2003 Yamaha F115TR Main Relay Issue

I have 2003 Yamaha F115TR motor that cranks fine but will not fire. No spark at the plugs, checked one on each ignition coil.

I have isolated the issue down to something related to the main relay. I have removed the relay and bench tested it. Contacts close withe +12Vdc across Yel->Blk or Grn->Blk. Contacts have 0.52ohms across when closed. This could be a bit high, but not sure this is the issue. If I short the Red->Red/Yel wires in the relay connector the motor starts, so I know the issue is getting this relay pulled in properly.

I do not see +12Vdc at either the Yel or Grn terminals of the relay connector with the key in RUN or START. This seems to be the most likely issue. Unfortunately I do not have schematic for the boat (Lund 1700 Fisherman). From what I am guessing, the Yellow wire comes from the keyswitch which has +12Vdc at the keyswitch. The Grn wire looks like it comes from the ECU, but there is also a Grn wire that comes from under the dash.

I feel like I am really close, but struggling with next steps.

Anyone know where the yellow and green wires for the main relay come from? When should they be hot? What is too much resistance on the contact side of that relay?

On a side note, but may be related which is why I bring it up... my trim gauge has been acting up lately where it never shows the motor fully down. I ran the motor all week last week with no issues. Is there a chance this sensor has come out of adjustment even further and that the motor won't fire with the sensor out of adjustment? Would this prevent the main power relay from not activating?

Re: 2003 Yamaha F115TR Main Relay Issue

you need a manual, they are about $5 on e-bay on a CD. but my guess is that the wires go to the ECU, as everything seems to run through it, I would check the kill switch, all wires for a short, and eliminate every other possibility before replacing the very expensive ECU. Did the motor start having some skipping or just not running right issues before?? also did it hesitate more than a couple of seconds to shut off after turning off key switch?? these motors seem to have a real common issue with the ISC valve sticking and causing the ECU to overheat and damage the unit. the ISC valve is a pricey little part too, so I soaked mine in Sea Foam for 2 days and it started working again. lucky me. these motors are plagued with stupid issues and parts are ridiculously over priced, wish I could sell mine, been trying for 6 months, even though it runs great now and even gets good gas milage, I would rather have a carbbed 2 stroke any day.

Re: 2003 Yamaha F115TR Main Relay Issue

Thanks for the ideas. I have the service manual, but they just show the green and yellow wires going to the boat interconnect. Green also goes to the ECU. Boat ran perfectly 4 days in a row. Parked for one day and wouldn't start the next. I did haul it a couple hundred miles between. Once the contact side of the relay was bypassed, the motor started. That gives me hope its not the ECU.

Anyone know what it takes to get the diagnostic codes out of the engine? I have nothing on the blue/wht wire that is supposed to flash codes.

Re: 2003 Yamaha F115TR Main Relay Issue

Is a subject I was going to do an info post on but will mention it here. If I follow you, you say you bypassed the relay and it worked. Yesterday I took my tilt/ trim relay apart to see why it was intermittently inop. Put a new one on. I am mentioning this because there is a good chance YAMAHA gets all their relays from the same vendor.
Although the relay appeared to be a well built, sealed unit, I was very surprised when I opened it up. The actual contacts were nothing more than pressed in dimples or pimples on a thin strip of metal, no real contact points as you might expect. One contact point was pristine while the other 3 were black, burned, really disappointing. Although it is an 05, it only has 220 hrs. on it, how much could I have used the tilt/ trim? This is an intermittent relay not constant duty so it might be built cheaper than a constant duty. Have also considered that my pump motor was drawing more current than the relay was designed for. I also replaced the pump motor. Anyway, do not rule out the relay, if it is anything like the TT relay, the quality is not what you would expect. Am becoming very disenchanted with YAMAHA lately.
Am not trying to sound like a know it all. During my carrier, one of my jobs was maintaining the container loaders that run the big pallets into the plane cargo compartments as well as de-icer trucks. Everything is hydraulic, controlled by 12 volt relays, dozens of them. Was very rare to have a bad relay.
As for your trim indication. The shaft coming out of the position transducer needs constant lubrication, it is hanging up. Use WD-40 or something. While looking at that, the wiper on the shaft could be broken. They are plastic, replacements are metal. regards FRED

Re: 2003 Yamaha F115TR Main Relay Issue

Thanks for the feedback on the relay Fred! I agree and with a pricetag of $111 for what is probably a $15 part I agree that Yamaha is really raking in the margin on these parts. My only hesitations about just replacing the relay, are twofold... 1) no dealers around me stock the part which leads me to think it's not a frequent failure point. 2) I cannot get 12V at the coil side of the relay leading me to believe it's an issue with either the Grn or Yel wires that energize the relay and not the contact side.

The schematic shows both those wires going to both the boat harness and the ECU. Unfortunately I don't have a boat schematic and I cannot trace them back to the keyswitch or other. I am wondering of the ECU is powered from the keyswitch or the main power relay.

