HDJ Bad Tranny Temp Sender? (1 Viewer)

[jellis]

I just installed a tranny temp sender at the outlet of the hot side hard line near the radiator on my HDJ81 (3" exhaust has made the outlet port on the tranny very difficult to access). As far as I can tell the gauge appears to be working correctly (i.e., reading roughly ambient temps after sitting all night, reading near engine temps while running). While towing my M101 military camp trailer up a hill back to my house after a camping trip this weekend, my ATF idiot warning light came on a few times while my gauge was only reading around 220F (~104C).
Now, I'm assuming that my idiot/warning light temp sensor is broken and triggering at a lower-than-spec temperature (~304F/150C I think is the spec). The alternative is that the fluid is somehow losing nearly 80F in a few feet of hardline which isn't really possible.

Is there anyone running an aftermarket gauge installed in this location that has pushed their trans over 110C and not had their idiot light come on? Just want to make sure I'm not missing something, that's not a good warning light to ignore!
For the benefit of future readers, I've been having the ATF warning light trigger "too easy to me" over the last year so this would definitely explain why.

Also worth noting, I installed a pressure sensor on the return line (coming out of the radiator exchanger) for S&Gs and it routinely reads 0 PSI under load, 4-6psi at idle. This makes no sense to me. I doubt anyone else has done this but any insight/experience would be interesting!

 

[Squash]

I would trust the gauge.
One thing to keep in mind when going up hills is to grab some speed on the down hill or flats and once you start loosing speed lock the tranny out of O/D.
If you allow the tranny to shift often your clutches heat up and this heat will trigger the idiot light.
On another note this same thing happens when driving in mud/deep snow, you may be trying to maintain speed with the skinny pedal while the tranny is shifting up and down creating heat. Do yourself a favour and drop the O/D or in serious crap 2nd or shift out of H and into L.

Otherwise beef up the cooling.
Once owned a ride just like your sig!

 

[Echelon]

Jellis. Do you have the old sender still? If you do could you measure the threads? I'm wanting to replace my sender with a aftermarket one and I need to know the thread size to make an adapter. I'm currently 10k miles from my 80.

 

[jellis]

@Echelon, I'm not sure because I never removed my factory sender. It's a total PITA to get to because I have a 3" exhaust running right next to my driveshaft/transfer. So I put the temp sender for my multigauge up near the radiator where the hard lines end instead, that was MUCH easier for me. There should only be a few degrees difference between the two locations.

Looks like it's a BSP thread, not sure what size though. A lot of folks have a machine shop add an additional port to the fitting for an aftermarket sender in order to keep their original sender/light functionality:
hdj81 a442f transmission temp guage and test port location

Wholesale Automatics sends a new fitting drilled for the additional aftermarket sender with their temp gauge kits, if you called them up I'm sure they know the thread specs off the top of their head.

 

[Echelon]

The sender I have is too big to drill and tap the end of the union. That's why I'm wanting to just put it where the oem one goes. I'm pretty sure it's m16 or m18. Somebody tried m14 and it was too small.