Thrust vector module (TVM) maintenance alarm

cbruck

Member
Jul 5, 2016
40
Ocean Springs MS
Boat Info
2010 SR Sundancer 390 I/O's with 496 MAGs and Axius Drive
Engines
496 MAG's
Have a 2010 Sundancer with Gen I Axius. I’ve just started getting a TVM maintenance alarm- non- critical. Does anyone have any experience with this? I can’t seem to find any information anywhere about this alarm or any troubleshooting.
 
Not sure if it's common knowledge, but TVM = Thrust Vectoring Module = the hydraulic actuator used to position the sterndrive in an Axius system. It has its own firmware (separate from the CCM and ECM) and it controlled via the CAN bus by each respective CCM.

I don't know if this helps, but this is the explanation of that fault "TVM_Fault_NonCritical" from the Merc Gen I/II Axius service manual:

Description:
"This is a TVM flag fault reported through the CCM. The CCM, TVM and sterndrive are from the same engine. Other TVM faults will provide the details necessary to resolve the problem."

Actions:
"Do not diagnose this fault. Instead scan the TVM module directly for noncritical faults. TVM faults not specifically labelled critical are noncritical faults. This flag fault will automatically clear once the TVM noncritical faults have been resolved."

I realize there's not a lot of definitive help here, but it does seem to suggest there should be some other TVM fault occurring and this one is simply an indicator of it (and should clear when the underlying fault is remedied).
 
Thanks for the input. I do have an axius manual on the way. I did get a little help from Mercury that indicated a few things to look at such as the sensors or wiring can be resetting the TVM. I can't seem to clear the alarm through vesselview but that may be because it is randomly recurring. It may be time I invest in the diagnostic software.
 
As far as I know, the Merc CDS software is available to (authorized and current) dealers only. I really despise this limitation, but from a business perspective, I understand their position.

If you can somehow find access to the CDS software (along with the required USB-CAN bus interface), it's diagnostics are really the key to solving issues like this. From my experience, the aftermarket diag software doesn't have the proprietary PGM tables in order to properly decode the CAN bus messaging, especially with Merc-specific technologies like Axius.

I'd be interested to know what you find/figure out...
 
I did find this one on Amazon:
https://www.amazon.com/Mercury-Merc...r=8-1&keywords=mercruiser+diagnostic+software

I'm not sure if this has the connectors etc for the interface or not.

That is the correct software (v1.7.1 is the latest version), however, you cannot run it successfully. The initial launch screen will require you to enter your Mercury dealer id number and license activation key.

It does not include the needed CAN bus hardware interface, though you CAN buy that if you look around enough as they appear to OEM a unit from KVaser (kvaser.com).
 
I did get the October 2016 Mercruiser axius service manual, which is excellent by the way, but I didn't find anything about TVM maintenance required fault. What page did you find your information? I did get this from Mercruiser:
upload_2018-6-17_10-50-46.png


I think I'll concentrate on the sensors. If not I may go for the diagnostic software.
 
Your Axius manual appears to be much newer than the one I have. Mine is from December 2011.

I did notice that my manual lists the closest fault as "TVM_Fault_NonCritical" vs your "TVM_Maintenance_Required_Fault", which isn't even in my book. Base on this, I'd probably follow your instinct along with the fault text and try to verify the steering position sensors as those seem likely problematic.

I can also say that the CDS G3 software would tell you exactly what you need to know. It's rather impressive in its capabilities regarding all the engine/drivetrain sensors and calibrations. I just wish, as owners, we were "allowed" to run it.

FWIW, this is the cover of the manual I have:

uc
 
I've been working on the problem and here is some history. The TVM alarm came up about a month ago but only after the boat had been driven about an hour, then it would repeat the alarm every 3-5 min. (very annoying). Then about 2 weeks later I turn on the key and got a different, strange alarm. I saw this before so I checked the batteries and they were low on water and running about 12.1 Volts. So I added water and got the voltage up to 12.6 V. So I ran the boat several times after that and no more "strange" alarms but my TVM alarm is back again after running the boat for period.

I've had some discussions with the dealer and on my boat with the Gen I Axius, they indicated that the TVM's are very susceptible to lower voltage. Obviously 12 V's or lower. They suggested resetting the software may fix the problem. But logically my strange alarms come on just when I turn the key on but this TVM alarm only comes on after running the boat for a 1/2-1 hr. Mercury does recommend using batteries at 1000cca or better in the hope of keeping the voltage high.

Corrupted software may be the issue but it's seems unlikely that it would take an hour of running before the corrupted software would set a false TVM alarm.

The books seem to be well written and have quite a lot of information regarding the diagnostic software as well. I am looking hard at the software but so far I have not been able to confirm that I can run ver. 1.6. Any direct knowledge in this area?

By the way, I'm 100 miles from any qualified technician, is the reason I am working on resolving this issue.
 
Like you, I have always been told that the Axius system is very voltage-sensitive...so much so that I've read that Mercury had a program after Axius was initially released (2008/9) whereby they visited vessels and replaced the batteries w/ high-cca AGM batteries (Optima) in order to address similar erratic system behaviors. FWIW, my boat's original owner, on the advice of his local Merc dealer, installed Group31 Optima's just prior to selling.

Along the lines of determining whether low voltage may be involved with causing the fault, I can think of a couple things to perhaps verify:

1. Confirm the condition of your batteries at the time(s) you see the fault recur. That is, are they at a suitable voltage at that moment?

2. Confirm your alternators are performing as designed so you're not slowly draining your batteries as you run. This scenario would only make sense if they were charged again at your slip via shorepower + charger.

I have no experience with CDS v1.6. It may not have the dealer id/key requirement that the later/current version does. If it doesn't, then theoretically, you could probably get more detail from the TVM/CCM when the faults occur using it. Sadly, the cost of the software + CAN bus adaptor makes it an expensive experiment...
 
Just to follow up on this post. Finally got the boat to Marinemax and the TVM alarms ended up being caused by a wiring harness intermittent.
 
By wire harness intermittent do you mean a loose plug? I have also been getting a Port CCM TVM non critical fault. I did have a tech come out with software and check it out. He also spoke with Merc and they decided to swap shift actuators on engines to see if fault would go to STB. I have got the fault again on PORT but seems to be a lot less frequent. In addition after work was done my auto heading will not engage, it just gives me 5 beeps and goes back to standby. Which sucks as I like the auto heading feature.
 
My TVM fault ended up being a steering sensor that was not reading properly, replaced and so far so good.
 

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