HELLO! I am looking for the wiring schematics for my 1985 Chaparral 234. I am having an issue with my gas gauge and would like to see if it is possible if I have a short. The engine is a 225 Mercruiser. Not sure if that info is needed. Any help would be greatly appreciated. Thanks in advance!!
Unfortunately, you're not going to find boat-specific wiring diagrams. You will be able to find generic engine diagrams, which include dashboard diagrams. Using your engine year and model, download a few engine manual from sites such as 4share.com. Then look for the dash/guage wiring diagram. Basically, a gas guage works on a one-wire/ground system. A positive source goes to your guage and a ground wire gores to the variable resistor attached to the float in your tank. It's similar to the float in your home toilet tank. To test the guage, disconnect the ground/sender wire at the guage. Connect a wire from that terminal to a ground. Your guage should read full. If it doesn't, you have a faulty guage. Disconnect the wire. The guage should read empty. If not, again, a bad guage. If the guage is OK, reconnect the sender wire and disconnect the wire at the gas sending unit at the tank. Ground that wire and the reading should be at full. Disconnect from ground and the reading should be empty. If not, shorted or open/torn wire. If all that's OK, and it probably will be, the sending unit is bad and needs to be replaced. That's a rather commom problem, particularly on older boats. Replace the sending unit, which is available at most marine supply stores. Hope this helps. PS.: Shoot over to the Chaparral owners forum at yahoo. There are many knowledgeable and friendly Chaparral owners there, and newbies are welcome. See you there. Hy