4L60E trans/'98 'burb: Does it know when brakes are applied?

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4L60E trans/'98 'burb: Does it know when brakes are applied? Group: alt.autos.4x4.chevy-trucks Date: Tue, Sep 30, 2003, 10:50pm (CDT+5) From: snipped-for-privacy@y.z ((Pete=A0Cresswell)) Seems like it either downshifts or the torque converter locks up almost all the time just after applying brakes - no matter how softly - when in "2". I like this....but it raised the idea that maybe the transmission's program gets input from other parts of the vehicle - like brakes and maybe the engine. That being the case, it would seem like there should be various different transmission programs or parameter sets available to suit various driver preferences. One thing I'd like is a stronger, faster lockup when accellerating - sometimes I get caught coming off an on-ramp when the thing just sort of whirrrs - like it's between gears - instead of grabbing..... Also, I'd like to see the lockup upon braking become something like a lockup as soon as one takes the foot off the gas.

Have I been drinking too much coffee again

when in 'OD', the input sprag freewheels whenever you let off the gas

when in 1,2 or 3, the 'over-run' clutches are on, effectively locking the input sprag and causing engine braking when you let off the gas

it should *unlock* when the brakes are applied. there is a set of contacts built into the brake switch to interrupt power to the TCC solenoid.

locking up with brakes is a bad thing..... kills your engine when you stop. your trans is integrated with the engine in the PCM... it takes input from many sensors to control shifting.

in theory, you should be able to program significant changes to the trans's shifting to a point.... the E is still somewhat hydraulically controlled. I think the only completely electronic truck trans is Ford's Torqshift.

lockup isn't what you want, lockup eliminates the wonderful torque multiplication of the torque convertor... I can't get into the specifics (as I don't know them) but the lack of "go" I would attribute to apply timing. to get the function you want, put it in D and kiss your mileage goodbye. the tranny freewheels in OD when you're off the throttle, saving fuel.

-Bret

how ?

it's the part of ROM programming in the ECM

if you're smart enough to hack the PCM.... burning a new ROM shouldn't be too hard.

like I said.... In theory.

-Bret

controlled.

It will engine brake in anything but OD. When caught in heavy stop/go traffic I will shift down to 3rd so I can get good engine brakeing and a smoother ride rather than gas/brake/gas/brake/etc. Odd thing though if I shift to 2 mine starts out and stays in 2 it won't shift down to first even when I come to a complete stop.

yes

that is part of the programming of a 4L60E

similar to a C6......put the selector in '2' and it wil start and stay in

2nd

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4L60E trans/'98 'burb: Does it know when brakes are applied? Group: alt.autos.4x4.chevy-trucks Date: Tue, Sep 30, 2003, 10:50pm (CDT+5) From: snipped-for-privacy@y.z ((Pete=A0Cresswell))

Seems like it either downshifts or the torque converter locks up almost all the time just after applying brakes - no matter how softly - when in "2".

I like this....but it raised the idea that maybe the transmission's program gets input from other parts of the vehicle - like brakes and maybe the engine.

~~~RANDOM THOUGHT now on topic~~ That being the case, it would seem like there should be various different transmission programs or parameter sets available to suit various driver preferences.

One thing I'd like is a stronger, faster lockup when accellerating - sometimes I get caught coming off an on-ramp when the thing just sort of whirrrs - like it's between gears - instead of grabbing..... Also, I'd like to see the lockup upon braking become something like a lockup as soon as one takes the foot off the gas. Have I been drinking too much coffee again

----------------------- PeteCresswell

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looky there.......

more questions.

Pete, yes you can change the shift strategy. By using an aftermarket "in-line" harness adapter made just for the purpose. Contact a good tranny-shop for a local price on the installation.

Scrib Abell ~~answers the questions asked~~

RE/

Good catch. -)

----------------------- PeteCresswell

Why did they do it that way. Here the highways slow down enough that I have shifted into 2 to creep along but when we do stop it takes more effort to get started since it doesn't shift to 1st.

I'm not sure

perhaps to give you a 'snow' gear to start without spinning ?

"Gary Glaenzer" sez:

Yup, a poor man's traction control.

VLJ