Frontal Area

[Brian B-P]

Originally Posted by bdornbush

I guess my 2014 Jeep Grand Cherokee has a built-in trans temp gauge...
Does anyone have knowledge about how to look at trans temps while towing?

On one extreme, you can plumb in a sensor and wire it to a gauge. On the other extreme, the Dodge/Chysler/Jeep specific XGauge code list suggests that a ScanGauge plugged into the OBD port may be able to show transmission temperature - easy, if the code works for your vehicle.

[azjack]

In my Jeep I take a quick look at the engine info once in a while when working the vehicle and expect and find each item near the midpoint of the gauge.
When I had a couple of smaller motorhomes with the Ford V-10 the stock gauges gave very little info so I used the scan gauge, a good tool.
Jack

[ATHiker]

Originally Posted by Nindy

Interesting. So much to think about. I will be towing my 17B with a 2014 Jeep Grand Cherokee Diesel in mid-March. Will make a not-so-direct fun trip from Chilliwack to Missouri, taking whatever route suits the weather at the time. I will give a report on how we do! The Jeep should be a beast pulling the trailer. I already get 30 mpg on the highway and 26-27 combined.

Could you please share the max tongue weight and the specific payload (value shown on the inside of the driver door) for your Jeep Grand Cherokee Diesel? The Jeep GC diesel looks very interesting to me if my Toyota Tacoma is not up to pulling the Escape 21.

[ATHiker]

Originally Posted by padlin

My temp seems to run about 100 over ambient once it warms up. Found this chart a few years back.

I recently installed an Ultraguage in my Toyota Tacoma to specifically monitor the transmission temp. I found out that the transmission warning light on the Tacoma does not illuminate until 300 deg. F.

[padlin]

On my 06 GMC truck I had a questionable tranny, slip on hills and such. While towing up and down hills the Scangauge would show 100 degree swings while the needle indicator on the dash wouldn't even budge.

[Mike Lewis]

Originally Posted by ATHiker

I recently installed an Ultraguage in my Toyota Tacoma to specifically monitor the transmission temp. I found out that the transmission warning light on the Tacoma does not illuminate until 300 deg. F.

I recently asked my local Toyota dealer about exchanging the transmission fluid in my 2013 Tacoma for synthetic transmission fluid. I was told that it already had synthetic fluid; it came from the factory that way. That would explain the 300 deg F. trip for the warning light. I haven't researched this any, though.

[Rossue]

Am suddenly reminded of the term "idiot lights". Hope you never see that light for trans come on because it may be too late.
Automatic Transmission Temperature Chart - See how fast high heat can ruin your transmission.

The effect is also cumulative.**Short term exposure to high heat levels (or even prolonged**exposure to moderate heat)***can break down the oil to the point where even very short episodes of overheating will lead to failure.

[santacruzer]

Great chart, going to print a copy and keep it in the glove box! I use a ScanGauge on my Tacoma, and have never gone above 225, and then only briefly. The Tundra has a built in tranny temp gauge, and it's needle has never moved above Normal, but I still plan on using a Scan Gauge there as well, eventually.

[Brian B-P]

Originally Posted by azjack

In my Jeep I take a quick look at the engine info once in a while when working the vehicle and expect and find each item near the midpoint of the gauge.

That's typically how gauge calibration is done, although not always. I've heard of instrument panels with the gauges oriented so normal is horizontal for all needles - or vertical for all needles - except road and engine speed, both of which have no "normal". Unfortunately, in most vehicles styling and marketing seem to have been more important to the instrument design process than function.

A good example of non-functional instrument design, and a pet peeve of mine, is speedometers which go up to double the speed the vehicle will ever be driven, so the marking are jammed in twice as tight as they need to be and can't be read accurately or quickly.

Originally Posted by azjack

When I had a couple of smaller motorhomes with the Ford V-10 the stock gauges gave very little info so I used the scan gauge, a good tool.

The scan tools typically display digital values, which are precise but difficult to read at a glance. The gauges in my motorhome can't be read very precisely, but they show meaningful information at a glance. The gauges have probably changed over the years, but mine has coolant temperature, oil pressure, and transmission temperature (plus engine speed and of course road speed and fuel level) - pretty close to what I would ideally want to see to ensure that the drivetrain isn't overloaded, but oil temperature would be a good addition.

[Ron in BC]

Originally Posted by ATHiker

I recently installed an Ultraguage in my Toyota Tacoma to specifically monitor the transmission temp. I found out that the transmission warning light on the Tacoma does not illuminate until 300 deg. F.

I thought everyone had a Scan Gauge and I was the only one with an Ultragauge

Mine's a couple of years old and I don't think it reads transmission temperature on my Ford Ranger. Did you have to put in any specific codes to make it useable on your Tacoma?

Ron

[Brian B-P]

Originally Posted by ATHiker

Could you please share the max tongue weight and the specific payload (value shown on the inside of the driver door) for your Jeep Grand Cherokee Diesel?

