P0740 and transmission acting wierd, went away at the shop..

P0740 and transmission acting wierd, went away at the shop..

Postby thesigma [OP] » September 16th 2020, 3:59pm

So a couple weeks back I jumped in the van to go to lunch, and it started doing this wierd shuddery thing at low speed, so I turned around and parked it at the office. Ran my little bluetooth OBD and Torgque app and pulled a code P0740 TCC circuit failure. tried to drive it again later and the same thing and it didn't seem to shift... left it sit a couple weeks as I had to go out of town and when I got back I started looking for a new ride and got a pre approved loan for the payment I was willing to have (but don't really want). looking around and not finding instant gratification, I called The local transmission shop and talked to them. They said theyd check it out and worst case about $2200 installed for a rebuilt tranny and I said I'd think about it. ended up driving it down a couple hours later after deciding I'd rather put another 2200 in the van. It does have 240K miles on it but in the last year and a half (and 20k miles) It has a new fuel pump, 4 new shocks, 4 new tires, and a rebuilt front end, I've maintained her faithfully since I owned it at about 88K miles, and it's been a really great vehicle. on the other hand I don't require the moderate offroad ability and cargo space anymore and it's not so good on gas as a daily driver. Ultimately I probably find a cheap little japanese beater to drive to work everyday (~10mi. no highway).

Anyway the shop calls me up yesterday (I dropped it off the prior night) and says now what exactly was the probelem because it seems to be working normally. No when I drove it over there it was worse than ever, I backed out of the parking spot fine but when I shifted to D it didn't want to go, had to give it a lot of gas to get going, and it shakes real bad at low speed up to about 30 MPH or so then when you brake it doesn't want to decelerate and starts shaking when you stop. I guess it was the torque converter clutch staying locked? it was maybe 2 mi from the office to the Transmission shop, so all told I dove it maybe 5 miles acting wierd.

They pulled the pan and asked when I had it serviced last. Fluid and filter about 6 months ago IIRC. said it looked great inside, but after talking more about the problem they still think it's on the way out and I"ll need a rebuild. I decided to drive it for now and see how it goes (won't be making any long trips in it). so far so good, drove it home and back to work this morning.

Read all 9 post's that caome up with p0740 in the search, seems like some people had it caused by electrical problems, but usually got other codes with it. I don't other than an evap solenoid code I've had forever.... they had a better scanner at the shop and said they got only those two codes also and the temp and realtime info looked normal. I also read about ignition switch causing some problems but that seemed different than my issue. I only wonder because I did have to replace my worn out lock cylinder (but not the switch) about 2 months ago.

Also my Headlight Auto on feature will quit working for sometime a couple times, both times it started working again after a trip to the shop.....(and no it's not the press the button 3 times till it chimes thing, I knopw about that and it wouldn't engage the feature at all)

I mention it because I want to rule out the possibility of say a bad ground or electrical problem that a rebuilt transmission wont fix. I hate wasting money......

Any thoughts?

Thanks!
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Re: P0740 and transmission acting wierd, went away at the sh

Postby MechBob » September 16th 2020, 4:17pm

It is possible the wiring harness to the trans,or the one in the trans,has a spot rubbed in it,causing an intermittent problem,but they should have inspected them,as they had pan off and vehicle up in the air.I would have replaced the TCC solenoid,at that point,if I found nothing.As,many times,it is dirt in the solenoid,or it is failing.Will leave you 2 articles to read.
https://www.obd-codes.com/p0740
https://www.onallcylinders.com/2019/04/ ... converter/
Oh,yes,what you describe is the tcc being locked up when it should not be.
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Re: P0740 and transmission acting wierd, went away at the sh

Postby thesigma [OP] » September 16th 2020, 5:49pm

Thanks MechBob.

So the solenoid looks like a cheap part. not sure I want to drop the pan and do it myself though, I don't have a lift and it sounds messy. I can understand a shop not wanting to do it either b/c it seems to me at nearly 250K miles, something else may go at some point.....

What do you think? I'm willing to put say 200 or so dollars in to trying with no warranty. but shopuld I expect much more life out the Tranny with that many miles? or should I just bite the bullet and replace with a rebuild?
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Re: P0740 and transmission acting wierd, went away at the sh

Postby MechBob » September 16th 2020, 5:53pm

Not going to make a recommendation.bad practice.BUT,my 96 has 211,000(or more),original trans,and if just the TCC was acting up,I would be trying the repair. :D
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Re: P0740 and transmission acting wierd, went away at the sh

Postby thesigma [OP] » September 20th 2020, 4:45pm

So it started acting up again Thursday and I parked it at home. not nearly as bad as before it just felt like the tourque converter clutch would stick a little then let go. I'm going to attempt to replace all the solenoids and wiring harness (looks like
I can get an electronic parts kit for about $200). anything else I should look at or replace while I'm in there? I'm only dropping the pan so I'm not going any deeper than that, and I don't have lift so I really don't want mess with the valve bodies unless I have to. The 1-2 shift isn't terribly smooth but hoping the solenoid might help? need to order parts soon to try and do the job next week.

Went and picked up a 2012 Toyata Camry with about 89K miles on so hopefully we have at least one reliable car for the next couple years....
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Re: P0740 and transmission acting wierd, went away at the sh

Postby thesigma [OP] » September 25th 2020, 3:20pm

Parts are here...I'll report back how it goes. Looks like a messy job so not sure about photos.
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Re: P0740 and transmission acting wierd, went away at the sh

Postby AstroWill » September 25th 2020, 4:53pm

thesigma wrote:Parts are here...I'll report back how it goes. Looks like a messy job so not sure about photos.

