Alarm going off with just key on

[willietm5]

I have an 04 150 Yamaha TXRC, with very few hours, the motor has always ran fine. Just had it service about 2 months ago. I put it in the water a week ago ago and as soon as I turned the key on the alarm starting going off, motor started right up seem to run fine, but alarm still going off. Put it in gear to turn boat around and it had no power, would not go, back on the trailer. Both oil tanks are full and had a good stream of water coming out with motor running. Took it to my mech. He told me the CDI unit is bad. He unplug all the sensors, alarm still going off with just the key on. Plug them back in and unplug a 10 wire connector off the bottom of the CDI unit and the alarm stopped. Before I spend 900 to 1000 bills, can anyone point in another direction of what may be wrong? THANKS.

 

[rodbolt]

Re: Alarm going off with just key on

post the full model number, the 150TXRC was made in about 6 configurations that will be identified by a prefix alpha character.
I would continue testing.
ECU failure is very rare.
does your hull have a water detect filter? has the engine been upgraded for water detect??
what indicators are lit on the tach and speedo?
if the ECU detects low voltage it can set an alarm,if the ECU detects the oil switches in the engine tank are unplugged,or a bad wire, it sets the alarm.
the early HPDI motors prior to 05 had water detect switches that can trigger an alarm.

 

[willietm5]

Re: Alarm going off with just key on

post the full model number, the 150TXRC was made in about 6 configurations that will be identified by a prefix alpha character.
I would continue testing.
ECU failure is very rare.
does your hull have a water detect filter? has the engine been upgraded for water detect??
what indicators are lit on the tach and speedo?
if the ECU detects low voltage it can set an alarm,if the ECU detects the oil switches in the engine tank are unplugged,or a bad wire, it sets the alarm.
the early HPDI motors prior to 05 had water detect switches that can trigger an alarm.

I wish I had the prefix alpha character handy, but I don't, I am at work for the next 7 days. This motor is on a 22 ft. Blazer Bay. I have no water detect filter and the engine has not been upgraded. No Indicators are lit on tach and speedo. Thats what my mech. says that ECU failure is rare and this motor has less than 100 hrs. on it. He did test the oil and temp. sensors, but not for low voltage. He did not say anything about water detect switches. I know the motor will start right up and seem to run fine on a water hose but no power when in the water. As i said the only thing that will make the alarm go off is to unplug the 10 wire connector on the bottom of ECU and the motor still runs. Well also the alarm goes off when you turn the key off.

 

[rodbolt]

Re: Alarm going off with just key on

as it has 2 oil tanks it narrows it down to HPDI,OX66 EFI or a carbed version.
the 10 pin plug also contins the inputs from the various sensors as well as the outputs from the CDI to the alarm horn.
by unplugging it you not only eliminated the inputs but the output as well.
if all else fails have him install a new CDI unit while you watch,if it works pay the man,if not he now owns a spare CDI and he can keep hunting.
but on that one I would wish to watch the replacement.

 

[willietm5]

Re: Alarm going off with just key on

Thanks for the advice, I think first I will have so more testing done. If else fails, I like what you said, change it out with me watching.