Re: 2003 Yamaha F115TR Main Relay Issue

I forget to mention, the trim sensor turned out to be the cam that rotates with the motor was broke. Sensor outputs correct values, so I need to order a new cam.

Re: 2003 Yamaha F115TR Main Relay Issue

You will probably have to go with YAMAHA for that relay. Guess it is not a high use item. Bought my pump motor from SIERRA for $181, YAMAHA OUTBOARD PARTS wanted better than $550. I can not tell the difference between the two looking at them. My trim relay cost better than $250 thru YAMAHA, had no choice.
Can not see where you would need a boat schematic as all controls go thru the YAMAHA factory wire harness. That way you can hang the motor on any hull. As far as whether the ECU is powered directly thru the key switch or goes thru the relay is a guess right now. From my experience in aircraft, would think it to be common sense to not rely on a relay to power the ECU but to directly power it from the ignition switch. One of those keep it simple stupid things. I would power each independently off the key but what do I know.
Will look at my manual this afternoon. Lots of times a second set of eyes makes all the difference. Happen to me a lot over the years. When you replace that trim position wiper, be sure to place it under the plastic piece on the transducer shaft. Otherwise you will break the transducer, watched a friend do it. regards FRED

Re: 2003 Yamaha F115TR Main Relay Issue

you should check your ISC valve after letting the engine idle for about 5 mins, IF it is pretty hot to the touch, I will guarantee you thats your problem, many of these motors having freaky electrical issues caused by a overheating isc valve.

Re: 2003 Yamaha F115TR Main Relay Issue

Hope this makes sense. First off I am color blind and wear tri-focials so the color diagram was tough for me to read. Appears to me that the main relay always has power standing by at the red wire, hot off the battery buss thru 2 fuses in series. A 30 amp and 20 amp. Yellow wire has got to be off the RUN lug on the ignition switch to energize the relay and tap off at the relay to provide some power to the ECM. When energized the relay powers a GREEN wire that returns to the main harness and I have to assume, provides power for the instruments. If that is the case, it should be of no concern for starting and running the motor, you dont need it.
Now the only other wire coming out the relay is RED/ YELLOW which according to the block diagrams on page 8-15 ( ignition ) and page 8-19 ( fuel control system ) which goes to the ECM. Although it is shown under both fuel and ignition block diagrams, the fuel diagram shows it coming coming back out and powering the electric fuel pump. In my recent experience taking apart the trim relay, you could probably take that one apart and see what is going on. Appears there are also 2 diodes in the coil energizing wires of the relay which also could cause a problem. BUY A RELAY !!
I am at a disadvantage, am spoiled as all the manuals I ever used had a section on description and operation which explained how and why each system worked. Wire diagrams were more detailed with each wire identified by a numbers printed on the jacket with system codes. Good thing since I am color blind. Will also add that MERCURY manuals are much more informative than the YAMAHA books. Hope I have helped. Have had to do a bit of assuming. regards FRED

Re: 2003 Yamaha F115TR Main Relay Issue

Fred, many thanks for studying that for me. You are spot on with the red wire, that is the hot side of the relay contacts. The red/yel wires are the other side of the contacts and therefore become hot whenever the relay is energized.

I agree that the yellow wire seems like it should come from the keyswitch to one of the two diode shared coil connections, but when I buzz it out in my boat there seems to be no contact. This may be the problem.????

The green wire is the other diode shared coil connection. I have no idea where this one is supposed to come from. The two diodes are a clue to me that the main relay can be powered by one of two sources. The diodes prevent backfeed from one source into the other. So if the yellow wire is hot, current can flow in the yellow wire through the coil and out the black wire to ground, energizing the relay. At the same time the diode on the green wire prevents any current from going down the path of the green wire if that is still low. Same can be said if only the green wire is hot. So you end up with an either/or ability on the coil.

So with all those words, I wonder if the yellow wire is suppose to come from the keyswitch to energize the relay, wake up the ECU and then the ECU turns on the green wire to hold the power on the relay and power the gauges too. Would that make sense?

OK, so I will try understand why the yellow wire at the relay doesn't have +12V with the key ON. Also look at replacing the relay.

Thanks again!

Re: 2003 Yamaha F115TR Main Relay Issue

From the prints I look at, The yellow is the power off the key switch. A thing just poped into my mind. Recently a neighbor had a new to him F-90. In his excitement, he forgot to attach the laynard in the kill switch. Motor would start but die when he went back to the run position. FRED

Re: 2003 Yamaha F115TR Main Relay Issue

Well I pulled the harness out tonight. There is not connection on the yellow wire in the harness from the console back to the motor and that is why I cannot get the main power relay energized.

Anyone happen to know where I can get a harness? Or better yet, anyone know the manufacturer of the connectors on the ends?