First I want to acknowledge I have limited ( No ) experience with computer-controlled lockup transmissions.
About a year ago I rebuilt and just got it on the road this week a 4l80E with stock internals , with all new pump, bushings. Stock valve body with a Shift Technology products shift kit. New torque converter from can't remember where.
All is well except it throws a P0894. TCC solenoid clicks on and off and has 11 Ohm reading. It would appear I have to drop the tranny and find my problem. To get to the tranny from my hot rod I must remove engine and pull tranny from front of vehicle ( that's the only way)
My problem is I won't find the time to do this until fall at best.. This vehicle only gets used around town with stop-and-go traffic, and maybe runs 15 minutes if I ever get on the highway.

I want to know if I can find a way to still operate this car without damaging the TCC by simply not engaging it. ( If it don't engage it don't slip, right? )

I have two transmission coolers, one inside the large stock 2500HD radiator and one large plate and fin transmission cooler mounted on the face of the radiator.

Question : Can I disable the TCC solenoid by pulling its pin at the PCM connector and substitute a 17 Ohm resistor ( that's one I got close to 11 Ohm ) then run the other end to the same power source ( ign O ) from TCC solenoid ?
When the PCM calls on the TCC, it will see a resistance, but the TCC will not activate. There won't be any slip and thus no trans-slip-counter to draw a MIL. Any venture onto a road that will call on TCC activation will be brief , maybe 15 minutes at most.

Question: My TH350 in another old hot rod has third gear at 1:1 ( no lockup). Can I run this 4l80E on fourth gear ( 0.75 :1) on the highway without shifting to TCC lockup for those 15 minutes of highway time without damage ?
should I also disable the fourth gear overdrive too, for some reason ?

This idea is just a short term workaround to allow limited function for this vehicle until I get a game plan, time and parts sorted out.

Your thoughts on how stupid an idea this is would take me out of my misery, and would be greatly appreciated.

Thank you very much.


2500HD 4X4 chassis LQ4 4l80E Full-size factory radiator with large plate and fin secondary trans cooler.

 

Your engine will tend to die when you apply the brakes coming to a stop. It will also take extra effort at the brake pedal to make the vehicle stop if the TCC stays engaged. Operating in this manor is not safe for you or others.

Rick

 

Thank you but I am here to find out if I can can operate the transmission with the TCC NEVER engaged.

 

Yes.
The original question " Is it SAFE?"
Yes.
You can run overdrive without TCC lockup commanded.

 

Than you.
Good news I can leave call for overdrive to the PCM. That will be my highest gear for the 15 minutes I'm on the highway.
I'm trying find any reasons the call to activate TCC with no actual lockup occuring will cause any damage to trans or PCM issues.
I'm not concerned about loss of gas mileage. Mr. AI/Google indicated increase in trans temperature, if true I'm curious why.

 

The trans will run hotter in overdrive due to increased load on torque converter over 3rd gear (1:1 gear ratio).

Also, I don't think install a resister in place of the TCC solenoid will spot the check engine light from coming on. The PMC will still see that there is slippage in the torque converter.

 

Trans temp increase is caused by the converter slip in 4th which of course would vary with rear ratio, load and converter stall rpm and where it stands at highway speed. Any engine motion that does not make it to wheels is heat when it comes to the converter. This can be considerable with higher stalls. Just recently had a guy seems a rat or something chewed wires to the TCC for a 700r4 and the result was a mountain drive towing in 4th that supper heated the converter to a point the paint melted off . Have not yet been in unit to see additional damage but suspect ill see melted pump screen and rotor guide at min.

 

Thank you for your input.

Before inserting the resistor in place of the TCC solenoid , I simply de-pinned it from the PCM and went for a ride.
I just got back from a 45 minute highway ride in 85 degree weather. Trans went into fourth when called upon to and stayed there the whole highway run.
Trans temp never exceeded 200 Deg F engine coolant temp. It stayed mostly below that in town.
There was never a command to activate TCC, I guess the computer saw there was no voltage present at TCC solenoid.

When I got back there was no "trans slippage" malfunction code ( P0894) , but there was a new code of "TCC solenoid" malfunction. Duh.
I believe there was a 150 maybe 200 rpm difference from engine speed to output speed in overdrive.

Overall i'm pleased with results as this will allow me to drive this car for an indefinite time until im able to do a proper repair.

Thanks again for taking the time for your observations.

 

Man that sucks, you would think the trans control module would go to limp mode or something with trans oil temps that elevated.

 

E UNITS yes but not 700R4.