Drive Trim Troubleshooting - Where to start?


FTL_Alan

FTL_Alan

New member
2008 350, 496 HOs with Bravo 3s.. port drive trim suddenly stopped working. The boat is on my lift and drives stay in down position. Trim switches are on my port throttle, 3 switches: 1) port up/down, 2) combined port & starboard up/down, 3) starboard up/down. The combined and the starboard will lower/raise the starboard. I hear something when I hit the port trim switch, but no motor or pump sound, more like an electrical connection sound. Visual inspection of the port shows the oil level at about 1/3 of the reservoir, the starboard is about 1/2, maybe a little more. What should the level be, and what type oil? I read some other post that said to just use 10W-40. If not oil level, what would be the next step?
 
First step is to see if its in the pump itself or the electrical.

On the drive pump are two relays, one has a green wire and the other a blue wire. For testing, use the trailer button as this removes the trim limit switch from the equation. Have someone hit the port trailer switch to raise the drive. If if works, you have a limit switch problem. If nothing happens, check for 12V on the blue wire when someone is holding that button. If you get 12V there the problem is at the pump.

Good chance its the trim relays, you can see the two big terminals on top. You can use a wrench or screw driver to short the relay(solenoid) and if the motor spins you know its either the relay or the signal to the relay. I'd be 75% chance the raise relay is bad. If you get it to raise by jumping it, then see if the trim switch will lower it. As always make sure the engine room is well ventilated because you will make a spark if you jump the relay.
 
It was the fluid level.. but it took more than 10 hits to the switch to get the air bubbles out.. I was about to conclude it was an electrical problem, but on the 10th or 11th hit on the switch, I finally heard the pump come on. I guess I created the air bubble when I kept pushing the switch hoping it would come back to life. Lesson learned. Thanks AllDodge and TurboJoe, much appreciated.
 
Think you still have a problem, because an air bubble will not keep the pump from coming on. My guess with pushing 10 or 11 times, you have a switch that needs to be replaced. Replaced my trim switch about 2 years ago
 
One more thing on this thread.. I had filled the resovior before reading AllDodge's comment to only fill to the half way mark.. I filled to the 3/4 mark.. is that OK, or should I extract down to 1/2?
 
I say half way but its up to where the 2 halves of the tank are glued together, so more then 1/2. There will be no issue.
 
Something else still doesn't sound right. Do you have a separate trailer switch? If trailer always works, and trim doesn't then it *must* be something electrical. If you didn't hear the pump at all, then again it *must* be something electrical.
Even with an air pocket, the pump will make lots of noise. It will sound like cavitation but it will always come on. So given an intermittent issue, All dodge is on the right path. But... since you have the combined, and separate switches, and both didn't work that rules out a switch issue. Again, check the trailer switch to rule out a limit switch issue, then change the solenoid/relay on the drive because 99% change that is where the problem is. Make sure you turn battery off before working on it.
 
My bet is it's the solenoid for $12.00 a piece, replace them all, cheap insurance, or keep a spare on board. Only 10 minutes to change it out.
 
2008 350. My problem with trim switches is back, and I was wrong earlier thinking it was related to low oil level. Its the same issue when I posted this thread back in August 2018.. back then the port trim works intermittently, now it only works going down, will not work going up. On my boat, I don't have a separate trailer switch. The trim switches are on my port throttle.. there are 3 switches: 1) the left side switch is for port up/down only (no starboard), 2) in the middle is a single switch that activates both port & starboard up/down together , 3) the right side is for starboard up/down (no port). When I press the port switch up, I only hear a single electrical click (not a repeating click, just a single click, even if I hold the switch button, I only hear the single click). When I press the port switch down, it also did the single click for about 10 presses, then it finally activated the pump and seems to be working again for trimming down. The single switch on the right for starboard is working normally. The middle switch for combined will raise only the starboard (not the port), and it will lower the starboard normally, and it did lower the port before the single port up switch stopped working at all. From reading above, sounds like I should try replacing the port side "up" solenoid first. If that works, then replace the down solenoid, and for peace of mind, go ahead and replace both up and down on starboard trim.

I found this solenoid on Amazon.. is it the right one for my boat?
http://www.amazon.com/Solenoid-Mercruiser-Terminal-89-846070-89-96158T/dp/B00D5V961K

I also found this procedure in a related post, see photo. Just want to confirm it's the right procedure for my problem..

solenoid test.jpg

View attachment 9214

Comparing the instructions to the unit on my boat, I've circled the connections on the port trim where I need to use either a jump wire or try using screwdrivers .. am I on track? btw, on my boat, the port trim is very hard to get to because its at the very back of the port side, across from the back of the port engine, not sure I can get to it.

up.jpg


 
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The trim pumps on a 350 are in a tough-to-reach position, so far back they are almost at the transom.. very difficult to remove solenoids without removing the entire pump. I've disconnected all the wires and the screws securing the bracket to the boat. My question now is about disconnecting the two fluid lines to allow removing the pump assembly. I assume some oil will spill out immediately upon separating the line from the pump. Also not certain which nuts need to be loosened in order to remove the lines in the correct manner. Also concerned about introducing an air lock into the lines which would need more skill that I have to bleed out the air bubble. Any advice?
 
