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Transmission Issues in 2021

10331 Views 66 Replies 15 Participants Last post by  gkardr6
Title: Transmission Issues in 2021

Hey all,

I've been experiencing transmission issues similar to those that others have had in the past, and am hoping for some help to understand how to diagnose and fix these problems. I've had the same issue three times in a month now:
  1. I drive the car for a while with no issues (the first time I had been driving the car for about 3 hours, the second time I had only driven it for about 30 minutes)
  2. Park the car and turn it off for a little bit (the first time this was only a few minutes as I filled up for gas. The second time the car was off for ~2 hours)
  3. When I go to restart the car I get the "Christmas Tree of death", reverse and manual mode are not available, and only 2nd, 4th, and 6th gears work. The first time this happened the car actually got stuck in reverse for a bit before it finally went into neutral, but then couldn't go back to reverse or into 1st/3rd/5th.
  4. No amount of key on/key off/reboots changes anything. If I pull the negative battery terminal AND let the car sit about 30 minutes, it will suddenly fire up just fine. All the warning lights go off except the CEL, all gears and modes are available, and the car shifts just fine. After driving for some amount of time, the CEL also clears itself.
  5. The third incident occurred while driving this morning. On the freeway with the cruise control engaged and car in auto mode, the transmission light briefly flashes, CEL illuminates, I get a bunch of warnings, but the car continues to shift fine in auto mode. Once I parked and turned it off, it now has all the same problems as in #3 when I try to restart it.
After the first occurrence, I took the car to the dealer and they could find nothing wrong. They double-checked the software was up-to-date (I even provided the number of the SW patch below) and confirmed there was nothing available. They then quoted me $9,000 to replace the transmission, so I took the car back and decided I would have to solve this myself.

To start, I've read all of these threads:

Transmission Failure
Transmission Failure Poll
Heads Up On a TRny Issue
Inconsistent Problems: “The Christmas Tree of Death”.

The problem is that the majority of the problems people had occurred early on, and dealers either solved the problem with a software patch which predates the build date of my car (I have a 2016) or they replaced the transmission. My car is out of warranty so a trans replacement "just in case" is not in the cards.

From what I can gather, these are the possible sources of the problem. Is this list complete and in which order should I troubleshoot this?
  • Clean/brush battery terminals and add dielectric grease - already tried this after the first incident, didn't solve the problem
  • New battery - I tested the battery at Autozone, they claim that it's totally fine, not even marginal on startup
  • Get the software patch that worked for others (CFC8TDW.01-00-UF14M080) - I gave this number to the dealer and they claimed everything is up to date
  • Check/refill "Robot mechanism" (shift actuator?) fluid level
  • Replace shift actuator pressure sensors with this part: Pressure sensor - Alfa Romeo TCT - SequParts
  • Replace voltage regulator for shift actuator
  • Replace hydraulic actuator p/n #68303710AA
  • Replace transmission
Also, is anyone aware of an Alfa tech or indie shop somewhere in the US who actually has experience troubleshooting and solving these issues? The tech at the local dealer had seen this problem many times on Fiat 500Ls, but said that they just R&R the transmission every time, so he didn't have any idea how to diagnose the root cause.

Any help would be appreciated, I don't feel like I can trust my new car enough to drive it anywhere until this gets sorted out.
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One big issue in attempting to fix the trans is that the DCT trans have low 'fix rates' as a product across all manufacturers. Going one level deeper on FCA products (Fiat-Chrysler) is that they tried to resolve many mechanical issues by fixing the original version (same architecture) found in other FCA products... to repeated failure and triggering the Lemon Law... which saw them ordered, by court/judge, to cease repairs and only replace them with updated units.

This was good news for those affected and chasing their tails under warranty, as repair after repair failed. There is bad news with that: Now there is no established knowledgebase or supply chain to allow repairs. The seeds of repair are barely at sprout level. For a trans used so widely, the reparability should be high. It exists, but it is primitive and limited. An actuator here or there, and lots of 'let's try this' ... which is thousands of dollars which might never avoid the cost of getting a replacement, but is just money piled on top.

