430 F1 Transmission - P1741 code

Wanted to update this since it has been a week or two of troubleshooting with a lot of help from flash32. (Summary is the problem is still happening).

- Had battery load tested. It is fine per Interstate (2 yr old AGM).

- Lots of sensor checks and watching the voltage of the battery with car on/off and after it sits. We did find the alternator seems to be a running a bit low based on what I have seen with other cars. Running voltage with or without accessories on seems to be around 13.6-13.9 volts.

- F1 pressures are holding well / good leakage rates.

- P1741 cleared on its own the first time after sitting for a few hours and I was then able to shift again.

- Unable to repro error in the garage. Able to cycle through all gears with Launch. Dash reports correctly.

- Finally took out to try and repro. After about 15 min of driving and getting coolant temp up to around 90c, transmission light came on I was unable to shift from 4th to anything besides N. Coasted to a parking place (luckily). Tried to clear the error, but it was still active. It would let me get into R, but nothing else. Not wanting to get it towed again, I let it sit for 2 hours and came back. Fired right up and error was gone. Able to drive it home normally.

I did get a recording with the Launch of when it happened, but I am not sure how to interpret the values returned by the F1 potentiometers. It was showing the TCU calling for 3rd gear, but it never left 4th when it happened. Voltage seemed to be steady the whole time, but hard to really know given the launch refresh rate.

So next steps, unless there are other ideas, is to pull the actuator and inspect the pots, possibly replacing them (on order). If I notice any fluid leakage on that end, I will probably have the actuator rebuilt by GTE.

@flash32 - Anything else I am missing?

 

So I pulled the actuator today and popped out the sensors. They are covered in what looks like a thick grease. This seems odd to me, since there is no mention of any grease in the WSM nor the prior thread @mwstewart posted. Does anyone know if this is normal, something leaking from inside the actuator, or an over-zealous mechanic (no idea if it has ever been opened up prior)?
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That's interesting. I'm thinking of cleaning it up, replacing the sensors with new ones and seeing what happens. What's odd is there isn't anything in the docs that mention using a grease at all.

 

Well hopefully this will be the final update… I replaced the F1 sensors, cleaned out 90% of the grease I found in there and put everything back together. Did a re-learn with my launch before starting the car and that procedure completed properly. I was able to shift through the gears using the launch and the dash matched up correctly.

So…Finally had time and a clearing in the weather this AM to take her out and it seems that the shifting issue is resolved with the new sensors.

One note is that before I did the relearn, when I would use the launch to cycle through the gears while the actuator was off the transmission, the dash would occasionally show the incorrect gear number. I suspect this was just due to having not done the re-learn yet, and I didn’t want to do that with the actuator off the transmission.

Of course, in the process of putting the cat back on, something wasn’t lined up correctly with the header/donut gasket so I had an exhaust leak. Took it apart and then managed to break one of the welded bolts which mount the muffler to the exhaust flange. A trip to a local exhaust shop and $60 solved that issue (just ended up using a new bolt and nut once the broken on was removed). Once all back together, the leak was resolved and everything seems good so far.

Also interesting - Serkan @ GTE called me yesterday and said there should be a reasonable amount of molly grease or similar in there and it is not documented since it isn’t considered a user-serviceable part. His thought was that whomever put that together may have had a rough night and was distracted Not sure it could cause my issue, but probably didn’t help.

And a pic since she got a much needed bath before the rain comes back tonight.

Many thanks to those who have helped me work through this, especially to @flash32. Dominick has been my biggest supporter and I am grateful to call him a friend.
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I had that thought… but this was a $500 fix and not 30k

 

@Jackson32 Sorry to hear you are having a similar issue. Mine actually wouldn't even really go into limp mode - when it was at its worst I was left with R and N until I let it sit for a few hours.

I would definitely make sure you have a solid battery which test to 12.6 volts when the car is off and comes back after a load test.

Do you have a tool like the Launch to read the codes and monitor voltages as well as the signals coming from the potentiometers? I would be curious to know what code(s) you are seeing.