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ContinuousWave: Small Boat Electrical
Accidental Short Circuit Blows Fuse; Trim-Tilt Problems
|Author||Topic: Accidental Short Circuit Blows Fuse; Trim-Tilt Problems|
posted 12-17-2009 12:13 AM ET (US)
To all mechanics: I've been helping my brother with a problem were having with a 1989 Johnson 90-HP engine. The engine was running perfectly. We had the gauge cluster out of the console, and the gauge for the trim and tilt was disconnected. We started the engine, and, as the engine was running, a green wire and a gray wire off of the trim gauge touched. There was a small spark, and the engine kept running for another five minutes.
I shut the engine down, tried to restart, and nothing happened. No crank, no beep from the alarm, no voltage showing on the voltmeter--just a dead engine. What might have shorted out? Is there a fuse that needs to be checked? Is the ignition switch toast? Or possibly the power pack? I just don't know. All connections are good, brand new battery, and, as I said, the engine was running perfect until that point. Any help on this will be greatly appreciated. If more info is needed let me know and I will give as much as possible.
posted 12-17-2009 03:20 AM ET (US)
Went through a parts catalog and found the fuse I was looking for in the ignition wiring. Now the engine will crank, the voltmeter works, and the alarm sounds when the key is turned. My only problem now is that the trim and tilt will not work. I think the problem is the relays.
Is there anything else in the trim and tilt wiring that could have been affected by the shorting of those two wires from my original post. After looking at the diagram on Ishopmarine.com I can't find anything. Any thoughts on this next phase of our problem. Plan to buy two new relays tomorrow. Again any info is appreciated.
posted 12-17-2009 08:03 AM ET (US)
It would be very unlikely that a temporary and very short duration short circuit in the wiring to the trim gauge would cause the simultaneous failure of two relays that control the motor for the power tilt.
When a short circuit occurs there is often a protective fuse which will be blown. Search for a fuse in the circuit that feeds the trim control switches with power.
Check for power at the relays for their coils; check for power at the relays for the high-current circuit that is switched by the relays.
posted 12-17-2009 08:05 AM ET (US)
Often there are two sets of control switches that operate the relays. Check to see if either set of switches is still working.
Diagnosis of this problem is really straightforward for anyone who understands DC electrical circuitry. You just need to look for voltage at the relay coils and contacts.
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