Volvo Penta TAMD74 P-B


Divergirl

Divergirl

Member
Hi all....I know you have heard me rant about this for years now...it apparently just will not "go away". Those of us with these engines remember the safety recall which involved a wiring harness replacement. VP had this harness done & redone on the SB engine of my boat....never resolved the issue of the SB engine thrusting itself into gear in idle and neutral...yes, I said neutral. They replaced the EDC pad...the potentiometer TWICE...nothing stopped this from happening. Their final attempt was summer of 2017 when they bit the bullet and replaced the SB computer. All seemed to be fine until TODAY when I boarded and started the engines just to warm them up. I was on my dinghy dock replacing the cover on the dinghy...which is in the water right off the bow of the boat....and wouldn't you just know....SB threw itself into gear and Divergirl tried her best to tear herself off the dock...SCARY...I saw a big boat trying to come at me with full force!

I just cannot believe that not one diesel mechanic can figure this out...Volvo Penta can't figure it out....two of their VP partner shops can't figure it out...and I find it also hard to believe I am the only person who still is experiencing this issue! Jlazzfp, on the forum and who owns the same boat as I....same engines....has the wiring harness and no issues like this. I don't know where to turn except to become a non boat owner.

Any suggestions that someone has not made before?

"tanks",
Divergirl:confused:
 
Wow Divergirl!! Can’t believe that happened again. That’s insane. I was told that the issue with the wiring harness was only with boats that had single handle controls. My wiring harnesses never needed to be changed bc I have separate throttles and shifters. My guess is that you have the combo shifter/throttles. Let me know. I will look more into it.
 
jlazzfp said:
I was told that the issue with the wiring harness was only with boats that had single handle controls.
.
Click to expand...

I have two throttles...that is it....one for each engine.
Click to expand...

Sounds like Jlazzfp may have your answer, its in the control handle. Change to 4 handles (2 throttles, 2 shifter's) or fix/replace your current contols
 
Whatever is telling the engine to move is the culprit....and you guys are thinking it is in the throttle for the SB engine, right?
 
Opinion

Your boat shifts and throttles by wire, so moving the lever sends signals to receiving unit. Since there is no issue with speed increase/decrease then I'm seeing the issue only with transmission shifting. The transmission shifting is accomplished when signal from the control lever (throttle handle) open/close of switch contacts. Those contacts may be the issue causing the trouble. Something is sending a signal to the engine control and could be corrosion, worn or weak contacts internal to switches
 
Makes sense....thanks. Keep in mind that I have owned this boat for 15 years and this reared its ugly head early on in my ownership. The BIG problem is finding someone to fix it. I cannot tell you how many diesel mechanics have been at my dock...a lot sent by Volvo Penta in an attempt to resolve this as part of the original safety recall.
 
Divergirl . I think alldodge is on the right path. Everything else was replaced from the wiring harness to the potentiometer and the computer and the EDC. The only thing left is the actual control levers. It would be amazing if it worked and all the money spent by Volvo to try to resolve this issue is directly in the levers. Probably the cheapest and easiest part to replace.
 
It all points to the throttles but who or what kind of mechanic can fix this kind of stuff? My regular boat guy is good about telling me when things are not in his box of talents and this is not. I have reached out to the guy named Carlos...in fact his nickname is "Carlos Controls". He came to my boat last July and fixed the wet corroded solenoid problem. He is busy and lives in MIA, about an hour south of me. He is in demand and is sent out of the country to work a lot. I texted him last week and he has yet to reply. You would think because I live in the year round boating capital of the US there would these kinds of mechanics growing on trees and yet, not one sent to my boat by Volvo Penta, could resolve this issue or even suggest it might be the throttles.
 
Don't have a good answer for you, wish I did.

Maybe try this to see if something shows up. Start the motor, then just barely move the handle FWD then REV just a bit at a time. What I'm trying to find out is if a very slight movement causes it to go in gear. Move it real slow FWD no more then half way and then back to neutral. Then try REV, or even FWD back to neutral then back FWD. Try to find if there is something that makes it start
 
So, AllDodge seems to have hit the nail on the head, again.
I would think that the "fly by wire" throttles in the newer boats used a type of potentiometer, for shifting and throttle response. Corrosion or or something getting in there possibly??
 
This is all starting to make sense to me now. For some reason I thought all of the 41 PCs....perhaps my year and newer...all had electronic controls. I had no idea that was an upgrade from mechanical throttles. So, as I am the 2nd owner and she was only a baby, 1 yr., I knew that the original owners upgraded to diesels however, it never occurred to me until Jlazzfp told us he had 4 throttles...so of course as his controls are mechanical he never had this issue....thank GOD! I reached out to Bryan Boehmer at Formula to see if they could provide any kind of schematics for the wiring, etc. for the two throttles. Unless someone on this forum knows of any. And yes....has to be some kind of corrosion. I am still incredulous that not one mechanic or Volvo Penta, thought about this. As VP did change out the potentiometer and the EDC control pad, I am going to assume that if in fact we are correct, there is corrosion of some sort somewhere else from the actual throttles down through the wiring.
 
I am still incredulous that not one mechanic or Volvo Penta, thought about this.
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I would say most mechanics (self included) would hear something about trouble and wouldn't think that a fairly new boat would not have original factory controls installed, unless pointed out. That said, finding an intermittent issue and/or corrosion problem is tough
 
Thanks kind of wish I did to right now, its cold up here. Then again, while I will work for beer, I can get to be annoying given enough time
 
Ok, you made me really LOL!!! Meanwhile nothing from Formula Tech....they are really slow to reply these days, if they reply at all.
 
Divergirl,

Did you ever resolve the problem with the boat not engaging in gear? I would be interested in learning what the cause was and how they resolved it.
 
So the boat went in yesterday. Started great and ran great at the service dock. Let the engines warm up. Went in and out of gears perfectly. Disconnected lines from the dock, backed away and the port engine stopped responding. No shifting or throttle response. Engine did not stall. Restarted the engine and worked again. 2 minutes later same thing. EDC flashed 3.1 which is potentiometer error. Anyone ever have this issue before ? Can this be the problem with all these engines with difficulty shifting, variable rpms? I hate these electrical bugs as the engines themselves are running great!
 
jlazzfp,
that's a common problem on EDC volvo pentas, you have to make sure that an upgrade kit was installed, you can go to the volvo webb site and enter your engine # and it will let you know if the upgrade was done. The part # you want is
" VOLVO PENTA service kit 74/75 -SPM
VPN 3887834
 
Thanks overboard! I wonder if this was the upgrade Divergirl did last season! I’ll check on it. Great to know. I was going to replace the potentiometer tomorrow.
 
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