Yamaha 150 - Trim/Tilt lifts engine when ignition key on

[PNM]

Twin 1996 Yamaha 150hp Salt Water series engines. When I turn the starboard ignition key to "ON" position, the starboard engine T/T turns on and raises the engine. This does not occur with the port engine. Standard Twin Binnacle Controls with separate T/T switches and single switch on port control lever which raises/lowers both engines simultaneously. Any thoughts on where the problem is or how to isolate the problem?

 

[fhhuber]

Wires crossed... somewhere between the ignition switch and the tilt/trim motor there's a short.

you could clip and bypass the 2 wires involved with new wires... (may be the quickest solution)

but you need to inspect your wiring harness.

 

[GA_Boater]

Does the TnT switch on the good side raise and lower the motor with the key switch off?

How about the bad side?

 

[will941s]

T&T should operate off the battery circuit, not the 12V running circuit. Which means you should be able to tilt whether the key is on or off. Like other replies, check the relays at the motor for a crossed/short and check the wires coming out the control box and make sure there's not a yellow ACC wire plugged into the harness

 

[GA_Boater]

T&T should operate off the battery circuit, not the 12V running circuit. Which means you should be able to tilt whether the key is on or off. Like other replies, check the relays at the motor for a crossed/short and check the wires coming out the control box and make sure there's not a yellow ACC wire plugged into the harness

That's why I asked?

Has any work been done lately?

Also Welcome aboard, PNM.

 

[Capt Ken]

Now I'll throw a monkey wrench into the mix. Inside the the binnacle unit is two relays, thus the single button can operate both engines while keeping the wires from cross feeding when using the individual buttons. Plus there is blocking diodes in the binnacle harness to stop back feeding. Any problems there can cause the same problem. I've had them drive me crazy plus the blocking diodes aren't shown in any manual.

 

[GA_Boater]

Now I'll throw a monkey wrench into the mix. Inside the the binnacle unit is two relays, thus the single button can operate both engines while keeping the wires from cross feeding when using the individual buttons. Plus there is blocking diodes in the binnacle harness to stop back feeding. Any problems there can cause the same problem. I've had them drive me crazy plus the blocking diodes aren't shown in any manual.

I was wondering about the single switch for both motors. I figured there had to be some isolation diodes or something to allow the OB's to be trimmed separately to fine tune the trim.

 

[99yam40]

If just turning on the key switch causes a T&T motor to run, there would be a short from key on power to the T&T circuit in my opinion.
The T&T system does not depend on key on power so if a switch was stuck it would happen with out the key being tuned on

and if a diode was shorted then both would move

 

[Capt Ken]

And not even Yamaha tech's have a schematic that shows how it operates with the blocking diodes. Don't ask how I know. If a diode fails, you replace the harness.

 

[PNM]

Thanks for all the feedback. No recent work has been done. Both individual T/T switches on binnacle work properly with the key in "OFF" position.
The switch in question (starboard binnacle) does not seem to be stuck in "UP" position. What's the best way to check for a bad switch, short, etc.?
If it works properly in the key "OFF" position, what does that tell you about that same switch in the key "ON" position when the motor starts lifting upward?
If I disconnect the starboard switch at the binnacle and the motor doesn't move up, does that implicate that particular switch as the problem?
If I understand 99yam40 correctly, should the problem be at the ignition / T/T switch connection?

 

[tommarvin]

I'm lost, something is shorted out.

Free factory service manuals at www boatinfo.no/lib/library.html click yam find your motor good luck

 

[99yam40]

From what you have written all switches work properly, so my thought is the wire that gets power with key on(should be a yellow wire I think) is shorted to the wire that tells the T&T to raise the motor. Could be in the harness, harness connectors, controls,or wiring close to T&T relay.

Locating these 2 wires and using a meter should tell you if they are making a connection that is not suppose to be happening. Make sure you disconnect battery power before using meter set to ohms to check for continuity between the wires

Is the T&T relay clicking (energizing)?
If you hit the down switch for that motor just before you turn on the key does it keep the motor from going up?

 

[Capt Ken]

Look under the console and coming out of the binnacle is two pairs of red,green,blue wires and there should be labels stating port -starboard. Unplug the harness for the offending engine. Then raise the cowling on the engine, trace the wires from the trim switch to its connector and unplug. Then turn the key on and see if the engine still rises. If so then you have short somewhere in the harness. If not, then with the key still on, plug in the switch on the engine. If it still doesn't rise, then plug in the wires under the console. If it then rises, the short is in the binnacle.

 

[PNM]

I have disconnected everything (engine switch and all switches from binnacle) and still have same problem as long as the 8-pin harness is connected.
Disconnect the harness, problem solved.
I even connected stb harness to port ignition????..key ?on?, stb motor goes up.