Torque Converter Never Engages

[ns87]

4T60

 

In my 4+ years of ownership, I've never felt my torque converter kick in. At highway speeds I can lightly tap my brake pedal,and the RPM never changes (aka the torque converter disengaging) The TCC plug is plugged in.

 

I'm going to clean the contact points of the plug, but what else? I know sometimes the TCC will mess up on other cars causing bucking and what not, but can the TCC be completely dead and just never engage?

 

The reason I bring this up is b/c at 65mph I turn about 2500-2600 RPM. Is that a little high?

[birdman]

The tcc can stick and never engage and you wont really notice except on the freeway, and 25-2600 is high, should be very close to 2k at 65. sounds to me like you need to check all the wiring and if thats not it replace the tcc. Ive heard its a real PITA to do.

[ns87]

Anyone have a diagram or at least know where the wires are going?

 

I've found this thread so far, but that's about it:

 

http://www.w-body.com/forum/index.php?topic=65624.msg810936#msg810936

 

Gonna go out and check the connector right now

[89SupremeCutty]

at 65 im usually between 2000 and 2500.

[ns87]

Ok did a "controlled" test

 

Connector not plugged in

 

2k RPM -->51mph

 

I turned around and drove the same flat stretch of roadway again

 

Connector plugged in

 

2k RPM -->51mph

 

Light tapping the brakes did not budge the RPM either time. Its raining hard now, so maybe tomorrow after work I'll get some Dielectric grease for that connector. Nothing is oxidized, and none of the wires are broken (that I could see).

 

Is the connector attached to the transmission supposed to spin at all? Mine can spin about 1/5 of a turn.

 

Thank you all. I'll keep this updated

[Crazy K]

the 95 that i sold my brother... just had it's TCC fail.

 

why does that happen? CS1138's 95 GP did the same

[jmoore4294]

I believe mine may be failing as well. Cruising at highway speeds, my rpm's jump from 2k to 2500 or 2600. It's quite intermittent though. It might even go back to normal rpm's every now and then after jumping.

[Brian P]

the '95+ fails more commonly due to the PWM solenoid failing. That solenoid simply softens the TCC apply, and when they fail they block the signal to the TCC solenoid. If you cut the PWM signal (black wire) it will usually allow the TCC to operate (though it will be VERY firm)

 

Now the '91 when you say 2500-2600 rpm @ 65mph, does the rpm "vary" with the throttle? The rpm will be consistent when the TCC is locked up, meaning for example, you're cruising 60 mph in OD, when you come upon a slight hill. When increasing the throttle, the rpm speed will not change (unless your vehicle speed changes). With TCC off, the rpm will increase quite a bit on that incline, say from 2000 to 2500 rpm. I just want to be sure it's your TCC that's bad and not your OD gear.

[ns87]

I think '91 you mean me? I'm '90

 

No matter what gear I'm in, the RPM will constantly change depending on the gas pedal. No "torquing" as I call it. If I'm doing 75mph, I can depress the gas slightly, and have the RPM change instantly.

 

**edit**

 

Just wanted to say, this is not a drivability issue. If Joe Schmoe test drove my car, they wouldn't notice the difference. I just always found it odd that my dad's 3 speed automatic had a noticeable torque converter engage, and I couldn't ever get mine to.

 

Plus my MPGs aren't that good considering I drive like an old man.

 

BrianP, if you know where the wires go I can trace them out and see if any of them are broken. I saw the loom they were in running across the front of the engine down by the coil packs. Could a frayed/broken wire cause it to never engage? Or would that just make it erratically engage?

 

Thank you!

 

 

[shyguy164]

Mine'll lock in when I'm in OD and it wont let go! I can never coast down.

[Brian P]

yeah a broken wire could cause that. I meant '90 there used to be a lot of red Cutlass sedans on here.

 

A '90 4T60 you need to look into Pin A (red) and Pin D (black) on the main transmission connector. The red wire gets power in run, and will cut off when the brake pedal is applied (failsafe TCC disengage). Pin D is a switched ground controlled by the PCM, this is how the PCM controls its function. Check for power at Pin A, if you're not getting anything, you likely have a bad brake lamp switch at the pedal. If you do, the next step is to verify the PCM is giving the ground signal. This involves running test leads to a multimeter that you'll keep in the car while driving. If none of these tests show a problem, it's likely the TCC solenoid has failed and needs to be replaced, which is a bit of work on the 4 speed.

[1990lumina]

Does your cruise control work? Maybe your brake switch is not adjusted properly and thinks the brakes are on all the time - are your brake lights constantly on?

[ns87]

yeah a broken wire could cause that. I meant '90 there used to be a lot of red Cutlass sedans on here.

