Help With Trans Temp Sensor

[Zebvance]

A while ago I got a trans cooler and a b&m trans temp gauge and I'm just now hooking it up. I ran all the wireing and the gauge lights up but does not read the temps. How can I trouble shoot to see If the sensor is working?

[MJCARENA]

Did you ground the sensor ? 

[Zebvance]

I grounded the gauge. There was no ground for the sensor. Just a signal wire coming from it.

[HOrnbrod]

I grounded the gauge. There was no ground for the sensor. Just a signal wire coming from it.

 

All temp sensors have to be grounded or they will not function. A single wire temp sensor (I suspect this is what you have) is grounded by the sensor body threads. Did you install it with a "T" fitting on the tranny coolant return line? Use Teflon tape or similar? Sometimes this can kill the ground. Verify the sensor ground by checking the resistance of the sensor body to a good ground point, like the engine block or the neg battery cable terminal. 

 

The tranny coolant lines have nylon quick connectors on each end - not a very reliable ground. The best location IMO for a tranny temp sensor is a bung hole in the tranny pan.

[Zebvance]

Oh ok I understand now. So what the easiest way to ground it? Here is a picture.

 

[HOrnbrod]

The temp sensor can't ground tied inline on a rubber coolant hose. You need to thread the sensor into an all metal location tied to ground.

[Zebvance]

Sorry I'm not getting this... Bare with me. So I have to mount the "T" to the frame or just run a additional wire from where the signal wire is mounted on the "T" to a ground on the body/frame?.

[ParadiseMJ]

I mounted the sender on the steel line.  The single wire sender grounds through the steel line...and then the tranny itself.  It's kind of problematic to add a ground, this was much easier.  I cut the steel lines from the tranny and flared the ends, put brass flare fittings on the ends with hose barbs.  I eliminated the metal line past this point.

 

 

It's all rubber hoses from here to the cooler and back.  I have the same set up on both Jeeps.  All the fittings I found at ACE hardware.  If you're cutting the steel lines, use a small tubing cutter and de-burr the ends to avoid the shavings going in to the trans system.  Note the date on this picture.  Have not had a single drip out of this since then.

[Eagle]

It isn't hard to add a ground. Take a length of wire, wrap it around the brass fitting, and clamp it solidly. (Or, better yet, solder it.) Connect the other end to any available bolt on the engine or frame -- just make sure you get a clean connection.

[Zebvance]

ok thanks guys. Ill try to add a ground tonight and see if that does the job. :cheers:

[HOrnbrod]

Not ideal, but quick:

 

Use a small adjustable hose clamp (like in ParadiseMJ's picture) around the body of the sensor. Either strip a bare wire and shove it under the clamp before tightening, or crimp a terminal lug under the clamp adjustment screw and attach the wire there, then tie the other end of the wire to a good ground point. The temp gauge should start indicating then.

[Zebvance]

Ok, now my question is will I be able to start it and let it idle and see the trans temps getting operation temps, or does not fluid run to the trans when its in park? Also what are normal temps that I should be seeing and what is to hot. There has been some bearing noise coming out of my trans since I bought the truck, but it shifts and runs fine.

[ParadiseMJ]

Not ideal, but quick:

 

Use a small adjustable hose clamp (like in ParadiseMJ's picture) around the body of the sensor. Either strip a bare wire and shove it under the clamp before tightening, or crimp a terminal lug under the clamp adjustment screw and attach the wire there, then tie the other end of the wire to a good ground point. The temp gauge should start indicating then.

 

That'd work too.  Whatever grounds it is good.

 

Ok, now my question is will I be able to start it and let it idle and see the trans temps getting operation temps, or does not fluid run to the trans when its in park? Also what are normal temps that I should be seeing and what is to hot. There has been some bearing noise coming out of my trans since I bought the truck, but it shifts and runs fine.

 

It will warm up a lot faster if you drive it...but it will circulate anyway via the pump.  It starts out at 100F so it should register close to that depending on YOUR climate/ambient temp.

[Zebvance]

So I hooked up the ground and drove it around and it was finicky. Light started coming on and of and the gauge needle started working once for about 5 seconds. I'm thinking the gauge is bad.

[coyote kid]

what brand is it?

[Zebvance]

B&M

[HOrnbrod]

So I hooked up the ground and drove it around and it was finicky. Light started coming on and of and the gauge needle started working once for about 5 seconds. I'm thinking the gauge is bad.

 

Do you have a multimeter? If so what's the ohms reading between the sensor brass shell and ground, then the reading between the sensor brass case on the wire you terminated on the output terminal going to the temp gauge? Sounds like the wire you installed from ground to the sensor shell is err, finicky.

[Zebvance]

Here is a picture of the ground.

 

 

 

I did meter the wires hooked up to the gauge and I'm wanting to say I was getting like 8 ohms from the signal wire.

[coyote kid]

I had a b&m at one point I had lots of issues with the needle sticking and having very jerky movments

[Zebvance]

Yea I'm thinking I'm going to just go get a new gauge. Then go from there.

[MJCARENA]

You might want to move the ground to the sensor itself and not on the T fitting if you used teflon tape to seal it.