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Discussion Starter #1 (Edited)
Hey all,

I've searched and read through a bunch of the posts on getting the tranny fluid temp via ODBII and find myself a bit confused. I see some posts saying the Scan Gauge II works, but they read other posts that say the temperature is not accurate. Is there a definitive answer on this? I also see numerous OLD Scan Gauge II's for sale (used), but I suspect they likely have older firmware. Best to avoid these and buy new?

Edit...2019 4.0

Grant
 

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I don't see what year vehicle you have. My Scanguage II has no trans temp display. And, I cannot get transmission temp with ThinkCar, even though it has transmission diagnostics. My understanding is that the 2005 Frontier did not have trans temp avail thru OBD II. Thought I read that it had been added in later years, but not sure. Subscribing for updates.
 

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I have a 2005 Frontier with a automatic transmission and I have a scangauge II. I have entered the codes for the transmission temp and still don't get any readings. The codes I have entered are for later years Frontiers so I figure that is why they won't read the temp.
 

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It's probably in there, the issue is getting it. The service manual requires using the Nissan scan tool to access the transmission fluid temp for some service items. In particular the fluid check/fill procedure. My OBD Link LX does not read it but OBD Link does list Nissan and Transmission temp for their MX+. I'm going to try that one before I go with a after market sensor and gauge.
 

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I hope you are able to get this to work, but if it doesn't or you decide that you'd rather have a dedicated temp gauge, several folk including myself have added one by using the Nissan Jatco pressure testing port on the right side of the transmission next to the cooler lines. My build thread, Silver Surfer, has the part#s required to use AutoMeter parts.

318202
 
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So I bought the Scan Gauge II and programmed the codes from their website for Nissan Frontier transmission temps and it worked perfectly. I just towed about 2,000 lbs just over 100 miles out and about 4,000 lbs backon an 80 degree day. This was in a 2017 4 cylinder, 2wd auto. And yes I know I was over the towing spec on the way back. Having the the transmission temps was comforting. Even with a 4,000 lbs tow the transmission temps stayed well under 200. I was usually cruising at 60 mph, on level ground the temps stayed in the 160 to 170 range. On long uphills on the interstate AT2 (pan temp) would rise to 190 but AT1 (return from the cooler) would usually stay well below 180, usually in the 160s. The picture above was cruising on level ground at 60 mph.
 

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Discussion Starter #7
I was told that the "fluctuating" temp...the one that changes often with load etc, was the torque converter temp sensor, and that the "stable" one was the pan temp.

Does anyone know for sure what/where these sensors are? Are they even the same on the 4 vs cyl?

I have one that fluctuates a LOT when towing....on flat/even tows stays the same as the other (around 160), but will spike over 215 for 10-20 seconds during harder pulls....
 

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I was told that the "fluctuating" temp...the one that changes often with load etc, was the torque converter temp sensor, and that the "stable" one was the pan temp.

Does anyone know for sure what/where these sensors are? Are they even the same on the 4 vs cyl?

I have one that fluctuates a LOT when towing....on flat/even tows stays the same as the other (around 160), but will spike over 215 for 10-20 seconds during harder pulls....
The one that fluctuates and runs higher than the other is the converter! Which would be AT2 if programmed correctly.
 

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Discussion Starter #9
Thanks for the comment. I was just off reading some other forums and have confirmed that yes, it seems that torque converter temps do fluctuate under load a lot, and often see very high temperatures as well....even over 350 degrees for short bursts.

I was worried when I was seeing 220 for short times (15 seconds for example) before slowly dropping back to the 160s...
 

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Discussion Starter #10
Just ran across this on another site and seemed appropriate:


Here is a quote from the Orange ($8.95) GM manual:
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"OIL TEMPERATURE MEASURED AT CONVERTER OUTLET TO COOLER.

300F is the maximum temperature. (Workhorse says 350F). This is the normal place to install a temperature gauge or signal. The temperature in this location will vary significantly with each vehicle start-up or hill. If the temperature reaches 300F (350F), reduce throttle. To lower the transmission temperature with the transmission in NEUTRAL, run the engine at 1,200 RPM for 2-3 minutes to cool the oil. Do not allow the converter outlet temperature to exceed 300F (350F).
Keep a close check to prevent the engine cooling system from overheating.

300F would be typical of rocking the vehicle in mud, snow, or sand, or a transmission in stall (full throttle, no vehicle movement). When the transmission is in stall, the transmission will develop heat at a rate of one degree per second of stall.

OIL TEMPERATURES MEASURED IN THE SUMP

150F -- Minimum operating temperature for continuous operation. It is possible in low ambient temperature to overcool the transmission with oil to air-type coolers; it is hard to overcool if used in conjunction with oil to water coolers installed in most standard automotive radiators.