They proved they are incapable of fixing them; they triggered the lemon law as a result; the courts ordered them to cease repairs, and now you are left holding the bag, because you seek repairs. Can't blame the courts, as FCA proved incapable, and there does not seem to be real hope beyond a crapshoot anywhere else.
Yeah, that's unfortunate. The car shifts fine when it's not glitching though, so I think this is a fixable issue that does not require trans replacement.

Have you asked for a transmission recalibration? Something about adjusting the kiss points of the clutches. My tech gave one to mine last year, I thought as a preventative measure, because I really couldn’t detect anything wrong with it. It did smooth out the changes in certain circumstances. These things are too clever for their own good, and ours.
I didn't ask, but when I brought it into the dealer, they suggested that they may reset the contact points once they had looked at it. It's not clear if they actually did this though.

How many miles do you have on your 4C, and have you ever tracked it? I'm at 12K on my 2016 so far zero issues but planning to have bolt tightening and other service performed soon in Atlanta. Will definitely be asking about the DCT.
I have 18K miles on mine. Never been to a track day as far as I know, although I did run an autocross with it back in February.
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Almost forgot that I took screenshots of the OBD codes I could read with my cheap Bluetooth OBD adapter. This is from the first time I had the issue (although it is after I pulled the neg battery cable):

And this is after this weekend's issue (again, post-reset):

It was suggested to me offline that I buy the Foxwell code reader to grab and reset anything that maybe isn't showing up with my cheap adapter. I have one on order (they are on sale on the Foxwell site right now, btw) and will post any additional codes that I can see once I have it. A quick Google on the codes above shows some possible issues related to the gear position sensor, so I may add that to the list of possible trouble areas.
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All things considered.... reading all the information again... a mechanical issue should not come/go... and you're a 2016, but with right software in the TCM.

Has anyone considered replacing the Trans Control Module (TCM)? 2015-2016 TCMs could be compromised by water.
Yes, I should add the TCM as a potential culprit. I will definitely pull off the shield and connectors and inspect the connections for water intrusion, but I'm guessing it's not the issue here (see below).

So i had the Christmas tree lights happen once in the past. So many lights i could not keep up with them all... Freaked me out. I believe it was voltage related. Put it on the tender and never seen this again. Been a year or so. Just had my battery changed also last week. In for service but felt since it was a 2016 even thou they told me battery was fine these cars are finicky when it come to voltages.
I put the car on a Battery Tender after the first occurrence just in case, but it didn't prevent the last two happenings. I'm still keeping the battery on the list of problem areas though. The AZ heat is known to kill batteries and if this is the factory battery, it's end-of-life anyway.

My car is also MY2016

I'm pretty sure the problem some have is because of the routing of the wire to the TCU. 100% sure water gets into the back of the connector and migrates into the connector on mine.

I plan on flipping my TCU over so the connectors are facing down.

