I'm interested in installing a temp gauge in our 6L90e transmission. Has anyone done this? I'm struggling with where to place the sending unit. This trans doesn't appear to have a "test port" so, it looks like either I weld a bung on the pan or splice it in the return line. Any thoughts or experience?Gary

Perhaps check with a nearby GM dealership for assistance - it's a GM transmission.

On my vehicles, when I service the trans and remove the pan, I have always drilled a hole and welded in a bung hole to fit the sender.Two things though: 1) make sure of position clearance so it doesn't touch anything in the trans, and 2) always put the sender in the pan, not in any return or send lines to the radiator. Only way to get accurate and true trans temp. Good luck,Egor

MDKMDK, Yeah I neglected to mention the GM dealer I worked with recently wasn't any help as the only "GM" solution is to enable the trans temp function in the information screen. Unfortunately, our particular configuration omitted this feature. I asked them to program it in but, they explained they could, or would, not do it as all they can do is reprogram existing functionality. They actually did this when they replaced the body control module and the instrument cluster... both of which we paid for! And even at that, they would not install the trans temp feature.The nearest GM dealer that will work on a RV is 105mi from us.Gary

While I am unfamiliar with this particular transmission I know on others I have had in the past that I wanted to put a gauge on if it didnt have a port in the pan for it like a maghytec etc pan, or test port on the trans I would splice into the hot line using either a compression type fitting with a 1/8 npt port on it or just cut a section of the hardline out and replace with rubber line and use double hose clamps with a 1/8 npt fitting. Never had an issue doing it that way.doing a very quick search similar to this but using the appropriate fittings whether barbed or compression or even if possible at the connection point of the hard line then there is no real "splice" in the line just have to find out what that connection spec is ie jic, npt, etc assuming there is enough space for the sender at that location which many times there is not. https://www.pegasusautoracing.com/productdetails.asp?RecID=906

FunTwoDrv wrote:MDKMDK, Yeah I neglected to mention the GM dealer I worked with recently wasn't any help as the only "GM" solution is to enable the trans temp function in the information screen. Unfortunately, our particular configuration omitted this feature. I asked them to program it in but, they explained they could, or would, not do it as all they can do is reprogram existing functionality. They actually did this when they replaced the body control module and the instrument cluster... both of which we paid for! And even at that, they would not install the trans temp feature.The nearest GM dealer that will work on a RV is 105mi from us.GaryDepending on the year of the vehicle/transmission, and if you have an OBD II diagnostic port available, you might be able to find and program a transmission temperature X-Gauge that will work with an after market scanner like the Scangauge II. However, if the trans/temp info isn't produced by the ECM or the engine's software/computer, then that won't work. Sorry, I can't be more help.

GM Trans Temp Gauge Install? | Good Sam Community

FunTwoDrv
Explorer
Dec 13, 2019
Kamphiker, it was an option with the 4500 chassis. However, I wasn’t successful in having GM reprogram the new instrument cluster to add it. So, now I’m leaning towards the Scan Gauge option as there is a nice place to install it on the dash.
Thanks for the advice everyone.

Gary
MDKMDK
Explorer
Dec 13, 2019
FunTwoDrv wrote:
Kamphiker, it was an option with the 4500 chassis. However, I wasn’t successful in having GM reprogram the new instrument cluster to add it. So, now I’m leaning towards the Scan Gauge option as there is a nice place to install it on the dash.
Thanks for the advice everyone.

Gary

I have mine sitting on top of the steering column in the Navion. It's line of sight with the other instrument cluster gauges. I run all 3 temp gauges - coolant, oil, and transmission (I think temps tell you a lot about what's going on under the hood) and either a DPF Regen monitor, or a charging voltage gauge as #4. Plenty of other options, too.
FunTwoDrv
Explorer
Dec 13, 2019
I like the idea of monitoring the oil and trans temps. I’d probably also use ambient temp and that’s about all. Water temp is already in the instrument cluster. And no way I’m looking at fuel mileage reading!
Ordered the Scan Gauge this morning...
Gary
MDKMDK
Explorer
Dec 13, 2019
FunTwoDrv wrote:
I like the idea of monitoring the oil and trans temps. I’d probably also use ambient temp and that’s about all. Water temp is already in the instrument cluster. And no way I’m looking at fuel mileage reading!
Ordered the Scan Gauge this morning...
Gary

Outside temp (ambient) is already in my cluster. There's all kinds of uesful optional gauges you can use, if you take the time to add them as X-Gauges. That's a pita, but if you're only doing one or two, it's no big deal.
I don't trust the SGII fuel economy numbers, and I've got a (maybe) more trustworthy mileage indicator as well, in the existing dash options. I like it because the MB diesel gets great mileage.
Chum_lee
Explorer
Dec 14, 2019
FunTwoDrv wrote:
I'm interested in installing a temp gauge in our 6L90e transmission. Has anyone done this?
I'm struggling with where to place the sending unit. This trans doesn't appear to have a "test port" so, it looks like either I weld a bung on the pan or splice it in the return line.
Any thoughts or experience?

Gary

You should put the temp sender where the fluid gets the hottest. Depending on your driving situation and the age of your transmission, that could be in the torque converter or lockup clutch, in one of many planetary gear sets, one of the many clutch packs, in the pan, or at the inlet to the cooler. (there may be other locations too) Get the picture? If you are headed for transmission issues, the fluid temperature varies all over the place depending on what the transmission is doing and how much power you send through it. There is no average temperature everywhere at every time. The point is, . . . . . don't overload the transmission and chances are, you'll be fine.

Chum lee
FunTwoDrv
Explorer
Dec 14, 2019
Chum lee,
Thanks, it appears my options are the pan itself or the cooler line. I found a supplier for the quick disconnect fittings and of course welding a bung on the pan is pretty straight forward. Right now I’m going with the Scan Gauge to see how that works.
Our C isn’t too heavy as we travel light and don’t have slides. But, we tow about 4500#’s and travel the rockies every summer. Just thought I should at least monitor the temp to ensure I’m not abusing the trans.

Gary
FunTwoDrv
Explorer
Feb 06, 2020
Update: Finally got around to installing the Scan Gage on our 2014 Chevy chassis C. It worked well but would not display trans temp. I contacted them for advice and was sent a data logger to capture info from the computers. Well, that helped and they were able to supply setup info that yielded the trans temp!
Since this was the key parameter that motivated me to purchase, I'm very happy with both the functionality and support.
Gary
ScottG
Nomad
Feb 06, 2020
That's very impressive support!

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