Allison Transmission 4700

•enginewatertemperatureascommunicatedtotheTCMwithanengine
coolantsensororviaanSAEJ1939datalink,or
•detectionbyanenginewatertemperaturesensorwhichprovidesan
analoginputsignaltotheTCM.Thissensorissuppliedandinstalledby
thevehiclebuilder.
4.3.1.1BASEDONRETARDERTEMPERATURE
Iftheretardertemperatureexceeds143ºC(290ºF),theTCMraisestheclosed
throttledownshiftpointsbyactivatingthepreselectdownshiftschedule.Use
ofthepreselectdownshiftscheduleforcesdownshiftstooccurathigherthan
normalroadspeeds,increasingcoolantowthroughthetransmissioncooler
andengineradiator.
Iftheretardertemperatureexceeds149ºC(300ºF),retardercapacitybegins
toreduce.Capacityreductioncontinuesuntilitisreducedtoapproximately
27%ofthemaximumavailableretardercapacity.
NOTE:Iftheoutputspeedincreases300rpmabovethespeedat
whichcapacityreductionstarts,fullretardationisrestored.
Iftheretardertemperatureexceeds166ºC(330ºF),theretardertemperature
indicatoroutputactivates.Thisilluminatesaretarderover-temperaturelight
thatalertstheoperatorofexcessiveretardertemperature.Theretarder
temperaturelightdeactivateswhentheretardertemperaturedropsbelow
159ºC(318ºF).Iftheretardertemperatureremainsabove166ºC(330ºF)for
tenconsecutiveseconds,anactiveDTCP273F(RetarderOilTemperature
SensorOverTemperatureCondition)isloggedbytheTCM.Whenthe
temperaturedropsandremainsbelow166ºC(330ºF)fortenconsecutive
seconds,theDTCbecomesinactiveandisstoredinmemory.
4.3.1.2BASEDONTRANSMISSIONSUMPTEMPERATURE
Independentoftheretardertemperature,ifthetransmissionsump
temperatureexceeds117ºC(240ºF),retardercapacitywillsimilarlybe
reducedasdescribedabove.Theover-temperatureindicatorisactivated
andtheover-tempDTCisloggedifthesumptemperatureexceeds121ºC
(250ºF)forfteenminutes,exceeds128ºC(262ºF)formorethanoneminute,
orinstantaneouslyreaches132ºC(270ºF).
4.3.1.3BASEDONENGINEWATERTEMPERATURE
Ifoptionalenginewatercapacityreductionand/orpreselectdownshiftsare
used,similarresponsesoccurbasedonexcessiveenginewatertemperature.
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