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do they run an actual temp sensor for it ? otherwise it will just be a calculation, if it is actual sensor could put in request to hptuners to add it if they know the address
 

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its prob not one of the regular used pids so prob wouldnt be added to the list, might be worth a msg to them see if it can be added to the list, if u have any scan tools that can see it u may be able to give them the pid address to make it easier if its possible
 
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I remember looking into this at one point but it is just a stupid thermostatic switch that turns on at a certain temp to throw an overtemp error (which is apparently waaay too high cuz heat cooks these diffs).

I seem to recall there being a PID for it but I think its at best just model based and not very accurate (using ambient temp and speed and maybe torque output if they got really fancy).
What you really want is a diff cooler and a real thermocouple or RTD to read the fluid temp.
I think weaponX makes one or people have DIY there are threads on here about it.
 
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I don't think there's a PID for it I think it just reaches a temperature and throws an alert on the DIC
This is my recollection. There's no "active control" of the diff temp, so there's no PID (which is only required for closed-loop control). It gets too hot, it tells you to stop doing donuts. You're the PID. If you don't want it getting too hot, assuming you know it's good on fluid, your only options are: slow down or install a diff cooler.
 

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This is my recollection. There's no "active control" of the diff temp, so there's no PID (which is only required for closed-loop control). It gets too hot, it tells you to stop doing donuts. You're the PID. If you don't want it getting too hot, assuming you know it's good on fluid, your only options are: slow down or install a diff cooler.
You are actually mistaken. PID in the context of an ECU stands for “parameter ID” or basically a variable in code. It doesn’t have to be a closed loop control variable like timing or afr like you would assume if it stood for the normal “proportional interval derivative” on a controls context.

So there absolutely could be a PID for diff temp and some PIDs are simulated/generated from a model based on other ECU inputs.

But either way the answer is “install diff cooler”


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Yeah. You're right. My bad. Sorry everyone. Too much FPV drone racing, where PIDs (closed loop control) are very important...

Those competative FPV racers are crazy.
 

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2011 CTSV Coupe M BLK LSX376-B15
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Discussion Starter · #13 ·
Agree, they are a very good. However, I have already invested in the AutoMeter Elite series gauges, so I am just going to purchase another one. ty
 

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I've actually been looking at this lately after rebuilding my differential. There has to be some sort of reporting of this on the CAN bus with all the other data, it's the only way the ECM can flash the stop doing burnouts message. Actually I think it's something like reduced power message. I'm about to tap into the harness and analyze the signal. It may very well just be a switch. There is nothing at all in HP tuners. I have a commercial CAN tool that will read every single message on the bus. I hooked that up to my Camaro last year and there were like over 390 PID's on 5 or 6 different buses. So basically I would hook that up, heat up the sensor, and see which signals are changing.

One thing I know is these things get freaking hot. I drove my car about 50 miles the other day in 80 degrees and put it up on the lift. After about one hour up there I took a IR temp reading on the diff case and it was 144F. Same as the oil pan. I do not know if this is normal operation but hope I didn't F something up in my rebuild causing extra heat.

Pretty sure my next "quick" project will be a cooler system for this.
 

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Discussion Starter · #15 ·
I've actually been looking at this lately after rebuilding my differential. There has to be some sort of reporting of this on the CAN bus with all the other data, it's the only way the ECM can flash the stop doing burnouts message. Actually I think it's something like reduced power message. I'm about to tap into the harness and analyze the signal. It may very well just be a switch. There is nothing at all in HP tuners. I have a commercial CAN tool that will read every single message on the bus. I hooked that up to my Camaro last year and there were like over 390 PID's on 5 or 6 different buses. So basically I would hook that up, heat up the sensor, and see which signals are changing.

One thing I know is these things get freaking hot. I drove my car about 50 miles the other day in 80 degrees and put it up on the lift. After about one hour up there I took a IR temp reading on the diff case and it was 144F. Same as the oil pan. I do not know if this is normal operation but hope I didn't F something up in my rebuild causing extra heat.

Pretty sure my next "quick" project will be a cooler system for this.
Very interesting update, looking forward to your finding. I will run a separate temp gauge when I install the cooling system, I agree, the rear is HOT as F in no time!
 

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One thing I know is these things get freaking hot.
The common rule of thumb for driveline parasitic power loss is 15%. If you assume that the gearbox is 10% and the Diff is 5%, and the engine is outputting, say, 100HP to cruise at HW speed, 5HP is being absorbed by the Diff. That's 3700 Watts. So that's roughly like 3x of your wife/girlfriend/s.o./personal-use hair dryer, blowing all their hot air inside the Diff for an hour. So yeah, there's plenty of heat.
 

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VERY interested in what you find. I installed a cooler with pump but have never completed the controls (for various reasons it fell off of my list) but I have a gauge/controller from Davies Craig that promises to do the job IF I could simply install their temp sensor or even a generic one. Of course the port on the diff is a little metric straight thread (I think 12mm) and I haven't yet sourced a proper sensor. I would LOVE to learn if the factory sensor could be utilized with or without utilizing the native CANbus connection. If i could tap into the CANbus somehow (meaning have HPT or some other device output an analog signal) that would be so sweet.
 

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I've actually been looking at this lately after rebuilding my differential. There has to be some sort of reporting of this on the CAN bus with all the other data, it's the only way the ECM can flash the stop doing burnouts message. Actually I think it's something like reduced power message. I'm about to tap into the harness and analyze the signal. It may very well just be a switch. There is nothing at all in HP tuners. I have a commercial CAN tool that will read every single message on the bus. I hooked that up to my Camaro last year and there were like over 390 PID's on 5 or 6 different buses. So basically I would hook that up, heat up the sensor, and see which signals are changing.

One thing I know is these things get freaking hot. I drove my car about 50 miles the other day in 80 degrees and put it up on the lift. After about one hour up there I took a IR temp reading on the diff case and it was 144F. Same as the oil pan. I do not know if this is normal operation but hope I didn't F something up in my rebuild causing extra heat.

Pretty sure my next "quick" project will be a cooler system for this.
Like I said above there is a temperature sensor but it is a simple digital input not an analog value where you can monitor the temp. It is a thermostatic switch that simply signals high when the specified over temperature is reached (which is way too high like everyone is saying).
So yes there is something on the canbus for the rear diff temp but its not what you are looking for. You either need an external temp monitoring system or find a spare analog input in the system and repurpose it to take in the signal for a real thermocouple or RTD sensor (like some people do for flex fuel sensors in cars where there wasn't an option from the factory).
 

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VERY interested in what you find. I installed a cooler with pump but have never completed the controls (for various reasons it fell off of my list) but I have a gauge/controller from Davies Craig that promises to do the job IF I could simply install their temp sensor or even a generic one. Of course the port on the diff is a little metric straight thread (I think 12mm) and I haven't yet sourced a proper sensor. I would LOVE to learn if the factory sensor could be utilized with or without utilizing the native CANbus connection. If i could tap into the CANbus somehow (meaning have HPT or some other device output an analog signal) that would be so sweet.
Use this adapter with any 1/8npt temp sending unit.
 

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