rpm/mph & below (Top 4 Gears)
- MT-2 ratio is 37.6 rpm/mph & below (Top 2 Gears)
- MT-1 ratio is 27.9 rpm/mph & below (Top 1 Gear)
With OCT99 and newer software, the "Multitorque Ratio" parameter was added. This allows the selection of the desired ratio turn on trip point (MT-1, MT-2, or MT-4). "Multitorque Ratio" is used rather than requiring three different ratings that are based only on the different ratio trip points. With older software, the engine rating determined the specific ratio that was used for the vehicle application.
The multitorque feature differs from the PTO torque limit. The PTO torque limit requires a torque limit switch. Multitorque software provides a second torque curve. The engine will not exceed the PTO torque limit. The ECM essentially removes the top of the torque curve at the programmed PTO torque limit. The PTO torque limit is used only for temporary protection of equipment.
Test Step 1. Repair all Diagnostic Codes and Other Problems
- Make sure that there are no active diagnostic codes and make sure that there are no logged diagnostic codes that affect engine performance.
- Refer to the procedure that best describes the symptom if there are any other complaints or symptoms. Refer to Troubleshooting for troubleshooting information on specific symptoms, or the relationship between diagnostic codes and possible performance related complaints.
Expected Result:
No other detectable problems exist.
Results:
- OK - Proceed to Test Step 2.
- Not OK - Repair any other problems, as required. Proceed to Test Step 2.
Test Step 2. Verify that the Software is Installed
- Connect the Caterpillar Electronic Technician (ET) to the cab data link connector.
- Turn the ignition key switch to the ON position.
Expected Result:
The rating type in the customer specified parameters indicates "Multitorque".
Results:
- OK - Proceed to Test Step 3.
- Not OK - The engine is not equipped with the multitorque feature.STOP
Test Step 3. Verify a Change in the Rated Fuel Limit
- Put the vehicle on a dynamometer or take the vehicle for a road test.
- Operate the vehicle in the lower gears at an approximate engine speed of 1200 rpm. A load on the engine is not required.
- Read the "Rated Fuel Limit" and record the "Rated Fuel Limit" from the status screen on ET.
- Operate the vehicle in the top gear at 1200 rpm. Read the "Rated Fuel Limit" and record the "Rated Fuel Limit".
Expected Result:
The "Rated Fuel Limit" in the top gear is greater than the "Rated Fuel Limit" in the lower gears.
Results:
- OK - The multitorque feature is operating correctly.STOP
- Not OK -
Repair: Verify that the vehicle specifications are compatible with the multitorque feature. The ratio of engine speed to vehicle speed should be less than 71.5 in top gear. The ratio of engine speed to vehicle speed should be less than 44.7 when metric vehicle speed is used.With OCT99 and newer software, verify that the "Multitorque Ratio" parameter is programmed to the correct setting.Verify that the repair eliminates the problem.
STOP