Kevin,
I recently bought a used boat. It was improperly grounded and burned some of the boat wiring out. My mechanic repaired several problems, but one problem still remains.
When you switch on the ignition most gauges jump to their maximum. For example the trim is maxed out to the right no matter at what level the outboard really is. The oil pressure gauge does nothing. The tachometer goes clear to the right. The speedometer goes to about 10 miles an hour and stays no matter what speed the boat is moving.
Other electric things work correctly, such as the horn, the starter motor, the trim mechanism, bilge pump, bilge blower, and so forth. The stereo system, the marine radio, and GPS seem to be non-functional.
What is that it that can cause all gauges to fail like this? By the way, the boat is a 2002 Chaparral 180SE with a Mercruiser 3XL engine and outdrive. The boat has been badly mistreated, and has required a lot of work to get it functioning again.
Thanks for any suggestions you can give.
Steve
Hi Steve,
It sounds like you have a combination of marine electrical problems.
My guess is that you have more burned out wires.
You should start by checking for 12 volts at each gauge. + on purple and – on black
Then, using an ohm meter check the following
- Trim position – brown/white – 60 ohms down 11 ohms up
- Oil pressure – lt blue – over 240 ohms 0 psi 33 ohms 80 psi
- Fuel – pink – over 240 ohms empty 33 ohms full
- Tach – gray – test for continuity through harness to engine
As for the speedo, check for a plugged or melted pitot hose, if so, replace the hose. You should also clean up the pickup and check for a bent axle on paddle wheel
Hope this helps,
Kevin
