Scan Gauge II

[Atlee Hokie]

Can the Scan Gauge II read the transmission temperature of the 4sp transmission on the 2003 Chevy chassis?

[booster]

Originally Posted by Atlee Hokie

Can the Scan Gauge II read the transmission temperature of the 4sp transmission on the 2003 Chevy chassis?

Yes, it can. We use ours for that all the time.


You do have to manual enter the codes for the Chevy transmission readout when you set it up, so beware of that. It is, IIRC, 3 separate long number strings so care is needed as it very easy to do a typo. It took me several tries.


Also be aware that the Scangauge is reading the temp at the same place the computer is inside the transmission. It does not necessarily match what you would see with a pan temp gauge. I put in a pan gauge for comparison for a while to test that. The Scangauge temp will climb much faster than the pan temp would at application of a big load like seen in climbing steep hills, in particular. Steady state on the level it reads the same as a pan temp.


The 2004 would have come from the factory with Dexron IV fluid in it, but it is a good idea to get it swapped out to the currently used Dexron VI synthetic as it is much better at high temperatures. By sure to use real Dexron VI that says that it has passed the GM standard on the bottle. There are lots of others that say they are "Dexron VI) compatible and they would not have passed the GM testing standard, or were not submitted for testing. Valvoline makes a Dexron VI that is to standard and works well, while be less expensive than the GM branded fluid.

[jojobafanzi]

Transmission optimum temperature is 175 degrees F. Most of the heat that reduces transmission life span is created in the torque converter when the fluid changes direction. If the torque converter is not in lockup, it is slipping and creating maximum heat. Most transmission cooling lines are around 5/16". The torque converter is the transmission fluid pump. Additional transmission coolers can help but a separate transmission cooling system pumping from and back to the sump is the most effective way to prevent overheating of the transmission in extreme conditions. If you have a transmission temperature gauge installed in your vehicle, you can observe the ease of overheating a transmission. From a full stop, just do three jackrabbit starts. That means put the pedal down and go through all your gears as fast as you can and then come to a full stop. Do this three times and you will observe your transmission temperature will spike past 250 degrees F. Then drive normal and observe the transmission temperature. It will take a long time for the factory transmission cooling system to reduce the heat to a desirable temperature. The cooling lines are small and the cooling system is just not designed for extreme conditions such as the test I just mentioned. Automatic transmissions just make lots of heat which is your enemy. If you really want to protect your transmission from heat, a auxiliary cooling system is your best route. You need to move more fluid through larger hoses and cooler than stock.

[booster]

Originally Posted by jojobafanzi

Transmission optimum temperature is 175 degrees F. Most of the heat that reduces transmission life span is created in the torque converter when the fluid changes direction. If the torque converter is not in lockup, it is slipping and creating maximum heat. Most transmission cooling lines are around 5/16". The torque converter is the transmission fluid pump. Additional transmission coolers can help but a separate transmission cooling system pumping from and back to the sump is the most effective way to prevent overheating of the transmission in extreme conditions. If you have a transmission temperature gauge installed in your vehicle, you can observe the ease of overheating a transmission. From a full stop, just do three jackrabbit starts. That means put the pedal down and go through all your gears as fast as you can and then come to a full stop. Do this three times and you will observe your transmission temperature will spike past 250 degrees F. Then drive normal and observe the transmission temperature. It will take a long time for the factory transmission cooling system to reduce the heat to a desirable temperature. The cooling lines are small and the cooling system is just not designed for extreme conditions such as the test I just mentioned. Automatic transmissions just make lots of heat which is your enemy. If you really want to protect your transmission from heat, a auxiliary cooling system is your best route. You need to move more fluid through larger hoses and cooler than stock.

Now days, the 175*F is going away quickly with synthetic fluids and fuel efficiencies focus. The GM 6 speeds used in lot of pickup and the vans after 2010 routinely run at 210* by numerous accounts and seemed to control the temp to hold it there, so very different. They 6 speed and higher transmissions also can lock up the converter nearly all the time because of the more gear selections. The change in 2010 to the 6 speeds in the van pretty much completely cured the transmission overheating issues with no other changes to the coolers or radiators.



The problem with Chevies is the lockup as has been mentioned many times over the years. Big radiators, add on fans, big oil coolers are often not enough to handle it well. I went through all of that in 2010 and didn't get rid of the overheating on long climbs until I reprogrammed the transmission shift and lockup points with a tuner. It is being discussed now in another thread even with links to the reprogramming threads.

[mkguitar]

I looked at Scan Gauge and in the end went with the OBDFusion app on my iPhone and a OBDII dongle. the costing was about 1/2 and I have much more available- I've dedicated an old iphone to this task and use it in my various vehicles incl 2005 Chev 3500 chassis



I usually monitor:


Engine Temp
RPM
MAF
Fuel rate
Battery volts
O2 sensors 1 & 2
Trans fluid temp
Engine oil temp
Engine oil pressure


I can also read/reset codes

[booster]

Nobody has mentioned Bullydog yet, but it might be worth a look especially if you want to be able to be tune also. The full time display is also the communicator for the programming plus it allows you to store multiple tunes in the display for easy program swaps without having to use a the laptop.


I have not looked the them in a while, so I am assuming they are still available and for the Chevy gassers. Cost is not inexpensive but probably a bit less than a Scangauge and an HPtuner. When I looked a while ago the programming looked very close to the same as for the HPtuner.