458 DCT error light illuminated

Starting a new thread regarding my DCT issues. Had posted a bit in another thread started by Austonwerner4 which can be found here: 458 Even Gears are Gone | FerrariChat

However since my situation is still developing, I'm making this a separate discussion.

It all started at a normal HPDE day, my first with this car at a track I have over 1000+ laps at in Corvettes. I left the 458 in race mode and auto for the first session, intending to just get a feel for the dynamics of the car before switching CT off for session two and aiming to run ESC off by end of the day. But I never got out of the first session.
It was 45 degrees and dry out. It took a full 3 laps per the VDA display for tires to warm up. I maintained 6/10ths driving for these laps. Once VDA went green, I increased to between 8/10ths and 9/10ths. After a few laps, the DCT light illuminated and the shifting was erratic. I drove it back to the paddock.
Ultimately I was able to drive home on 2-4-6-R. The car would go to 1st at a complete stop but seemed very pissed off trying to roll out, bucking in protest until 2 was selected by the computer. Driving home was otherwise not an issue, although shifts between the even gears were very slow.

After getting home, I ordered a Launch X431 PROS V+ Elite and then pulled 9 error codes from the gearbox.


Thinking it is impossible that all the sensors failed at once, I investigated the battery and found the world's cheapest battery installed. It's called "The Usable" which after some research seems to be basically a reject from east penn manufacturing (aka Deka). It also had a C&C battery sticker on it, which is a vendor located in proximity to Atlanta Autos - the dealer I purchased the car from in January. GRRRRRR!!!

So I replaced it with a new Optima AGM yellow top, even though the car had been cranking and starting fine with the junk battery. (I also wonder if this junk battery was the cause of my NVO board failure?) see this thread: 458 - NVO board replacement; dealer alternative | FerrariChat

After following the procedures outlined in the manual, the new battery seemed to make an impact on the situation (for the better). I cleared the codes again but 3 remained (P0931, P0502, and P0793). I ended up taking a 10 mile test drive to a friend's house who also owns a 458 and has experience working on such cars. He was kind enough to be on standby with truck and trailer for recovery if needed. Although the DCT light remained illuminated, and 3 codes apparently wouldn't clear, the car actually drove *almost* normal.
Car is still a bit confused at low speed rolling out in 1st or reverse. Occasionally throws “operation not admissible” upon which it acts like it’s in neutral but doesn’t reflect “N” on the display. That seems to clear itself after a few seconds and then the car applies power again.
The 10 mile drive otherwise seemed totally fine with the gearbox shifting through all gears. 2-7 gears and shift patterns responded as expected in various manettino modes and various levels of throttle and braking. It's just still wonky in 1st and R.
So overall I believe the bad battery wrecked havoc and am still hopeful that either a reset done with a proper computer (not just my Launch X431) or some amount of driving will allow the gearbox to relearn or something. Possibly still have some other electrical or sensor issue though. Encouraged by mostly better behavior with the new battery.
Note P2747 has returned as a 4th code and I can't seem to clear the 4 codes, even though the gearbox is selecting all gears and driving mostly normal. Note these codes are present even when clearing with ignition on / engine off, and trying to clear with engine on, parked. I have not tried clearing while in motion, not sure if that's advisable.

Appreciate any insight the forum may offer. Some specific questions:
1) Will the DCT light eventually go out, similar to a check engine light, after a certain number of key cycles or certain amount of driving if no further issues are present?
2) Is the Launch X431 not able to fully clear DCT codes?
3) Are there any external wires, or grounds that should be checked which might affect the DCT operation?
4) Does the workshop manual actually have a DTC table and symptoms/troubleshooting guide? I couldn't find the DTCs in my pdf search of the manual

 

Found some DCT info online:
MC-10118593-9999.pdf (nhtsa.gov)
Given all 3 gearbox codes are output speed too low, which is caused by electrical fault of the speed sensor, i'm going to start chasing external wiring in the rear.. both even and odd shaft sensors as well as the output speed sensor all have the same type of "speed too low" fault. So I'm guessing there is a harness short or open ground, hopefully external and not internal within the DCT itself.

