BMW Transmission FailSafe Emergency Programs Explained

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Last Updated on Tuesday Feb 06, 2018

Problem

BMW transmission may get stuck in limp mode. When this happens it is called failsafe mode which is designed to protect the BMW transmission from being damaged. Often turning off the ignition and restarting the car will solve the problem. Unless a more serious problem exists and the BMW transmission goes into Emergency Mode 3 or 4.

Solution

Emergency Programs
There are a total of four emergency operation programs stored in the MS S52 control module.
The MS S52 control module will activate one of these programs depending on which
fault is present or what the failed component is. With any fault that is relevant to the EDR
system, the engine’s output torque will be reduced to provide limited driveability of the vehicle.

EMERGENCY PROGRAM #1. - Engine operation with PWG input. The engine’s output
torque is limited to 480 Nm. This program will set with faults in one PWG sensor input or
one throttle valve feedback input.

EMERGENCY PROGRAM #2. - Engine operation through the idle valve actuator. The
engine’s output torque is limited to 300 Nm and the vehicle’s speed to 70 MPH. With program
#2, the throttle valves are shut down and only the idle valve is used for engine operation.
This program will set with a fault in one air mass sensor input and one PWG sensor
input.

EMERGENCY PROGRAM #3. - Engine operation with jammed throttle valves. The engine’s
output torque is limited to 300 Nm and the speed is limited to 35 MPH. This is carried out
through ignition and injection intervention if the MS S52 senses that the throttle valves are
jammed or stuck and cannot be closed by applying power through the EDR actuator.

EMERGENCY PROGRAM #4. - Engine operation with a control module internal fault. The
engine’s output torque is limited to 250 NM and the speed is limited to 35 MPH. Depending
on the degree of the fault, the control module with the dual processors will enable limited
engine operation.

Category
Transmission