10 INSTALLATION INSTRUCTIONS
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OPERATIONAL NOTES AND SAFEGUARDS: The following section describes some of the Atomic
TCM’s built-in safeguards, as well as operational notes:
Shifter Position Error: In the event that the Atomic TCM cannot recognize a valid signal from the
transmission’s Range Switch, and translate it to a corresponding shifter position, “ERROR” will be
displayed on the handheld in the SHIFT POS field. If the cause is intermittent, the “ERROR” message
will clear and normal operation will resume. If the error is persistent, the transmission can be operated
in its OEM limp mode (i.e. Park, Reverse, Neutral, and 2nd or 3rd – depending on the transmission
model and OEM limp mode strategy).
Excessive Transmission Fluid Temperature (TFT): If, at any point during operation, the Transmission
Fluid Temperature exceeds 266°F, the Atomic TCM will lock the Torque Converter Clutch (TCC) in
2nd, 3rd, and 4th gear when the Throttle Position Sensor (TPS) is above 2%. The TCC will unlock
when the TPS is less than 2% - regardless of the TFT reading. Normal TCC operation will resume
once the TFT drops below 257°F.
Insufficient Transmission Fluid Temperature (TFT): Overdrive (OD) engagement is prohibited until
the TFT reaches 47°F and Torque Converter Clutch (TCC) lockup is prohibited until the TFT reaches
84°F.
Engine Braking in Manual Mode: The transmissions supported by the Atomic TCM typically do not
provide engine braking when operating with the shifter in the Overdrive (OD) position. In order to take
advantage of engine braking, it is necessary to move the shifter position to Drive (D) or OD Cancel
(Ford only). When operating the Atomic TCM in Manual Mode, DO NOT do so with the expectation
of engine braking occurring with the shifter in Overdrive (OD). All supported transmissions should
provide engine braking with the shifter in the Manual 2 or Manual 1 position.
Low Speed Operation in Manual Mode: When operating in Manual Mode, thresholds are in place to
provide automatic downshifts, and prevent premature upshifts, at low vehicle speeds. This prevents
the possibility of pulling away from a stop in too high a gear, or upshifting through the gears too quickly
and loading the engine excessively. The thresholds are summarized in the table below:
Gear Transition Vehicle Speed (MPH)
1-2 / 2-1 5
2-3 / 3-2 10
3-4 / 4/3 15
Alternately, you do not necessarily have to worry about Manual
Mode downshifting when coming to a stop. The Atomic TCM
ensures a subsequent 1st gear start.
Engine Overrev Protection in 1st Gear: Whether you are
in Manual 1 and forget to upshift, or attempting a high-speed
downshift to first gear (Auto or Manual Mode), the Atomic TCM
will not allow the engine speed to exceed the value entered for
MAX SHIFT RPM (see Initial Setup menu). Based on the rear
gear ratio, tire height, and maximum engine speed entered
during the Initial Setup phase, the Atomic TCM automatically
computes the corresponding maximum vehicle speed allowed
in 1st gear. If MAX SHIFT RPM is exceeded in Manual 1, the
Atomic TCM will force an upshift to 2nd gear. Conversely, high-
speed 2-1 downshifts are prohibited until the vehicle speed
has dropped below a value that will not cause MAX SHIFT
RPM to be exceeded.
MSD 2760 – Atomic Transmission Controller – Diagnostics Summary
Figure 13
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