Take it slow, those huge $12 transmission drain pans from WM help, I also put one of these under the transmission drain pan https://amzn.to/33YRS9V they used to carry them at my WM but the LAPS have them as well, same price. Don't remove all of the bolts at first gotta let it drain a bit. Don't need a lift, just some jack stands or ramps.

Good luck and let us know how it goes!

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Re: P0740 and transmission acting wierd, went away at the sh

Postby Rod's Trucks » September 25th 2020, 7:14pm

If you can function with oily wrenches and sockets, you can do it, even laying on your back.
I always find large cardboard box to flatten out. It provides some cushion and is easy to slide on, if you don't have a creeper.
I speak from experience...
Get a bag of 'Kitty-Litter" and a wad of rags or paper towels! Having them handy may preclude the need for them.
I once did a great clean job of an oil and filter change, on my VW diesel Jetta. Oil changes on a diesel are the worst, becasue the oil always commes out BLACK, and stains everything it touches. I managed to trip on something with the pan of waste oil and dumped it all over the garage floor. It made a much bigger mess than if I had just pulled the drain plug and tried to catch it in an antifreeze jug....The nearby bag of Kitty-Litter allowed me to build a dam around most of the spreading oil, but it still took a long time to get the mess cleaned up.
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Re: P0740 and transmission acting wierd, went away at the sh

Postby thesigma [OP] » September 28th 2020, 3:46pm

So I Seem to have it fixed and never had to drop the pan. When I got under there and started looking around, and trying to find the transmission wiring to disconnect from the plug, the black corrugated wire tube started crumbling in my hands...Enough fell off that I could then see a wire that had rubbed bare against the transmission case, which is grounded and so shorted the Circuit. I pulled the connector and flopped everything over t o the opposite side of the transmission to get as much length as possible. Cut out about 2" of said wire and stripped each end back, nice clean shiny copper so I soldered in a 2" replacement piece, heat shrink tube over it, tape over that, then spiral cord wrap around the whole bundle, corrugated split-loom over that and taped the split loom over for good measure....Re-installed and so far so good. Also pretty sure My evap code is coming from faulty wiring, moving crap around down there made the vent solenoid start clicking like crazy....unplugged it for the test drive. tried to troubleshoot the next morning and no dice. the constant +12V is there, so it must be on the computer side so thats gonna be a hell of a time troubleshooting. suppose If I could figure where that wire goes and replace the whole thing....Would be nice to have the MIL Stay off.

So anyway, I knew it was an electronic problem.... Lets see how long it holds out. she shifts as good as well it did before the trouble.....which is good enough for me. No longer a daily driver anyway.

Thanks as always for the guidance. sooner or later I will probably have to drop the pan....
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Re: P0740 and transmission acting wierd, went away at the sh

Postby Mmusicman » September 28th 2020, 4:35pm

thesigma wrote:..Enough fell off that I could then see a wire that had rubbed bare against the transmission case, which is grounded and so shorted the Circuit...

Excellent discovery! Look how much money you saved! Awesome! :thumbup:
That transmission shop was all set to take BIG money from you for a simple wiring repair.

My 2000 had the same issue with shorting wiring at the switch .. it was repaired as well. :D
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Re: P0740 and transmission acting wierd, went away at the sh

Postby thesigma [OP] » September 28th 2020, 5:29pm

You know I wondered if they really just wanted to sell me a transmission but to be fair, I don't think they would have ever found that bad wire from a lift. Only because I was laying on the floor on my side looking sideways could I see it.

I'm pretty sure they dropped the pan because they asked me how long ago it was serviced they could tell the filter and fluid were still very new (answer, less than 6 months)... Then again they insisted the code was not due to an electrical problem, but everything I looked up said it was, or the solenoid was actually bad, still an electrical problem.

There's a reason I do almost everything I can on my vehicles but I draw the line at jobs needing a lift (or that take significantly more time without one. I'm not as young as I used to be and have developed a bulging disk in my neck and after fifteen minutes under the van I had to come out and give my neck a break... I need a shop pillow next time so I can prop my neck up where it needs to be without straining the muscles....
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Re: P0740 and transmission acting wierd, went away at the sh

Postby AstroWill » September 28th 2020, 9:41pm

thesigma wrote:So I Seem to have it fixed and never had to drop the pan. When I got under there and started looking around, and trying to find the transmission wiring to disconnect from the plug, the black corrugated wire tube started crumbling in my hands...Enough fell off that I could then see a wire that had rubbed bare against the transmission case, which is grounded and so shorted the Circuit.


That is awesome! Glad you found your issue and thanks for posting your solution!

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Re: P0740 and transmission acting wierd, went away at the sh

Postby thesigma [OP] » September 29th 2020, 3:14pm

I always try to post the resolution (even if it's not a solution). It's helpful and I hate when I'm Searching for a problem and I find a dead post with the problem and no updates....

Wasn't a lot of info relating to that code on here so theres a couple possible solutions in this thread and then there's my actual solution. Glad it was fixed and we really needed a second vehicle anyway, so still glad we picked up the Toyota Camry for a good price.

And as always so glad this forum is here.
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