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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10902
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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I have a 2002 Maxum SCR 3100 and it has a Jabsco electric

Customer Question

Customer: I have a 2002 Maxum SCR 3100 and it has a Jabsco electric flush 12 volt toilet. When I press the flush button switch nothing happens. I took wires off switch and tested voltage and their was no power to switch. Breakers are on and I could not find a fuse which I was told might be behind the battery on off switches so I do not know what steps to take next
JA: Thanks. Can you give me any more details about your issue?
Customer: The boat only has 120 hours on it and the survey done on boat prior to me purchasing it a few months ago said everything worked fine. I am not sure if I am missing something simple... I thought there should be power to the switch no matter what but I could be wrong
JA: OK got it. Last thing — Marine Mechanics generally expect a deposit of about $26 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: Boat
Customer: replied 1 year ago.
Okay I went to pay the deposit on paypal but noticed it charged me the full $26 which I paid and not the $5 it said it was going to charge me...I understand and will be happy to pay the $26 if my issue gets resolved however a little concerned why it said it would charge $5 for the deposit and this wasn't the case... anyways if I get this toilet figured out I don't care it has been really boggling me.
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

Have you checked the fuses in the fuse panel? There should be voltage to the switch all the time.

Now do the other 12 volt accessories work correctly? Do you know if the house battery is fully charged?

Customer: replied 1 year ago.
I checked every breaker, every fuse, and every single other 12 volt item works as it should. All three batteries are fully charged and hold great voltage under a load. Another tech told me there would not be power to the switch unless toilet motor signaled it to do such. I did not understand that at all...
Expert:  Tan replied 1 year ago.

Did you check voltage at the circuit breaker both terminals.? You could have a bad circuit breaker? The switch to the head should have 12 volts.

Customer: replied 1 year ago.
All I have is a panel with resettable red push buttons and I unscrewed that panel board and it did read 12.7 volts
Customer: replied 1 year ago.
All other switchable breakers do function and shut off specified items. There is not a separate circuit breaker for head in cabin only the push button one I spoke of in cockpit under steering wheel.
Customer: replied 1 year ago.
if motor were bad I would still have 12 volts to the switch is what I hear you saying and that is what I figured. I also went as far as following wires from circuit but could not get all the way as they disappear in fiberglass walls as I wanted to do a continuity check for break in wire which I find highly doubtful
Customer: replied 1 year ago.
Do you know on a 2002 Maxum SCR 3100 where the fuses and breakers should be located for the head. There is not an actual breaker button or circuit breaker or fuse specifically labeled for the toilet/head... I did though test all I see including accessory circuits etc...
Expert:  Tan replied 1 year ago.

12.7 on both terminals of the breaker? Those type breakers are notorious for going bad. If you have voltage then you will have to trace the wire down and find where you are loosing voltage from the breaker to the switch at the head.

There is a plug for the harness wiring going to the head. I don't have a manual on your model boat so I can't tell you where the plug is. The wire color should be a brown wire with a yellow stripe. We also need to check the ground going to the head. The ground will be a yellow wire. Have you tested the wires at the head for voltage with a voltmeter. If the head motor is bad you can have voltage and it won't work so we need to verify that you have no voltage for sure on the brown/yellow + and the yellow - wires.

Customer: replied 1 year ago.
There were only wires coming up through the fiberglass floor of boat and going directly into the motor.. I took shell of motor off and their was no power to those wires either. As for the breakers every breaker has power and none are actually labeled for the head but I assume the shower pump could be the same one or an accessory breaker but again all have power. I had narrowed things down to tracing a break in a bad wire myself and attempting a continuity test but the wires are buried and fished in a way that I could not get the back in or run new ones...
Expert:  Tan replied 1 year ago.

Ok you are on the right track it is just a matter of finding the break in the wiring. You are most likely going to find a corroded connection. I have done about all I can do without being there to find the problem. Electrical issues are impossible to find over the internet. These are just something you have to look for.

Without a wiring diagram there isn't much more I can tell you on this issue.

Check all the harness plugs for the accessory wires it could be just a corroded connection or possibly a burnt connection. The head pulls allot of amperage and I have seen them burn connections from resistance.

Customer: replied 1 year ago.
Oh I also took a 12 volt jump box and put power into the wires that went to the switch to see if I could get the motor to turn and got nothing from that either.
Expert:  Tan replied 1 year ago.

That tells me the head motor is bad. Have you tested the wires at the head motor with a volt meter?

Expert:  Tan replied 1 year ago.

Connect the voltmeter between the yellow ground and the brown/yellow positive do you read voltage with head switch activated?

Customer: replied 1 year ago.
no power... Also I did check all connections this boat was stored inside heated area its whole life it has 130 hours on it approximately everything is like brand new... That is where the confusion lies also. I had narrowed it down to a break in a wire as the only candidate I could think of but when also running direct power to switch wires did not do anything I eliminated that as a likely candidate as I was told there would not be power to that switch at all times due to possible clogs in pressure pipes etc... hence me seeking your help
Expert:  Tan replied 1 year ago.

What is the model of this head?

Expert:  Tan replied 1 year ago.

Clogs won't keep power from going to the head. The switch runs the motor which pumps waste out and water in. Therte is no pressure on discharge side of the head.

Customer: replied 1 year ago.
The absolute only thing its says on it invisible sight is Jabsco and the motor is a 12 volt... That is what I would have thought too but when I googled about the power it did say there is a sensor cutoff if a clog is detected on some heads.
Customer: replied 1 year ago.
I am not saying this google information is correct... Web MD always says I am dying when I put in my symptoms lol
Expert:  Tan replied 1 year ago.

Never heard of a switch to shut off when clogged.

Can you post a picture of the head?

Does this look like your head?

Customer: replied 1 year ago.
Similar of course but no not the same my motor is black and in the back has no white plastic cover over it. Shape of toilet a little different but similar
Expert:  Tan replied 1 year ago.

Ok I need to determine what model head you have. But we are still having a voltage loss issue. So we have to follow the wires. I can't do much more to help at this point. I will opt out maybe another expert can help.

Customer: replied 1 year ago.
Okay thanks...

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