Yanmar Neutral Safety Switch

K

knotflying

Well-known member
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Jul 25, 2010
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Fluid Motion Model
C-28
Hull Identification Number
FMLT2731J011
Non-Fluid Motion Model
25' Parker & 246 Robalo Cayman
Vessel Name
http://illusionsmikeandjess.blogspot.com
I have seen a few of us that have start issues related to the neutral safety switch. Mine was starting to act up and so was Gansett Ranger's and he had replaced his in September. He still had periodic no start situations. We started to suspect that there may be another culprit. We did a little testing on the switches when the symptom was that it would not start in neutral. There was definitely no closed circuit when in neutral. We checked the old switch that Gansett replaced in September and it seemed to work. After close examination we discovered that the bracket that the neutral safety switch attaches to has the ability to be adjusted. We marked the position then loosened the screws slightly and then tapped the bracket just a hair closer to the cam lobe that the switch touches. After tightening the screws we turned the ignition key and she started. So far after several starts we have had ignition consistently. So before assuming your switch is bad check the bracket adjustment.
 
Mike:

Thanks for this information, it never hurts to learn from others. Can you tell us, for those like me that do not know, where the neutral safety switch and bracket are located?

Jim F
 
Had the same problem and employed the same fix. Hasn't been an issue since.
 
trailertrawlerkismet":lu7f63k9 said:
Mike:

Thanks for this information, it never hurts to learn from others. Can you tell us, for those like me that do not know, where the neutral safety switch and bracket are located?

Jim F
Click to expand...

Look at where your shift cable terminates. There is a cam leaver and the neutral Safety switch is on a bracket and rides up against the cam. It has two wires coming out of it.
 
This is an amazing site full of clairvoyant boat owners. Tuesday I got the dreaded neutral safety alarm with no start. So no day on the water. I will try this fix next week when on the boat. But here is the catch. I pulled the two wires that go to the switch and tried to jump them by wiring them together. Nada. That makes me worried I may be dealing with another problem.

These are finicky boats, that's for sure.
 
Hydraulicjump":96s58qu0 said:
This is an amazing site full of clairvoyant boat owners. Tuesday I got the dreaded neutral safety alarm with no start. So no day on the water. I will try this fix next week when on the boat. But here is the catch. I pulled the two wires that go to the switch and tried to jump them by wiring them together. Nada. That makes me worried I may be dealing with another problem.

These are finicky boats, that's for sure.
Click to expand...

Just to make sure, I assume you jumped out the two wires going to the engine after you disconnected it? Your post sounds like you jumped the wires going to the switch. That won't work. It has to be the wires going to the engine.
 
Ha! Just to make sure, I surely do NOT know what I am doing and appreciate the input. Here's what I observe. The neutral safety switch is activated by the lobe on the lever that operates the transmission. When in neutral the fat part of this lever depresses a plunger in the switch which opens a connection, signaling that it is in neutral and allowing the engine to turn over on the start. Two wires come from this switch and head off into a flexible conduit, which I presume goes to the ECU, but I was too lazy to follow it. I unplugged the two insulated bullet connectors and tried to wire the two wires together on the ECU/ignition side. No change in conditions. I also tried repeatedly, when things were still hooked up properly, to find the fabled sweet spot, but had no success.

I have ordered a new switch. It is the cheapest part sold by Yanmar as far as I can tell. But I've put the wiring back together and will try adjusting the depth of the switch when on the boat next week. Since trying to jump the connection didn't work I am skeptical that I will be successful.

Any advice welcome.
 
Hydraulicjump":2628soyy said:
this lever depresses a plunger in the switch which opens a connection, signaling that it is in neutral
Click to expand...

I'll let others chime in here if I'm incorrect, but I assume that the switch, when activated by being in neutral, is actually CLOSED not open. That would be my assumption. In any case, take your multimeter and measure the resistance across the switch when the wires are disconnected. As you activate the switch it should change from no resistance (or close to zero) to infinite resistance or vice versa, That should tell you if the switch is working.
 
