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View Full Version : circuit board behind the dash, what does it do? -- 88 PS 190


hardycm
07-20-2011, 08:11 AM
I had a recent problem with my ignition that I think was due to a failing ignition switch. I changed that out last night and the boat runs. But, since its an intermittent problem I wanted to look at other things that might prevent me from getting 12 volts to the coil in "run" (which was the main symptom, I think). Tracing the wiring, it looks like the 12 volts in run doesn't come directly from the ignition switch, but actually goes through the gauges, which each have leads going to a circuit board behind the dash. The purple wire that leads to the coil + post then comes off of this circuit board as well.

Does anyone know what "logic" happens in this circuit board? Does it do anything beyond just sounding the buzzer for temp or oil pressure warnings? Can it force the engine to shut off? For example if the temperature is high or oil pressure is low, could this board interrupt the 12 volts to the coil? I've considered running a seperate line from the "run" post on the ignition switch straight to the + post on the coil. Any reason this would be a bad idea? BTW, the previous owner removed the kill switch so good or bad, that's out of the equation.

Thanks,

Chuck

j.mccreight@hotmail.com
07-20-2011, 08:23 AM
the circuit board is just an audible alarm for oil, water, voltage etc, they can fail usually the alarm will not turn off, it will not interfere with the operation on these systems. You could run a new wire from the switch to your coil, however if you have a ballast resistor you still need use it, you could remove the board completely from the circuit and everything will work. post a picture to make sure were talking about the same board.

hardycm
07-20-2011, 08:39 AM
Thanks for the quick reply. After I posted, I found the post by RyanMojo and the pic he shares is the board I'm referring to. I have the electronic ignition, so no ballast resistor. I think I'll wait to see if the problem recurs, but wanted to make sure I've got all the bases covered in that event. These intermittent problems are great fun -- as on owner of an '89, I'm sure you can relate.

Dino Don
07-20-2011, 09:20 AM
Thanks for the quick reply. After I posted, I found the post by RyanMojo and the pic he shares is the board I'm referring to. I have the electronic ignition, so no ballast resistor. I think I'll wait to see if the problem recurs, but wanted to make sure I've got all the bases covered in that event. These intermittent problems are great fun -- as on owner of an '89, I'm sure you can relate.

I have a 87 that this past weekend would continue running after I turned the switch off. Tried many times but would not turn off. Used it for a long while running and then just tried it again and it turned off and worked fine until we pulled it out. Yours do anything like that???

Put a new electronic conversion on it and was going to remove the ballast but there is an orange wire that feeds off the back post and I did not know where it went--so I left it connected through the ballast. Was yours like that also?

hardycm
07-20-2011, 10:30 AM
I've never had that issue, but it sounds like maybe an issue w/ the ignition switch (maybe I'm biased toward that b/c I just replaced mine). Regarding the orange wire, are you talking about a wire from the solenoid to the coil? If so, that is the wire that gives you 12 volts during cranking and was needed for a points system. Do an internet search on cranking bypass or similar. I completely removed my ballast resistor, so I think there are 5 wires connected at the + post of the coil. They go to the electronic ignition, alternator, choke, solenoid, and ignition switch if I remember correctly. I think you could completely remove the orange wire, but left mine.