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ContinuousWave: Small Boat Electrical
Tilt Switch on Mercury Throttle
|Author||Topic: Tilt Switch on Mercury Throttle|
posted 07-29-2006 07:00 PM ET (US)
I have a 2000 90-HP four- stroke Mercury. Got back to the dock today and noticed that the "down" tilt switch (rocker type) on the throttle won't work. The "up" switch on the throttle works and the "down" switch on the engine works fine.
How difficult is it to check/change this switch if that is the problem?
posted 07-30-2006 01:38 PM ET (US)
before you go replacing the switch - get a can of CRC 656 with the little red straw that directs the spray. Spray into the switch and operate it a few times - worked more than once for me....
posted 07-30-2006 11:07 PM ET (US)
Could be switch, could be wiring, could be connector. I'd
start by pulling the connector off under the console and
using a jumper to do what the switch would do. You'll need
a service manual, or some one with access to one, to tell
you which wires to jumper.
posted 07-31-2006 11:46 AM ET (US)
Thanks for the replies. One more thing. The down switch works sometimes. I hate electrical stuff!
posted 07-31-2006 11:50 AM ET (US)
You have two trim solenoids under the motor cowl, one for up, and one for down. You can jumper the two big terminals on the tops of the solenoids and bypass the throttle switch. If the motor trims by jumpering the solenoids, then you know the problem is in the wiring harnes forward to the console. If not, the solenoid is likely bad. BillS
posted 08-01-2006 08:46 AM ET (US)
Basic electrical troubleshooting procedures will help you find the problem.
Begin at the load where you anticipate having voltage. Measure the voltage. If there is no voltage, follow the conductor from the load back toward the source of the voltage. When you reach the next device, measure the voltage. At some point you will find the voltage. You have now found the point from which the problem is downstream. Begin to inspect all devices such as connections, splices, terminals, fuses, switches, circuit breakers, lugs, crimps, etc., looking for some device or connection which has failed. In this way you will locate the problem. When you locate the device causing the problem you can choose to repair or replace the device.
In circuits which operate at 12-volts DC it is very common that a slight bit of corrosion or insulation on a conductor will prevent conduction. With a low voltage circuit the Electromotive Force (EMF) or voltage will not be able to jump through the insulating layer and restore the circuit. In higher voltage circuits the EMF can jump through small amounts of insulating corrosion and self-restore the circuit. With 12-volts it takes but a very thin layer of insulation to prevent flow of current.
Because boats are operating in a wet environment, it is common for electrical connections to become corroded. If you have any bare copper conductors, they will form an oxide of copper which may not be conductive. Silver is much preferred because silver oxides are conductive. For this reason almost all wiring used in a marine application should be tinned and connections should be tinned or silver plated, not bare copper.
Switch contacts should not be cleaned with rough abrasives. Usually a switch contact can be restored by careful cleaning. If an abrasive is needed use 600-grit emery cloth. You can wet-sand with a cleaner like WD-40. The contacts should be very smooth, almost polished.
posted 08-01-2006 11:25 PM ET (US)
There should be a three wire harness coming out of the control box that plugs into a harness on the main engine harness.
Unplug the control box trim harness from the main trim harness. Going to the plug on the main harness, there should be three wires- red in the center, blue and green on either side. Connect a jumper wire with a clip to the red wire ( power )
Touch the blue then touch the green with the jumper. The engine should tilt up and down. If it is intermittent then the switch on the control is suspect.
You can test the switch on the control while you have the harnesses disconnected. Continuity tester to the red and blue, throw the switch, red to green, throw the switch. If you have consistent continuity the switch is probably ok.
I had to do the same as glen e on my old Mercury control. Some CRC 656 a couple time a year kept it going.
posted 08-02-2006 07:31 AM ET (US)
"Touch the blue then touch the green with the jumper. The engine should tilt up and down. If it is intermittent then the switch on the control is suspect."
That isn't right. Should be if it is not intermittent then the switch is suspect.
posted 08-03-2006 04:03 PM ET (US)
Actually the trim/tilt turned out to be a low battery. It was wierd. She cranked fine but the t&t sounded wierd and the down switch was inconsistent. So I went to pull the boat to take it to (Manitou Marine), get in the boat, turn the key, I got nothin'!
So bought a new battery and all is well. I am currently testing the alternator to make sure she is charging. Right now, seems like everything is okay.
I thought she would not crank before the tilt would not work.
Thanks for all the help!
posted 08-04-2006 01:02 PM ET (US)
I haven't done scientific measurements but the starting current demand on small outboards is not as much as you would think (one thinks of a car starter, but take a look at your 90hp starter motor - it ain't much).
Conversely, the tilt/trim motor is a real current guzzler. Just watch your voltmeter drop when you engage it.
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