Transmission limp home mode – Ram Trucks 2014 Chassis Cab Commercial - Diesel Supplement User Manual

Page 230

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During cold temperatures, transmission operation may

be modified depending on engine and transmission

temperature as well as vehicle speed. This feature im-

proves warm up time of the engine and transmission to

achieve maximum efficiency. Engagement of the torque

converter clutch is inhibited until the transmission fluid

is warm (refer to the “Note” under “Torque Converter

Clutch” in this section). On Pickup models with 68RFE

transmission, top overdrive gear is also inhibited until

the transmission fluid is warm, and during extremely

cold temperatures (-16°F [-27°C] or below), operation

may briefly be limited to first and direct gears only. On

trucks with AS69RC transmission, fifth and sixth gears

may be inhibited briefly on cold starts below 41°F (5°C),

and during very cold temperatures (-4°F [-20°C] or

below), operation may briefly be limited to third gear

only. During this condition, the ability of the vehicle to

accelerate under heavily loaded conditions may be re-

duced. In all cases, normal operation will resume once

the transmission temperature has risen to a suitable level.

Transmission Limp Home Mode
Transmission function is monitored electronically for

abnormal conditions. If a condition is detected that could

result in transmission damage, Transmission Limp Home

Mode is activated. In this mode, the transmission remains

in fourth gear (for 68RFE transmission) or third gear (for

AS69RC transmission) regardless of which forward gear

is selected. If an AS69RC-equipped truck enters Limp

Home Mode at highway speeds, it will initially engage

fifth gear, until the vehicle slows to a speed where third

gear can be engaged. PARK, REVERSE, and NEUTRAL

will continue to operate. The Malfunction Indicator Light

(MIL) may be illuminated. Limp Home Mode allows the

vehicle to be driven to an authorized dealer for service

without damaging the transmission.

228 STARTING AND OPERATING

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