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View Full Version : Help with Quirky Transmission Kickdown


Nemo
02-19-2007, 07:36 PM
Guys,
I have read all of the forums concerning the TPS sensor, Throttle cable adjustments and I have turned my FSM into a big bunch of black pages, et cetera. All were very informative but has not relieved my issue.

I have done the acceleration tests provided in the FSM, from you guys online and I don't have a problem with erratic shifting, or not holding gears when they are manually selected.

How I do reproduce this issue is no matter what speed I am going the moment I touch (reiterate just touch - not enough to truely brake) the brake pedal the transmission will no longer "Kickdown" to a lower speed to accelerate. The only thing that seems to resolve my acceleration after that is if I come completly to a halt, and then hit the accelerator again or move the gear selector to 2nd and back to D.

I have checked all fuses and fusible links in great length. To verify this craziness, I have also allowed the truck to come to a slower speed, ie 10mph from 30mph, 50mph to 20mph, 20mph to below 5mph and as long as I don't hit the brakes, I am fine with the kickdown.

I just got through testing in 4 low, ie CDL engaged and ABS off and the problem doesn't happen? ABS speed sensor?

Thanks for your input.

Beater
02-19-2007, 09:24 PM
tranny solenoid.

you heard it here first.

Three Wheel Ben
02-20-2007, 06:26 AM
Make sure your kickdown cable is adjusted properly and not damaged/stretched. That cable controls throttle pressure in the trans. throttle and line pressure work against each other to make the trans shift up and down. When you floor it that cable is pulled and throttle pressure is maxed and overtakes line pressure to make the kickdown happen. When you let off enought for line to overtake throttle the opposite happens - upshift.

It also sound like something may be backfeeding throught your brake light switch. After you've verified that the cable is not your problem, unplug the switch from the pedal and see if it changes.

Also check codes, you may have the famous 83 84 85 codes.

hth

Nemo
02-20-2007, 09:20 AM
Thanks John and Ben,
I have been thinking the solenoid, but trying to exhaust all possiblities before throwing money at it. It is just confusing to think all I have to do is touch the brakes for this to behave this way. I will def. try pulling the Stop Light switch to see if it makes a change. Keeping fingers crossed. Cheaper that way. I think the solenoids run about 170 a piece through American Toyota. Ouch....

Red_Chili
02-20-2007, 10:06 AM
I know NOTHING about auto trannies... but there is a common problem with 22REs and the brake light switch input to the ECM. In some cases the problem is resolved by disconnecting the brake input to the ECM, with no dire results. I have no idea if this is advisable for your truck.

Have you checked with Roger Brown, the tech guy at TLCA?

Nemo
02-20-2007, 11:39 AM
Well I finally got out to troubleshoot the Stop Light Switch. Connects into the Brake pedal under the dash. Pulled the wiring harness to it and test drove. Problem goes away. I will be looking for a new switch and installing it to see if I have a wiring problem or if it is the switch itself. I guess I good do the ohm meter, but I am lazy.

Red_Chili
02-21-2007, 12:00 PM
You just proved that when your taillights come on from the switch, and the ECM gets a signal from same switch, the problem occurs. You knew that. Replacing the switch will do nothing. Clipping the correct wire at the ECM will solve the immediate problem, but I cannot speak to any other resulting complications (if any).

You could carefully trace the wire and clip it near the ECM for a temporary (and possibly permanent) fix, leaving your brake lights functional. Just leave enough to reconnect.

Nemo
02-21-2007, 02:22 PM
Thanks Bill. I have done the voltage check and the Stop Light Switch is def. sending the proper siganl to the ECM, so I am going from there right now. I do like the idea of clipping the wire. It could be helpful to fully isolate the issue. I think ultimately it will hurt because it registers to the ECM to cut the fuel supply / cancel the operation of the lock-up clutch so it may ultimately hurt in emergency braking where the engine is still torquing up??? Any idea on the lock-up clutch?

Red_Chili
02-21-2007, 02:24 PM
That's the sort of problem you see when chasing a shadetree fix such as I proposed. Nope, don't go down that lonely road. Did you check with Roger at TLCA?

Nemo
02-21-2007, 02:35 PM
Not yet. I should go out there to the site and post the question... Trying not to do the shadetree thing yet :-)

BTW. Do you know Rodgers alias so maybe I can send him a private message too....?

Red_Chili
02-22-2007, 06:46 AM
On 4x4wire he is 4Crawler...