Description:
The Top Gear Ratio parameter refers to the Eaton Top 2 Gear Ratios that are used by the ECM to decide when to energize the Shift and Lockout solenoid outputs (required for the Eaton Top 2 feature) when shifting between the top two gears in vehicles equipped with Eaton Top 2 transmissions. These parameters are Top Gear Ratio, Top Gear Minus One Ratio, and Top Gear Minus Two Ratio. These parameters have no effect if the Transmission Style parameter is not programmed to Eaton Top 2, however they must be correctly programmed if it is programmed to Eaton Top 2.
Top Gear Ratio
This ratio identifies the highest gear ratio for an Eaton Top 2 Transmission. The programmable range is shown in the table below. Note that for Gear Fast Run Slow (GFRS) ratings the default value should be 0.731.
Top Gear Minus One Ratio
This ratio identifies the second highest gear ratio for an Eaton Top 2 Transmission. The programmable range is shown in the table below. Note that for Gear Fast Run Slow (GFRS) ratings, the default value should be 0.856.
Top Gear Minus Two Ratio
This ratio identifies the third highest gear ratio for an Eaton Top 2 Transmission. The programmable range is shown in the table below. Note that for Gear Fast Run Slow (GFRS) ratings, the default value should be 1.00.
Available:
C-10, C-12, C-15, C-16, C11, C13, C15 heavy duty engines
Range:
Note: The XX appearing in the transmission model number refers to (x) 100=Nominal Torque Capacity. For example, RTLO-14613A has a Nominal Torque capacity of 14 (x) 100 or 1400 lb ft. The transmission model designation and other transmission identification information are stamped on the transmission tag on the lower left side near the front of the transmission.
Advantages:
When properly programmed, these parameters allow the Eaton Top 2 Transmission to effectively control automatic shifting in the top 2 gears.
Disadvantages:
None
Recommendations:
These parameters must be precisely programmed to three decimal places to ensure proper operation of the Eaton Top 2 transmission and the engine in the top 2 gears. Not programming this parameter precisely may result in a 253-11 Check Transmission Customer Parameters diagnostic code.