I have had this problem , and it is usually after myself or others have been working around the engine. I suspect working in the tight quarters sometime things get bent a bit by accident.
 
Please clarify that this pesky switch is located on the transmission just forward of the shift cable and not in the shift lever mechanism at the helm. Thanks.
 
viewtopic.php?f=5&t=6307&hilit=Yanmar+safety+switch
There is a good pic of it in this older thread. I have the Yanmar part number in the thread also.
In the pic you can see two Phillips head screws, that is what provides the adjustment as previously explained.
 


Enlarge picture.
#1 Is the switch itself
#2 Are the screws to loosen and adjust bracket
#3 Is the Cam bracket that the switch rides on.

If you remove the switch, put an ohm meter or continuity check on the two leads. The switch is normally open. When you press the switch in the ohms should go to zero or the light will go on or buzzer will sound . Then you may only need to adjust the mounting plate. If not it is a bad switch. Try jumping the leads to the engine and it should start. MAKE SURE YOU ARE IN NEUTRAL! If after that the engine won't start you are entering the world of unknown.
 
Thanks guys, now I know where to look and what to do....if....
 
As promised, I returned to the boat this evening after work. I spent 2 hours on this project and, at the outset, let me thank those who offered advice and particularly to Mike for bringing this all up. The end of this story will sound familiar.....

Being classically trained in the sciences, I set this up as a series of hypothesis tests. Here is how it went.

The null hypothesis (that there really was no problem and I just had not tried to start it enough) was rejected when it would not start. Same "neutral safety switch" error code. Batteries were all charged.
The "neutral safety switch is not adjusted correctly" hypothesis was rejected after adjusting the mechanism as per earlier posts on this thread.
The "switch is broken" hypothesis was rejected. Using the multi-meter I could tell that it was working just fine, thanks for the instructions Mike.
The (not discussed in this thread) "reset the ECU" hypothesis was rejected when I took all the ground wires off every battery, cleaned and reinstalled after letting them sit, and it didn't start. Same error notice.
The "it's the corroded grounding buss" hypothesis (which was pretty reasonable since the nuts on the studs were a wee bit loose and corroded) failed when I cleaned everything up until it shined and it didn't start. I have ordered a new buss anyways and will install next week.
The "it's the brand new engine ground wire I put in weekend before last" hypothesis was tested. And to be clear, this was the least likely culprit since there was obviously no corrosion on the cable and when I installed it there was zero corrosion on the engine mount. Also, it worked just fine after installation. BUT, I noticed that there was still paint at the contact on the engine block and wondered if this was the problem, causing a weak ground. This is also where my nephew had stomped around while helping me clean. So I pulled the cable and attacked the connection with wire brush and sand paper until there was plenty of gleaming metal. Yep, you guessed it, it started just fine with no error alarms. Obviously, I rejected the original hypothesis of a broken switch.

Not entirely sure what to take away from this (Mike or Howard will chime in probably), but 1) I have been battling grounding issues for the last three years on this boat. The object lesson is to aggressively maintain grounding contacts. 2) when something goes haywire that might be electrical, go through the ritual of checking grounds first before calling a mechanic who will probably just do the same, 3) don't believe the error codes (I replaced a whole set of glow plugs based on these spurious codes and if you look at earlier posts, that was dumb), and 4) well, I am not sure what four is other than these boats are delicate electrical flowers.....to a fault!

inside pun

Jeff
 
Glad you resolved your problem and it is good to know that the error code is not necessarily the neutral safety switch. A Yanmar tech told me that grounding is highly important on these engines. Many an erroneous code comes up because of poor grounding. The ECU has a positive and negative connections directly from the engine battery to the ECU. These must be clean! I also ran an additional ground directly from the engine battery to the block and cleaned the paint off the block before attaching it. In my opinion there are too many connections between the grounds connecting to the ground block and then to the engine.
 
A few taps with a ball peen hammer did the trick.

Thanks for the great tip.
 
My mechanic working on a Starter issue (now an alternator issue) didn't like seeing the ground connected to the transmission and moved it to one of the starter bolts. He said that should be bullet proof but he wants to add a second ground too. GF
 
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