 

A '90 4T60 you need to look into Pin A (red) and Pin D (black) on the main transmission connector. The red wire gets power in run, and will cut off when the brake pedal is applied (failsafe TCC disengage). Pin D is a switched ground controlled by the PCM, this is how the PCM controls its function. Check for power at Pin A, if you're not getting anything, you likely have a bad brake lamp switch at the pedal. If you do, the next step is to verify the PCM is giving the ground signal. This involves running test leads to a multimeter that you'll keep in the car while driving. If none of these tests show a problem, it's likely the TCC solenoid has failed and needs to be replaced, which is a bit of work on the 4 speed.

 

Will look at this more in detail after work today!

 

Does your cruise control work? Maybe your brake switch is not adjusted properly and thinks the brakes are on all the time - are your brake lights constantly on?

 

Funny you bring this up. My brakes lights are not always on, and my cruise control works (kinda). It seems to lose about 1~2 mph every couple minutes after I engage it. I then have to speed up and reset it. Keep the ideas coming guys,

 

 

I'm gonna check on up all of them!

[Crazy K]

the '95+ fails more commonly due to the PWM solenoid failing. That solenoid simply softens the TCC apply, and when they fail they block the signal to the TCC solenoid. If you cut the PWM signal (black wire) it will usually allow the TCC to operate (though it will be VERY firm)

so 94 has a different pinout??? can you lead me to a diagram of the 95 plug?

[Brian P]

I can't remember fully but I think the '94 and '95 w-body trans connectors are the same.

[Brian P]

Oh, diagram:

 

[Crazy K]

me love you long time! (thanks)

[Dark Ride]

the '95+ fails more commonly due to the PWM solenoid failing. That solenoid simply softens the TCC apply, and when they fail they block the signal to the TCC solenoid. If you cut the PWM signal (black wire) it will usually allow the TCC to operate (though it will be VERY firm)

 

Now the '91 when you say 2500-2600 rpm @ 65mph, does the rpm "vary" with the throttle? The rpm will be consistent when the TCC is locked up, meaning for example, you're cruising 60 mph in OD, when you come upon a slight hill. When increasing the throttle, the rpm speed will not change (unless your vehicle speed changes). With TCC off, the rpm will increase quite a bit on that incline, say from 2000 to 2500 rpm. I just want to be sure it's your TCC that's bad and not your OD gear.

you mentioned this in another thread and I just wanted to let you know that cutting the black wire fixed my problem on the lumina and now makes highway driving bearable in the lumina, although I still haven't figured out why I have no OD.

[Crazy K]

my problem fixed

 

btw, I've had the loss of overdrive issue in both the 94 and 95 CSs... it seems to be tied to overheating of the trans... due to lack of decent tranny cooling. When this occurs... I simply turned the key off, and right back on and the pcm would reset and O/D would return.

 

Both cars had thin 1/2" radiators.

I added a trans cooler to the 95...

and I upgraded the 94 to a 1-1/4" core radiator from a 94 LQ1

both cars have been problem free since. I will be upgrading the 95's radiator as well soon, too.

 

 

And Brian, I believe the 94 car with the tranny coded CMW, which is the W-body tranny that lacks the PWM solenoid, was probably used only in 3.1MPFI 1994 Luminas. My 94 had a black wire in slot C, and I cut that one too, to see how it responded.

[Brian P]

yeah, figures, that PWM solenoid is VERY problematic. It went bad and caused issues with my car's original tranny, as well as failed on my mom's old '95 Cutlass she had since new.

 

I don't really hear of these issues in the later 4T60e's as well as the 4T65e's so it must have been a bad (early) batch.

[ns87]

Well StylesP,

 

I bought a multimeter. 4 of the 5 wires on the TCC connector had voltage running through them while the car is on.

 

It's been a while since Physics class and I forgot how to use an analog multimeter. The "1 A/C" setting had the needle pegged instantly, so I quickly put it on the "10 A/C". 6 volts? Does that sound reasonable? They all had the same readings.

 

The 5th wire had no volts, so I switched to resistance mode. That wire was dead on 2 ohms.

 

I got some dielectric grease and contact cleaner and went to town on the plug and connector.

 

----------------------------------------------------------

On to highway test:

 

Today: 2k RPM ---> 55-56mph

Yesterday: 2k RPM --> 51 mph in bad weather

 

Today :2500RPM --> ~70mph

 

The car has significant "push back" at 2500RPM. But the RPMS still vary freely with the gas pedal. And hitting the brake pedal does not raise the RPM at all

 

SO, my next question. Do I just run a wire from the multimeter inside to that one which had resistance? Then drive and see if the resistance changes?

 

Lots of words, but thank you for reading!

 

[Brian P]

check for DC voltage. The 3 other wires you tested are 12V outputs to switches that tell the PCM which gear it's currently in. The last one is a ground, for the TCC solenoid.

 

That wire would be the one you'd check if it's being grounded while on the highway cruising. This may help you as well to give a visual: