NOTE
If clearing a code while locked in a «D» (Drive) or «R» (Reverse) position (fail-to-range), the transmission
will still be in «D» (Drive) or «R» (Reverse) when the clearing procedure is completed. «N» (Neutral) must
be manually selected.
DIAGNOSTIC TROUBLE CODE RESPONSE
The electronic control system is programmed to inform the operator of a problem with the transmission system
via the CHECK light and shift selector display while it automatically takes action to protect the operator,
vehicle, and transmission. When the Transmission Control Module (TCM) flags a Diagnostic Trouble Code
(DTC) as active, the TCM may take a combination of diagnostic responses as listed in the table below.
RESPONSE CATEGORY ACTIONS TAKEN
DNS - Do Not Shift
Release lock up (LU) clutch and inhibit lock up operation.
Inhibit shifts from the current attained range.
Turn on the CHECK light.
Display the current attained range in the MONITOR window of the shift
selector.
Blank the SELECT window of the shift selector.
Ignore any range selection inputs from the shift selector.
SOL OFF - Solenoid OFF
All solenoids are commanded off, resulting in hydraulic default operation
of the transmission – PCS1 & PCS2 are on hydraulically when off
electrically.
RPR - Return to Previous
Range
When the speed sensor ratio or PS1 tests do not pass, the TCM
commands the same range as commanded before the shift.
NNC - Neutral No Clutches
When certain speed sensor ratio or PS1 tests do not pass, the TCM
commands a neutral condition with no clutches applied.
DNA - Do Not Adapt The TCM stops adaptive shift control while the code is active.
PA-1652 Operator's Manual H3-45 Coach
Allison Transmission Other Features C-9
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