Originally Posted by 4mydogs

I finally got my mechanic to install the AutoMeter transmission temp gauge for me. He put the sending unit on the line just as it comes out of the pan, going toward the radiator/trans cooler. It is an electrical gauge that reads from 100 to 250 degrees. I haven’t had a chance to go for any really long road trip, but I did drive about 15 miles on pavement at varying speeds up to 55 mph with lots of starts and stops. I also got on a dirt road and went about 5 miles in 4WD High and Low. Back into 2WD did some wheel spinning quick accelerations, in dirt of course . The gauge never went above 100 degrees, in fact it never appeared to move except when I shut off and restarted the engine (the gauge needle rests just below the 100 degree mark). I need to do some more driving, but I wondered: is it possible that the reading is correct at 100 degrees, or is it not working properly? I can’t imagine that the temp would stay so low in start and stop traffic. I thought it would at least get up to around 130 on average.

Anybody out there with a transmission temp gauge want to tell me what their usual operating temps are?

Originally Posted by 4mydogs

As I understand it, the line from the trans to the cooler leaves the pan on the pass side and the return line is on the opposite side. The sensor is in direct contact with the fluid in this first line via a "manifold" which was cut into the line. Basically is has 3 openings in a tee shape: one at each end for the fluid to flow through, and a third for the sensor to contact the trans fluid.

Originally Posted by TechWrench

I haven't actually looked at the auto that comes in the 95 SR5, but i thought it was basically the same type as the auto in my '03, a 340H or F series 4 speed. If so, it seems very unusual, but not impossible, that they (Toyota) would have routed the cooling lines out the side of the sump pan. This configuration would make it very difficult to remove the pan for service. And the plumbing that would have to be done to connect the lines inside the pan on the output side to the pressure source wouldn't seem to make good mechancial sense. In any event, I understand the 'T' fitting you describe. But my next question would be how it was installed. If the branch of the 'T' that the sensor goes into was installed in the up position, it is possible that it could be come air bound, and the sensor may not be in contact with the oil at all. This could explain the poor operation.

Originally Posted by Transdude

Did you ground the sender or the sender block itself, or just the gauge?

-John

Originally Posted by 4mydogs

I thought of that, because I see that my mechanic installed the manifold with the sensor branch in an upward position, between horizontal and 45 degrees upward. I am going to loosen the fittings and correct that -- I think it should be straight down. But, I did put the sensor down into boiling water, with no result.

Originally Posted by Transdude

The fluid is under a lot of pressure- an air bubble cannot form, however even if it could, heat would be transferred form the rest of the assembly to the sender.

Again, with an Autometer gauge, the sender needs a ground.

Try hose clamping a wire to the sender and putting it to ground, it should fix the problem.

-John

Originally Posted by 4mydogs

That makes sense, and I realize where I went wrong. Had I been able to use the compression fittings supplied by AutoMeter, the sender would have been grounded through the steel trans fluid line. But because I had to use hose, there is no ground. I'll try running a ground to the sender and see what happens. Thanks for your help. Maybe I should shop for a new mechanic.
Do you think I am OK with hoses and double clamped connections? I've been running it that way for almost a week with no leaks or apparent problems.

Originally Posted by 4mydogs

John (Transdude): The lack of a ground for the sensor was the problem. I now have a trans temp gauge. Thanks for your help.

Techwrench: I am going to put steel lines on my New Year's list of things to do for my truck. Thanks for your help, too.

Yotatech is the best!

Originally Posted by Transdude

Rubber lines are fine as long as the end of the steel line that it is connected to has a double flare at the end (this, in conjunction with a hose clamp, will keep the line on just fine).

There are literally hundreds of factory applications that utilize at least some rubber line.

-John

Originally Posted by SLC97SR5

What is a good operating range for Auto's? I've searched and can't find a straight answer. Thanks all.

Originally Posted by 4mydogs

I don't know that you'll find a definitive answer. But the general consensus seems to be that "normal" operating temp is 150 - 180, and that it isn't unusual to see "spikes" of up to 250 when pulling steep grades or when the TC isn't engaged for long periods. But the temp should quickly fall back into a normal range once things level out. This is what I have observed with my 4Runner.

Another question that I had but that NOBODY could answer was what temp activates the auto trans temp light.

Originally Posted by Robinhood150

Since installing my gauge the temp has gone to 250 (as measured where the rubber hose meets the hardline on the supply side) and the light still hasn't come on.