I have changed out full transom assemblies and lines with out having to do a full bleeding as outlined by mercruiser, though I was prepared to. As long as the trim rams are on the drive still the lines shouldn't leak all that much.

The reservoir won't pour out because there are electric valves between them and the lines. You may want to invest in some line wrenches to avoid stripping the flare nuts. If you follow up the metal line, the first nut you come to is the flare nut that needs to be loosened. Hold the bigger nut that this is screwed into from turning if you have to. Be carefull with flare nuts, they take a lot of force to break loose, but then have no friction so its a very common knuckle buster.
 
Thanks TurboJoe for the guidance.. good news, after jostleing the lines a bit (freeing them from the aluminum hook that secures them to the bilge under the engine), I was able to lift the pump with the lines still attached and was able to finally get the bottom solenoid off. The two small 11/32 width screws on the very bottom of the solenoid were the troublemakers. Could not remove them w/o lifting up (and out) the entire pump assembly. I am expecting the new solenoids from Amazon tomorrow. I was careful to take photos of all the connections, but Im worried I may get it wrong. But at least I have the starboard side still intact to guide me. Should be the very same connections.
 
Well.. bad news. After installing the two new solenoids for the port trim, I have lost power at helm for starboard ignition. I think it may be due to the spark that I caused when I tried to bypass the port trim "up" solenoid by using two screw drivers to make the trim motor engage. That caused a bigger than expected spark and I heard some electrical switch noises immediately after. Maybe my mistake was having both battery switches on when I tried the bypass? After the big spark, I did not attempt that again. I did go back to the helm and try the trim switches and both operated as before (port up just made a click, port down engaged, both up and down on starboard engaged). I then decided to disconnect the house, port and starboard batteries before starting the work to remove the solenoids. I turned off both battery switches, disconnected those 3 batteries and then completed the work to replace both solenoids on the port trim. After completing the install and connecting the batteries, I then turned on both battery switches..all normal. I then went to the helm and turned on the port ignition. It made the normal beep but I noticed that VesselView screen did not turn on. I then turned the starboard key on and noticed I did not hear the beep. I then tried the trim switches at the helm and got nothing from any of the 3 switches (port, combined, starboard). All other electrical seems to be working (cabin, cockpit A/C and D/C), except I have no power for starboard. The port engine will start. I can't find any tripped breakers. Could I have damaged the starboard engine computer? Time to call the pros.
 
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Had a spark
I did go back to the helm and try the trim switches and both operated as before (port up just made a click, port down engaged, both up and down on starboard engaged)
Click to expand...

So everything was working as before the spark, then bats are disconnected. When bats are turned back ON there is an issue.

Now if things did not all work after the spark I would look at the 90amp fuse on the starter post

90 amp fuse.jpg
 
Yes, immediatley after the spark, I went to the helm and tried the trim switches and they worked the same as before the spark. I did not try anything else at the helm, only tried the trim switches. Then I turned off the battery switches and disconnected those 3 batteries and started removing the solenoids. Finished the install, turned the battery switches back on, went to the helm and turned on the port ignition, all normal..then tried starboard ignition and noticed absence of the normal beep. Then noticed no response from any of the 3 trim switches. Are you recommending I check the starboard starter fuse? I forgot to mention that I did check the fuses on the port trim after the spark, both were intact.
 
tried starboard ignition and noticed absence of the normal beep

Are you recommending I check the starboard starter fuse?
Click to expand...

Yes, start there and see if you have power thru the fuse.

If power is good, check for power at the Red/Purple at the Key switch.

If good, check fuses on the motor should be 3 of them under a cap.

In most cases there is a master and slave motor setup but need to find out if power is making it to starboard before going further
 
Finally figured out my issue. See the yellow-circle in the photo. This bridge connection has a one-way diode. When I reassembled, I failed to attach it correctly, so the diode was not functioning. This one tiny piece on the port trim caused the problems I mentioned in the post above. As soon as I reversed this one piece, everything works normal again, and I now have a working port trim, up and down. Another mistake I made (but not a cause for my issue) is failing to turn off the battery switches before trying to jump the solenoid. Before doing something like this, need to have the battery switches off.

Capture.JPG
 
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