Robert Rausch

My truck is a '95 2-WD 2500 with 326,000 miles on the odo. The trans is an ATS Stage IV with 219,000 on it.
It had worked flawlessly until last June. during the first part of a 1,600 mile trip, if I got above 60 mph weird things happened. Trans would drop out of O.D. or the TC would lock and unlock relentlessly, or both. My solution was I just kept it under 60--I didn't want to take a chance on pulling into an unknown trans shop out in the boonies. So I drove under 60 for 1,000 miles until I pulled into my home. Next day the trans worked great--as quickly as the problem had surfaced, it disappeared. I took it to a good diesel shop, but they couldn't diagnose any problem.

All was fine again until about 6 weeks ago when the T.C. began to lock and unlock at odd times. When this would occur it would lock and unlock every 4-5 seconds and it drove me nuts. However, this time it only happened from initial lockup to about 60, and above 60 it went away.

Then things got really weird. It started losing O.D. cyclically--I'd be driving along about 65 and O.D. would suddenly drop out. Then O.D. would kick back in, then drop out, then kick back in. O.D. was starting to act like my T.C. locking and unlocking. Then I lost O.D. all together one night. I pulled off the freeway, stopped and checked my trans fluid, started back on the freeway and O.D. stayed engaged while I drove home (10 miles).

Now I had also had a trans cooling line leak for awhile. So I would monitor the fluid level--I kept a gallon of Dexron in the back--I'd check it and if needed, top it off every 2-3 days. So last Monday I got a day off, and I pulled the old trans lines off and replaced them with rubber trans lines. I wired a 1,000 ohm resister into the wiring harness for the trans line temp sensor. And allllllllll my trans problems went away. I've put 250 miles on the truck since I replaced the trans line temp sensor with the 1,000 ohm resistor and the trans has never once lost O.D., nor has it unlocked and locked... not once! So it looks like I accidentally fixed my problem with the resistor. Hope so.

Robert Rausch

I've put about 350 miles on my truck since I swapped out the stock trans line temp sensor for a 1,000 ohm resistor and the truck has not unlocked/lockup once while driving along! I think the resistor's steady 1,000 ohm signal somehow has a calming affect on the trans in contrast to the stock sensor's signals.

Lary Ellis (Top)

That's GREAT news Robert!

joem

I may need to try that, Mine has kicked out of OD at 75-80mph on flat ground twice now, pegged the tach way past 3K with a huge puff of blue smoke both times and even lit up the OD/OFF button all on its own. I thought about getting heavy duty valve springs so it doesn't blow up like this one did, mine sounded pretty darn close to this too

Robert Rausch

Thanks Lary. I was very pleasantly surprised. I'd been saving paychecks for a month or so, anticipating a trip to Bellflower Transmission for repair work, but it looks like a $1.25 resistor did the trick!

Joem, try it. If you have a trans temp gauge, like I do, you don't really need the in-line temp sensor.

halfpint23

Robert Rausch, can you (or some other helpful person) point me to what wires/where in what harness this 1000 ohm resistor is put? Got a VERY similar issue with a brand new transmission - couple hundred miles, and wham, no OD.... Shop that did the tranny work had it for a few days, tested all components, put in new governor solenoid, and said it's gotta be wiring....

Now that I have the 97 dooley fixed, it's on to figuring out the 96 FB!

Robert Rausch

Crawl under the truck halfpint, and see where the stock temp sensor is located. It's in the cooling line a few inches after the line comes out of the trans on the driver's side, on my '95. Then I cut off the electrical connector that originally connected the wires to the sensor. I just stripped back the wires a little bit, and soldered one end of the resistor to one wire and the other end of the resistor to the other wire. I taped each splice individually and the taped them together and tucked the spices out of the way. By the way, I now have 15,000 miles on my "fix" and everything still works great.

halfpint23

Thank you! So really that simple? Using the resistor to bypass the temp sensor? if I am reading you correctly - cutting OFF the two-wire harness and resistor is now replacing the assumed deadbeat sensor.

Secondary thought - if a pyro gage is then installed does it read from the same sensor or is it tapped into a line someplace else? This particular truck pulls heavy stuff for a living and I hate to use the "smoke appearing" method of knowing something is not quite right.

dslpower

Pyro sensor is in exhaust manifold. No connection with trans sensor.


An aftermarket Trans temp sensor is usually installed thru the pan.

Robert Rausch

Yep, it's that simple. The stock trans temp sensor comes into the cooling line at a Y fitting as I recall. It's 4-6 inches or so from the side of the trans. Just snip the wires and solder the correct resistor in-line.

As dslpower states, the stock trans temp sensor has no connection with the pyro. I do have an aftermarket temp sensor installed through the pan, so I can monitor trans temps that way. If you don't have an aftermarket temp sensor, it would be good to get one if you do this fix.

halfpint23

Robert RAusch, as I am electronically challenged to say the least - I'm finding a LOT of variety when I search for "1000 ohm resistor". Is this a fussy thing, as to voltage etc?
For instance, this heading:
1000 ohm / 1K - 2 watts 2W - 5% - Carbon Film Resistor

Bug body on a long skinny wire to me stripes are offset - indicating flow + to - ?
I need a better/younger brain.

patdaly

Stripes tell you Ohms and precision, resistors can go anyway.

That will be plenty good for your use, heck a 1/4 watt should do the trick.

halfpint23

Thank you PatDaly Now if it will just quit raining again, I may feel more like tackling truck number two. I am frankly getting too **** old to be crawling under trucks....

Robert Rausch

I got the 1 watt. I figured with all the gremlins in the electrical lines for the trans, a little safety margin wouldn't hurt anything. I got mine at Radio Shack.
The wattage only tells you how many watts it is rated for (before it blows). The stock trans sensor is certainly rated at less than 1/4 watt, but getting one rated for more is just fine.

1workinman

Glad you got the problem resolved. I replaced my temp sensor years ago with a resistor and never looked back. You have seen the video on u tube about how the rebuild the tps switch bracket . Worn out bushing ect . The extra movement on the tps can cause problems also Jim