ECT Button Ineffective (transmission shift points)

Hello all.

I in need of your help and wisdom. i have a 2002 Tacoma Prerunner with 2.7 Automatic. ECT light illuminates when ECT button is depressed but no change on when transmission shifts. Recently did a new top end do to blown head gasket but it didn't work before either.

I looked for voltage at PWR Pin 17 on E5 connector of ECU when button is depressed using ground from Pin 17 E7 connector. All good there. My question is, what else can i check to ensure the ECU is sending the correct message to the trans on when to shift or anything else i should be checking. Is there other input/outputs i should be looking at? ie.. speed sensor, engine coolant temp sensor etc.

BTW, I'm fairly proficient at troubleshooting but stumped after reviewing the wiring manual and searching this website for a solution.

Thanks in advance for you help.

m

 

Check the relay, and if you have to, drop the pan and do a new filter w/drain and fill and while you’re up in there ohm out all of the shift solenoids theres 3 or 4 in the V-6 auto. The filter and drian/fill will help but knowing the solenoids are working will get you pointed straight. Mileage? The trans may/could use a rebuild, automatics are finicky in all yotas.

 

@gearcruncher

 

lmy, thanks for quick reply.
1.) What relay? I don't see one in the wiring diagram.

2.) Regarding check the solenoids, if the tranny shifts fine in the ECT off mode. Wouldn't that tell me the solenoids are working fine?

As i understanding it, with ECT on (Power mode), the ECU tells the tranny to change its RPM shift points.

Thanks again,
m

 

There should be info in here about it. See pdf

 

I don’t notice much difference other than the OD lockup being at a higher speed when I don’t have a load behind the truck. Once there’s a load, then I feel and see the difference in shift points.

 

same here

 

You can tell when it’s not working right it wont rev each gear longer like it should, towing or not I feel it either way. In normal mode it shifts at lower points when flooring it in ect it takes longer to shift gears because it holds the gear in a lower one for increase in rpm. So what does the trans fluid look like I’d like to see a pic and we can all start from there, ect isnt just computer control of shift points, there are mechanical parts that effect ect too. Hydraulic line pressure will play a role too in these.

 

I’ve had 2 first gens, and I’ve never noticed any difference in shift points other than the OD lockup speed being higher without a load behind the truck. Once you have a load, and the truck’s working harder, I’ve noticed the extended shift points.

Whether wide open in ECT or normal, there’s no difference in shift points. It takes it to red line in either mode.

 

Come bye I’ll give you a ride so you can tell me a liar, I promise it changes on mine does you’re trans need service?,maybe.

 

Btw brand spankin new trans in mine A340 from toyota I installed, last tranny ect was very noticeable w/o towing too.

 

A service won’t make a difference. The shift points are controlled electronically. And my transmissions are in good shape. My current is at 83k miles.

 

Thank you all for the help, i'll get this fixed yet.

Great tranny pdf thank you. Unfortunately no info on relay or shift points with ECT on.
It would appear the ECT works on some while not on others. Mine happens to be the latter.

Trans was service just before i bought it 2yrs ago (previous owner and neighbor).
Still looking for help on how/where ECU communicates to trans on shift points.

One thing to add, i found a fuse 15a position in the fuse/relay box by battery that reads 'ECTS' however there is no fuse and no number 2 contact for the fuse. Going to keep looking in electrical diagrams to see if i can see what gives.

If anyone gets a chance, could you see if you have a fuse and in that position and let us know if your ECT button works or not.. maybe i'm on to something.

Thanks again to you all,

m

 

update, found a wiring schematic that shows pin 2 on the ECTS 15a fuse is a pink wire however i can't find that wire on any other print.

Could use someone's help with above or in general knowledge of this issue.

Thanks,
m

 

@miloaksrider your description says 03 but you say it's an 02?

the ECT function on normal everyday driving will be very "unnoticeable" due to no strain. Even when I was towing an extra 1k on flat ground it would only hold on for an addition 1-200 rpm on the standard 3 gears. O/D is another beast altogether by its nature.

my experience sides with @smmarine on this one even though most of my terrain is hills.

@Luv my yota if yours is holding for extra hundreds or 1k rpm that's not a good sign, or your driving habits/terrain is different from OP. I'm not saying you don't experience what you are, just that my experience is different.

 

Thanks Frizzman.
Good eye. My trunk is an 03 not 02.

A friend came by yesterday. He has same truck (03 prerunner) but w v6. Looked at the ECTS fuse and position. His has the 15a fuse and wire leaving that mine is missing. I did a quick drive but didn't notice any difference w or wo etc on. I'll do some more digging and post on thread.

Thanks again
M

 

I was going to mention but since you have a 2.7L 4 cyl you shouldn't have that anyway.

the V6 in 03 changed to an electronic Throttle Body (ECTS - Electronically Controlled Throttle System or w/e). The same fuse box is used for cost savings

 

Lol, not a good sign, my trans is in perfection condition. Must be the fact that I can feel what most don’t ever. I custom build bikes and car/trucks I don’t believe I asked if my transmission had a problem, because it doesn’t and it operates correctly, trust me. Hey Gearcruncher where you been? He’ll tell you what that button does if you don’t believe me.

 

I know what it does. I have "felt" it also. Never said it doesn't work, just not to the extent you are seeing I guess. Like I said for my case, it will carry it out a little more than normal but not hundreds of RPMs. And that's towing a little over 1,150 lbs (trailer + bike).

 

But to:



If @miloaksrider is not seeing any change whatsoever then there could be a potential issue. Maybe a dry run on some different and inclined terrain to test the theory?