Most of the body computers and wire harnesses I've been offered also appear to show issues with water running down the wire harness corroding connections, obviously creating a range of electrical issues.
I could definitely see this being an issue, as I actually lived through this problem (water intrusion via wire harnesses) with an automotive component I designed at my job several years ago. However, I would be surprised if it's the problem here - I live in AZ where it's very dry all the time, and when I wash the car I use Optimum No-Rinse, which means that I don't even hose the car down. So if any water is getting in the engine bay, it's a few drops at best. The car did come from Florida and Virginia though, so it's not impossible there was existing corrosion before I bought it.
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OK, a couple of updates - some good, some bad:
  1. I decided to check the battery myself and found that it was dropping to ~10.5V when cranking, so I decided to replace it with a new Duralast AGM. Unfortunately this didn't fix anything, but at least I can cross the battery off my list. I also checked the charging voltage (rock solid 14.2V between idle and 2500 RPM) and confirmed the hydraulic actuator fluid level is full, so those are also off the list.
  2. I bought the Foxwell code reader and it has been very helpful. So far I have seen multiple instances of the same code, P1C9900 "Gear position sensor 1st/3rd - signal frequency incorrect", which occurs when the transmission light flashes, either at startup or while driving.
  3. I drove the car a bit this weekend and the fault is now becoming persistent (i.e. no longer momentary), which means that the car goes into limp mode and won't come out, making it nearly undriveable. The only consistent pattern I'm seeing is that the fault only seems to occur when the car is fully warmed up, or on startup after a drive of 20+ minutes. However, I've also seen it go away after driving the car for a while (I had to limp the car home on only 2nd/4th/6th gears for about 60 miles on Saturday), so I'm not sure what to make of all this.
Given that this is the only code in the TCU when this is happening, and it's now happening with more frequency, I'm thinking I need to narrow down my search to either this 1st/3rd position sensor, the shifter selector position sensor, or the wiring harness around it. As best I can tell from reading the TCT training manual, this 1st/3rd position sensor is part of the "integrated sensor module" located on the backside of the hydraulic actuator (page 39 here). So this leads to a couple of questions:
  • Has anyone pulled off the hydraulic actuator themselves yet? I don't see a procedure for it in the eLearn manual, but I saw other threads where dealerships replaced it under warranty, so I'm assuming it can be done (and hopefully with the powertrain still in the car). Not sure if I need to plan for draining and refilling the hydraulic fluid, or if the system is self-contained.
  • Does anyone have access to a parts manual that lists this sensor module with a part number? I haven't been able to find anything online. Really hoping I don't have to replace the entire actuator (~$2100) just to get a replacement sensor module.
I just got all the parts to change the timing belt, so my plan is to start pulling it apart to do that service, and while I'm in there I will replace either the sensor module or the entire actuator, and also inspect the wiring. Hoping I can get some help on part numbers so I can get something ordered, otherwise I'm about to become the parts guy at Scottsdale AR's best friend, lol.

P.S. Another idea is to buy this hydraulic actuator from a Dodge Dart and just swap over the sensor module. Would be way cheaper than a new actuator, but seems risky until I can confirm the sensor modules are the same P/N. Any thoughts on that?
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@nate37 have you considered just replacing the TCU itself? Wondering if everything is actually fine, but there's just weird computer gremlins? The reason that I ask is, my understanding was that they won't sell the actuator or parts of the trans, and will only replace the full unit?
Well I'm trying to avoid just throwing (expensive) parts at the car, but to your point, a TCU is definitely cheaper than an actuator. You're also right that at this point I have no way of knowing whether the issue causing the fault is at the sensor or the TCU. Maybe if someone has a spare TCU laying around that they would let me borrow I could test that theory? :geek:

BTW, it is possible to buy the actuator separately: Clutch Hydraulic Unit Motor Mopar 68303710AA fits 16-18 Alfa Romeo 4C for sale online | eBay

I would take up Alfa Romeo Care up on their offer for help. In the background, with the details you have, they will reach out to their network to see if anyone solved a similar problem. I am a huge critic of service I receiver everywhere, but they are great and responsive.

Don't know what to say about the actuator gambit, other than Amazon has a good return policy. Maybe use it as nothing more than a test item to clear a variable? -- but I don't know about compatibility.
Yes, I agree. Been meaning to hit up @AlfaRomeoCares to see if they have any additional knowledge or could at least help me find a replacement sensor module, but haven't had a chance yet.

Were you able to rule out the wiring harness connections to the TCU (corrosion issue)?
I know that you said it wasn't likely from your ownership, but the car's past life and the heat where you live might have caused latent corrosion, just enough to cause this intermittent gremlin.

I would think this a worthwhile check before starting to disassemble parts of the transmission.
I haven't yet. My DIY timing belt change has been a disaster (see my other thread), so I'm still trying to get that sorted before I come back to this issue. Once I finish the belt (almost done) I plan to take off the driver side quarter panel so I can inspect the TCU connections, chassis ground connections, and as much of the actuator wiring harness as I can get to. Definitely doing this before I start taking the transmission apart. From what I can see, removing the actuator might be a pain. Not a lot of room to maneuver it out.

