4L80 DTC 73 pressure control solenoid with fix

Vehicle is new to me, never operated, engine had been swamped, not swapped, swamped, assuming hydrolocked,



sat for years and years, odometer showed 400 miles til towed home, now almost 700, everything looks brand new, foil tape still on all openings. Has data plate for Navy fire fighting foam system, swamped engine now runs..... anyways back to the story....
drained fluid, looked very good, bright red, no water, no black floaters,
missing tcm so installed Used tcm, fault light on, no flashy from light when put in service mode, ordered different tcm, now shows dtc 73 when put in service mode, power is correct, started and ran 100 yards, shift from 1-2 then limp mode, code 73, ohms at tcm j1 to test pressure control solenoid (pcs) within posted limits, 4.7ohms,
no oil in trans j1, clean, tight connection
drained new oil, dropped pan, pan clean, tested pcs with wiring disconnected, still 4.7ohms, hear a click when plugging and unplugging,
pulled pcs from body, looked new like everything else, no fm on screens, bench tested with 10v, clicks when power is applies.
installed new pcs, bench tested 4.9ohms, tested ohms from tcm plugs, 5.7ohms, not within limits, but i am also testing from the maximum distance.
Any other suggestions other than another tcm

Are you working with Supplement 7. Do either of the PCS solenoid wires show continuity with ground. Is there ATF in the Deutch connector. The usual suspects.

NDT said:

Are you working with Supplement 7. Do either of the PCS solenoid wires show continuity with ground. Is there ATF in the Deutch connector. The usual suspects.

Click to expand...

Yes using sup 7,

i verified, not going to ground,

no atf in transmission j1 connection, clean like new and tight.

reverified ohms at tcm j1, 4.9ohms. when i get more time i may check the tcm box external plug to internal plugs, seems high to have 1 ohm in a 4" of wire and 2 plugs.


if a mod wants to combine this thread with this one, since they are the same fault, i am good with that . https://www.steelsoldiers.com/threads/4l80e-pressure-control-solenoid.217929/

I agree that 1 ohm seems high and it likely gets higher when the TCM tries to pass 1 amp through it.
Try some De-oxit on the contacts.

Mogman said:

I agree that 1 ohm seems high and it likely gets higher when the TCM tries to pass 1 amp through it.
Try some De-oxit on the contacts.

Click to expand...

Is it deoxit that has a rubber feeling after it dries? i already have electrical cleaner that i was going to try, it also may have been the probes i was using to back probe the plugs, i will double check it all

Cleaned connections with electrical cleaners, retested at interior tcm connections, 4.4 ohms on c15-d16.
I also tested the other 3 solenoids, all with ohm limits posted in sup7
Test drove, shift from 1-2 then went to safe mode. Still have same dtc 73,
i am guessing the 2nd tcm is inop as well, open to other suggestions or troubleshooting options before spending $$ on another tcm

Went for a test drive after disconnecting batteries, same story different verse same as the first, shifts 1-2 then safe mode, so i turned off engine while rolling at 30, restarted in N, then shifted to OD, truck shifted to 3rd then acted like tranny was slipping, let off gas, shifted to 2 accelerated shifted to 3rd and slipping, stopped at shop, pulled codes, DTC 39, 73, 86, 87. Pulled battery cables, checked fault code before starting, guess what...... never even started vehicle, DTC 73.

swapped in a 'controlled exchange' tcm from freshly purchaced vehicle, DING DING DING, everything work as designed, so its always nice to have a spare to try,

so I think I have a bad tcm