190F-200F -- Maximum oil level checking temperature. Beyond this, readings are not reliable because of expansion.

285F -- Maximum sump/oil pan temperatures for short duration such as a long hill climb.

300F -- Metal parts inside the transmission begin to warp and distort in varying degrees, seals melt rapidly, and transmission fluid life is extremely short due to oxidation and distress.

AUTOMATIC TRANSMISSION FLUID OXIDATION Automatic transmission fluid
can provide up to 100,000 miles of service before oxidation occurs under normal operating temperatures of about 170F. Above normal operating temperatures, the oxidation rate doubles (useful life of the fluid is cut in half) with each 20 degree increase in temperature. The approximate life expectancy at various temperatures is a follows:
Degrees F Miles
175 100,000
195 50,000
212 25,000
235 12,000
255 6,000
275 3,000
295 1,500
315 750
335 325
375 80
390 40
415 Less than 30 minutes
 

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A couple of comments on different items in this thread:

1 The 4 and 6 cylinder share the SAME AUTOMATIC TRANSMISSION, model RE5R05A. They are just programmed differently with different shift points and lockups (the 4 cyl only locks up in 5th gear the 6 cyl locks up in 4th and 5th). In addition the 6 cyl has one extra plate in the lockup clutch. There may be other differences but these are the ones that stuck out to me reading the shop manual.

2 There seems to be only one transmission fluid temp sensor outside of the control valve/transmission control module (one part). The schematic shows only one ATF fluid temp input into the TCM. Also the description of the components of the TCM lists a temperature sensor. So it seems that one fluid temp sensor is inside the TCM and one is external. There is no diagnostic procedure or discussion in the service manual for an external temp sensor. There is a trouble code and diagnostic discussion for AT temp sensor 1. So it seems the system only uses and creates trouble codes for ATF fluid temp sensor 1, the one located inside of the control valve/TCM. By the way the repair for a faulty AT temp senor 1 is to remove and replace the control valve/TCM assembly. As a side note I cannot find any reference or listing for a AT temp sensor in any of the the parts catalogs.

3 So based on the the above observations and other users comments I will make the following assumptions. AT fluid temp 1 is pan temp since it is inside of the control valve/TCM which is located in the pan and usually bathed in ATF fluid during operation. Also based on my observations AT fluid temp 2 is probably the temp of the fluid exiting from the torque converter since you can make it run up fast by pressing the accelerator while in drive and holding the brake and it recovers quickly when you put the truck back to park or neutral. AT2 is also the temp that runs up high during long uphills while towing and recovers fast coasting down the other side while AT1 rises very little and slowly by comparison under stress.

4 The 4 cylinder can tow a ton of crap. This is obviously helped by having the same transmission as the 6 cylinder with its 6,500 lb tow limit. I have just towed at least 4,000 lbs on I95 from Providence to New London and then from Orient to home on secondaries. Eastern CT is quite hilly and while she down shifted, sometimes all the way to third, she had little trouble climbing 2 mile long hills at 60 mph with the transmission temps staying well within tolerable limits. If I had to tow large loads on a regular basis I would have a larger truck but I have no doubt that that the 4 cylinder Frontier is up to the job when needed.

5 The Scan Gauge II works well for transmission temps with the supplementary codes entered. I have no doubt that its readings are accurate based on the temps it reads at startup and how the temps rise and behave underway. Also AT1 behaves and goes to temps that are very similar to how my Chevy Silverado behaved which had a transmission temp readout in the driver information center.
 

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It's probably in there, the issue is getting it. The service manual requires using the Nissan scan tool to access the transmission fluid temp for some service items. In particular the fluid check/fill procedure. My OBD Link LX does not read it but OBD Link does list Nissan and Transmission temp for their MX+. I'm going to try that one before I go with a after market sensor and gauge.
i thought my obd2 link lx does but nope but great for my towing watcching cooling temps .. wonder about mx version maybe.. let us know if mx did if not i found other post about putting one in with gauge..
 

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i thought my obd2 link lx does but nope but great for my towing watcching cooling temps .. wonder about mx version maybe.. let us know if mx did if not i found other post about putting one in with gauge..
I have the OBDLink LX so I tried the MX+ since it promised support for a 2017 Nissan Frontier and that it supported transmission temp. Alas it didn't. Scan Tool eventually refunded my money and did say that there was an issue with the software and Nissan Frontiers. They said they had a support ticket with another Frontier owner for the same issue and we're working with the software developer to figure out what is wrong. I can wholeheartedly recommend the Scan Gauge II.

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ah thanks. for info ok i still keep lx while i fix family and friends car (under table repairs).. will go get that one, Program like in post somewhere to program it then use it.
 
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