Good information.

To trigger these re-learns, they connected their system, or just disconnected the battery?

I assume the former (I think that the only transmission re-learn you can do without the diagnostic equipment is the "fine clutch adjustment", but would be happy to be corrected).
I know that my Foxwell reader has the all the transmission re-learns included in it, and it looks like there are several re-learn procedures for the ECU also. Seems like the easiest way to do it.
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Just following up here and hopefully turning the page on this issue. I took my car up to Las Vegas to have Towbin Alfa Romeo service it, since they had recently fixed a similar problem on another forum member's car. After a lot of diagnosis (they could never reproduce the faults, go figure), we eventually decided to replace the transmission hydraulic actuator. This was based on the fault codes I had saved, the fact that replacing the actuator fixed the other car that was throwing a similar code, and also based on some back-to-back drives the dealer did with another 4C, where they noted the shift quality was worse in my car.

Happy to report that I picked the car up from the dealer and drove it back to Phoenix yesterday (~300 miles) without issue. The dealer put another ~50 miles on it to verify the repair, so I'm over 350 miles now, where previously I was seeing the fault every 5-100 miles of driving. The car also shifts MUCH better than before, with a lot less clunkiness in both manual and auto modes. I didn't realize how bad it was before, since it had been that way for the entire time I've owned it (since last Jan). So I'm very hopeful the bad actuator was the issue and I can start to enjoy this car again! I'll post back here if this same issue crops up again, but just wanted to get this info out here in case anyone else runs into a similar problem in the future.

Also, major shout out to Towbin AR, who were awesome to deal with. They had excellent communication throughout the whole process and did absolutely everything they could to diagnose the root cause before just throwing parts at the car. Their pricing was also more than fair given how many hours of diagnosis they had into it. They're by far the best AR dealer service department I've interacted with and are now pretty knowledgeable on this problem, so I would highly recommend them for anyone else on the West Coast who runs into this issue.
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Hi, My 4C has 70.000 Km and I experience the same problems now. I am using the Multiscan 4.7R3 tool and did all Adjustements. In the Production/Service final calibration procedure, all elektrovalves, potentiometers and mechanical components of the whole actuation unit, are tested. So, in your case, it would also test the integrated sensor module. So my suggestion is to run this test and than do the clutch self-calibration enable. In my case I first got the error code related to the electropump of the power unit. I changed the electropump,the accumulator and the elektronic control unit of the elektropump, but without any succes. During a trip in the Italian mountains, I got the same problem. Now I am going to replace the clutch, because with 70K and at least 50% driving in the mountains, I think the best is gon and the clutch is worn.
Sorry to hear you're having the same issues. I suspect we will see more cars have this problem as time goes on. Good idea on the testing - hopefully that helps someone in the future.

In my case, the electropump was fine. The hydraulic actuator was the issue. With a new actuator, the car shifted much more smoothly and no more errors. I have about 2,000 mi (~3200 km) on the new actuator and have had zero problems. Did you get the same trouble codes as I originally got (P1C9900)?

I would suggest looking into the actuator before clutch replacement. Or, at the very least, inspect the clutch and if it's not worn, I would look hard at the actuator. In my case, the dealership was able to pinpoint the problem by driving my car back-to-back with another 4C and the difference in shift quality was immediately noticeable. That plus their previous experience replacing the actuator to resolve the same codes, led them to replace the actuator on mine. I know back-to-back test drives is not always doable, but they got a little lucky.
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When you were having issues was reverse available? My car is currently in the shop and I am trying to help the tech with any guidance as far as known issues.
Ah sorry to hear you're also having issues. When my car would fault I would lose R, 1, 3, and 5. These gears are all on the same shaft, so my guess is that the gear position sensor on this shaft would fault and the TCM would lock out all those gears to preserve the transmission.

You might have your dealer call Towbin AR in Henderson, NV, since they have experience fixing this problem on at least two cars now.
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