What fluid temp triggers the differential pump come on?

[Tomster]

I mentioned a few days ago that I drained and filled my differential. I've read that operating the pump with cold fluid may not be good for the differential pump, so I took her out for a spirited drive. I got my differential temp up to about 185F but never heard the pump come on. As soon as I got home, I used FORSCAN to toggle the pump on. FORSCAN was only able to run the pump at about 7 seconds at a time. So I did a few cycles until I heard the pump begin to pump fluid (sound changed).

So does anybody know at what point the PCM commands the differential pump to actuate?

I referenced the factory service manual and this is all it has to say about it.

"When the differential oil temperature reaches a predetermined level, the PCM grounds the differential oil pump relay
which activates the differential oil pump. Once the oil temperature is reduced to another predetermined level, the PCM
stops grounding the relay".

Does anybody know the answer from first hand experience or otherwise?

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[JohnVallo]

Tom,
Found this...

 

[Tomster]

Tom,
Found this...

Thanks John. I saw that too. That is the DTC temp. I know my diff pump is working because I hear that it is on leaving the track, but I never noted the temp which triggers it. I was out pushing the car to get it to come on today, but I guess street driving doesn't get it done. Thanks for checking.

 

[SVTinAR]

I'm surprised to hear the differential cooler pump is thermostat (or via computer temp input) controlled. Mine hardly builds any temperature on my 11 mile commute to work - maybe reaching 85 F or so. Same with the transmission. So I figured they circulated lubricant anytime the car was running which slowed it's warm up and retarded temperature unless really pushing it hard.

 

[Tomster]

I'm surprised to hear the differential cooler pump is thermostat (or via computer temp input) controlled. Mine hardly builds any temperature on my 11 mile commute to work - maybe reaching 85 F or so. Same with the transmission. So I figured they circulated lubricant anytime the car was running which slowed it's warm up and retarded temperature unless really pushing it hard.

I believe the transmission pump is circulating fluid anytime the clutch pedal is fully released. The differential works off a temperature sensor. Unless your temp reaches a very high number and doesn't work (293F), you wouldn't know until a DTC is thrown for overtemp. That was one of the reasons I asked the question so that I would know at what point the PCM triggers the pump to come on. I tried to get it going today and couldn't get it to trigger with street driving.

 

[galaxy]

What temps are you guys seeing on the diff? Freeway cruising, mine seems to hang around 120° over ambient on these cold days.

 

[Epiphany]

Same with the transmission. So I figured they circulated lubricant anytime the car was running which slowed it's warm up and retarded temperature unless really pushing it hard.

TR3160's use a gerotor pump (just not Tech Pack cars) that is driven off the front cluster in the transmission. So if the cluster is spinning the pump is indeed circulating fluid.

 

[SVTinAR]

Interesting - thanks for the info.

 

[Hi-PO Stang]

Wow ! This is interesting information. I thought the diff pump started running as soon as the engine fired up.

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