TCC not engaging on a 3T40 Transmission ('91 Pontiac TS SE)

[Meridivs]

It appears that the TCC doesn't engage at all on our '91 Pontiac TS SE. The cruise control works fine but the engine RPM's is noticeably higher than on our other TS's.

Does anyone repaired such a problem or has any info about the TCC Solenoid location on the 3T40 transmissions?

Do you need to disassemble the whole transmission to fix/replace this component?

[Tech II]

Have you checked fluid level and condition?

Drive car manually....1....then 2(feel shift from 1?)....then D(feel shift from 2?).....

Now while cruising with one foot on gas pedal, just lightly touch brake pedal with other foot....do you hear/feel TCC disengage or notice a change in rpm's?

TCC solenoid is in side cover of tranny, but you can't assume that is the problem without proper testing...

[Jrs3800]

I agree don't doom the TCC solenoid yet...

You need to know if you have any codes stored in the ECM, as well you need to scan to see if the ECM is even calling for the TCC to apply...

Like stated above you can do the brake test to see if the TCC is even applied..

[Meridivs]

Thank you for the ideas.

I tested the electrical connector to the TCC and it's having votage (12V)

The TCC doesn't engage at all (any speed above 80 Km/h) on this car - the engine RPM is way too high at highway speeds - almost 600 RPM or more than the other Trans Sport with same engine/drivetrain.

Tech II
Fluid level is ok, maybe the condition is not so great - it's old and mineral. Color is more light yellow than red, no burnt smell or black tint. I plan to switch it to Mobil 1 Synthetic Dexron-III since this car sees a lot of heavy urban traffic.

Transmission shifts through all gears as smooth as silk, barely noticeable. You cannot feel anything when shifting from 1 to 2 to D.

No immediate/noticeable change in RPM's when slightly touching the brake pedal at highway speed. The RPM's drop only when taking the foot off the accelerator pedal.

Jrs3800
I have an ALDL scan cable and WinALDL installed on my laptop. No codes stored so far. I will try to take it to highway while connected to the laptop to see if the ECM tries to engage the TCC but I'm not sure how you can see that.

There's three "Flag Data" in WinALDL that could relate to this condition:
1. "4-3 Downshift for TCC unlock / AF Cold Park"
2. "TCC Locked"
3. "No High Gear"

Any ideas on how can I see if the ECM tries to engage the TCC? Otherwise there's no drop in RPM at high speeds and no change in drivetrain feel.

[Jrs3800]

Generally I think if the ECM tries to apply the TCC and nothing happens it should throw a TCC code... Not 100% sure how the older 3.1 V6 ECM deals with these issues...

Not sure what you have going on... As well what temp does the ECM think the engine is running at? The ECM will not lock the TCC unless it thinks the engine is at a certain temp... I think with your van its 150F before it will lock it...