 

And this manual has photos of gearbox internals and specifically the CCP harness with zip tie inside that I've read about becoming brittle, breaking and leading to wire chaffing.

MC-10171110-0001.pdf (nhtsa.gov)

 

My car is a 2013 FYI. And it got a fully rebuilt gearbox done by Maranello in 2021. So I presume the high temp zip ties were installed.

I’m gonna hook up CTEK charger that just arrived and fully top off the new battery and see what happens next.

 

Apologies to anyone who has been following this thread, that there’s been no update until now, but truth is it has taken me two months to find the time to continue working the problem.
This evening I got back to it. The CTEK obviously by now has fully topped off my new yellow top Optima.
After making no progress with trying to clear the faults I decided to risk another test drive. All 7 gears were available but the car inconsistently shifted well or behaved badly.
So I decided all I can still do on my own at this point is chase down my harness or bad grounds theory. If no luck with that then a more equipped shop would be the best option. Notably I discovered my Launch X-431 will not do the gearbox relearn on Ferrari either.
So anyway I removed the rear diffuser and looked for any signs of obvious wiring issues but found none. I lightly tugged on the two main multi-pin plugs on the left rear of the gearbox and discovered the upper connector outer ring was a quarter turn counterclockwise from its normal secure/locked position. I twisted it and felt a weak detent click. Not very assuring for a lock. Then I pulled the connector out and inspected its female pins. All looked fine so I pushed it back into the gearbox and twisted it to “locked” again.
I turned on the ignition and voila! The gearbox fault light went out all on its own!
I cleared the history DTCs and went for two 20 minute test drives (wife and nephew both wanted turns lol). No faults reappeared and all is normal again.
So glad the issue was external to the gearbox and that I found it before taking it to a shop who might have very well pulled the gearbox out without realizing it had a loose connector!
Now I will safety tie the connector to prevent it from backing off again.
The shifts still seem firmer than I’d expect but being that the box was replaced before I bought the car maybe a gearbox relearn would still benefit the overall behavior.
If anyone knows of a specific drive cycle or procedure I can follow to help the gearbox handoff between gears smoother please let me know. It’s mostly the up shift that seems harsh and especially the 1-2 shift. Feels like my sequential dog ring gearbox in my indy lights car. Smack you in the back of the head type of firm!

 

The prior owner had it done but I saw the invoice and it was $28,400. That included removal, shipment to Italy, full factory rebuild, and then return and install.

 

Correct. The battery and a diagnostic computer were my only expenses. There was nothing wrong with the gearbox except the loose connector.

 

I should also update this to let everyone know that shifting behavior is completely normal now after some driving, it seems to have relearned and a new set of tires solved the wheel hop issue that I was having. I can do launch mode now and the shifts are firm, but smooth, exactly as I would expect it to behave.

 

Post the error codes and I’ll take a look. Battery volts at 12.2 are already a problem, doesn’t have to be down in 11’s. Healthy battery will be 12.5 or more with engine off. Ask your tech what voltage the diagnostic computer is seeing with key on, engine off.

6 codes if all gearbox related could very well be a wiring or connector issue like mine was. Don’t know if it’s internal or external but definitely you want to eliminate the external before pulling the gearbox.

My recommendation is replace battery first if it’s in low 12’s. Then clear codes. Then if you have to remove the subframe to check external connectors to the gearbox it’s still a good step before pulling the gearbox which I imagine also requires removing the subframe anyway. You don’t have to reinstall the subframe to confirm if the situation is resolved (if you find and correct any external wiring). The red gearbox light will go out with a key on cycle if it is fixed.

Good luck!

 

Ah sorry to hear.. but at least you can move forward now.