I've never seen a tongue weight limit (or any trailer-specific limit) on a door placard, but of course I haven't come close to looking at every vehicle.

The 2015 Grand Cherokee owner's manual from the Jeep Owners Site may be useful. About the placard, it says:

Certification Label
As required by National Highway Traffic Safety Administration regulations, your vehicle has a certification label affixed to the driver’s side door or pillar. This label contains the month and year of manufacture, Gross Vehicle Weight Rating (GVWR), Gross Axle Weight Rating (GAWR) front and rear, and Vehicle Identification Number (VIN). A Month-Day-Hour (MDH) number is included on this label and indicates the Month, Day and Hour of manufacture. The bar code that appears on the bottom of the label is your VIN.

This doesn't even have payload, which I find surprising, so perhaps there's more on the label than listed in the manual.

This is all the manual says about tongue weight:

Tongue Weight (TW)
The tongue weight is the downward force exerted on the hitch ball by the trailer. The recommended tongue weight is 10% to 15% for a conventional hitch. You must consider this as part of the load on your vehicle.

WARNING!
If the gross trailer weight is 3,500 lbs (1 587 kg) or more, it is mandatory to use a weight-distributing hitch to ensure stable handling of your vehicle. If you use a standard weight-carrying hitch, you could lose control of your vehicle and cause a collision.

... in other words, over 525 pounds of hitch weight, they require WD. This won't vary due to the different curb weight of different versions of the vehicle (such as diesel versus the other engines).

[Brian B-P]

Originally Posted by padlin

On my 06 GMC truck I had a questionable tranny, slip on hills and such. While towing up and down hills the Scangauge would show 100 degree swings while the needle indicator on the dash wouldn't even budge.

The Scangauge and dash instrument were supposed to be showing the same value - presumably the transmission temperature - from the same sensor location?

[Brian B-P]

Originally Posted by Mike Lewis

I recently asked my local Toyota dealer about exchanging the transmission fluid in my 2013 Tacoma for synthetic transmission fluid. I was told that it already had synthetic fluid; it came from the factory that way. That would explain the 300 deg F. trip for the warning light. I haven't researched this any, though.

I'm not surprised. Manufacturers are going to synthetic fluids (for engine oil and for both manual and automatic transmission fluids) to meet their performance targets. My 2004 Focus had synthetic (manual) transmission gear oil, my 2012 Mazda has synthetic engine oil (as is all 0W-20 oil), and I assume my 2004 Sienna has synthetic ATF.

[Brian B-P]

Originally Posted by Ron in BC

I thought everyone had a Scan Gauge and I was the only one with an Ultragauge

I have an Autel MaxiTrip, yet another option (chosen simply because it was inexpensive).

Originally Posted by Ron in BC

Mine's a couple of years old and I don't think it reads transmission temperature on my Ford Ranger. Did you have to put in any specific codes to make it useable on your Tacoma?

That's a continuing challenge. Even with the popular Scan Gauge, codes required for many vehicles are unknown. If you're lucky, eventually someone finds what you need and shares it in a forum or through the gauge manufacturer.

[santacruzer]

I had to look for some time to find the Tacoma code, then I had to send the ScanGauge unit in for an upgrade, since previous iterations didn't support tranny temps for that year Tacoma. You have to dig a little.

[Dave Walter]

Originally Posted by padlin
On my 06 GMC truck I had a questionable tranny, slip on hills and such. While towing up and down hills the Scangauge would show 100 degree swings while the needle indicator on the dash wouldn't even budge.

Originally Posted by Brian B-P

The Scangauge and dash instrument were supposed to be showing the same value - presumably the transmission temperature - from the same sensor location?

My toyota has at least two sensors on the transmission, and they often show significantly different temperatures on my scan gage, one being much more stable than the other. Maybe padlin is seeing results from different sensors.

[santacruzer]

Originally Posted by ice-breaker

My toyota has at least two sensors on the transmission, and they often show significantly different temperatures on my scan gage, one being much more stable than the other. Maybe padlin is seeing results from different sensors.

I'm not understanding this. Do you flip back and forth between two different readings on your ScanGauge?

[Rossue]

Originally Posted by ice-breaker

My toyota has at least two sensors on the transmission, and they often show significantly different temperatures on my scan gage, one being much more stable than the other. Maybe padlin is seeing results from different sensors.

One must be the Canadian sensor(sp?)

[padlin]

Originally Posted by ice-breaker

My toyota has at least two sensors on the transmission, and they often show significantly different temperatures on my scan gage, one being much more stable than the other. Maybe padlin is seeing results from different sensors.

Don't know if that was the case, it's certainly possible.

[Dave Walter]

Originally Posted by santacruzer

I'm not understanding this. Do you flip back and forth between two different readings on your ScanGauge?

I sometimes display both sensors at same time on my scan gage, call them TF1 and TF2.