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BrianM
03-19-2006, 05:39 PM
Temp guage on my boat has decided not to work. Need to get some tips on how to trouble shoot. The sending unit is just a few hours old so that is not the problem. Gauge was working good Tuesday but today I have nothing. Checked all of the connections and everything seems tight and clean. So how do I check the guage to see if it is or isn't working properly and then how do I check the wire to the sending unit to make sure it is ok? When I turn the key on the gauge actually moves a little lower and then stays there (so it is obviously getting power). Checked the thermostat to see if it was staying open but it was closed when I pulled it out (after a few sets of skiing) so that seems like it should be OK. I am probably going to replace it anyway just to rule that out. Boat is running great impeller is new and exhaust risers are warm not hot after running so operating temp seems right on. Guage just isn't reading. Help please..........

JimN
03-19-2006, 07:26 PM
Look for a sensor with a tan/black wire gong to it. That's the sensor for the gauge, not the ECM. Turn the key to ON and with the wire removed from the sensor, connect it to bare metal on the motor. The gauge should be pinned to its highest point. If it does this, either there's no water getting to the sensor, or the sensor may be bad. If it does nothing, either the wire or the gauge is bad. First. wiggle the wire and if you have a multi-meter, you can test the resistance at different temperatures by putting it in a pan on the stove.

BrianM
03-19-2006, 09:21 PM
Look for a sensor with a tan/black wire gong to it. That's the sensor for the gauge, not the ECM. Turn the key to ON and with the wire removed from the sensor, connect it to bare metal on the motor. The gauge should be pinned to its highest point. If it does this, either there's no water getting to the sensor, or the sensor may be bad. If it does nothing, either the wire or the gauge is bad. First. wiggle the wire and if you have a multi-meter, you can test the resistance at different temperatures by putting it in a pan on the stove.

Thanks Jim. I just replaced the sensor less than 10 hours ago so I am assuming that it is good since the guage was not working prior to replacement but since then it has worked fine. I will try the test grounding the wire and see if the gauge responds. When I pulled the guage out to take a look I think there was just a blue wire and then the power wires. Is that blue wire the same as the wire that is tan at the sensor? I am assuming if you remove the imput wire from the rear of the gauge and then ground out the connection to the guage with the key on that it should peg, thus eliminating the wire to the sensor as the issue? The sensor does have water on it. I pulled it and there was water in the hole.

JimN
03-19-2006, 09:32 PM
That blue wire is the light for the gauge, just like all gauge lights. There will be a purple (key on power), black (ground), blue and the sensor wire. There's supposed to be water in the hole- that's how it knows the temperature of the coolant. Water on it would make it peg if it got on the wire and grounded it.

You replaced the same sensor or was it the two wire sensor for the ECM?

BrianM
03-19-2006, 10:28 PM
That blue wire is the light for the gauge, just like all gauge lights. There will be a purple (key on power), black (ground), blue and the sensor wire. There's supposed to be water in the hole- that's how it knows the temperature of the coolant. Water on it would make it peg if it got on the wire and grounded it.

You replaced the same sensor or was it the two wire sensor for the ECM?

Thanks for the color of all of the wires on the back of the gauge. I was looking from the side so I could only see the blue and the purple. If I get nothing from grounding the sensor wire I am going to pull the gauge completely to make sure that the sensor wire didn't come loose from the back of the gauge.

Oh and above I meant water in the hole not on the hole. Sorry for the bad explanation. Everything with the water level and temp in the block was OK

I replaced the sensor that has the single brown wire attached. When I bought the boat it was bad and BAWS had test checked it and sent me the replacement part which I installed. Has been working great until now.

BrianM
03-20-2006, 01:12 PM
An update to those that care. Followed JimNs instructions on trouble shooting the gauge and found that the gauge is bad (Thanks a lot for the help Jim). I check my methods on my friends '97 205 and his tested good so I know my method worked. So new gauge is the answer except for one small problem Mastercraft no longer has them.

So I spent the morning calling around to dealers to see if someone had one left on the shelf. All of the usual suspects BAWS, MyMC, Rambo (closed monday), and a slew of others all to no avail. Finally found one at Cope and McPheters in Rocklin, CA. Props to them for having some old stock. Sending it out Fed Ex today so I should have it in my hands by the weekend.

In all of my searching I did find a place that could repair if needed although it was a little cost prohibitive (about $150) but they said they can fix anything. So any of you wanting to keep a stock look and have a broken guage there is a source for repair http://www.lspeedo.com/

tommcat
03-20-2006, 06:49 PM
just a quick note to the testing method. it's best to ground it out through a test light as some gauges dont like a direct short to ground and it can damage the gauge. not always but it's best to play it safe. it will also let you know if you even have power on the wire.

BrianM
03-26-2006, 06:19 PM
Got the new guage on Friday and then installed yesterday. Everything is working great now. Glad I was able to find an original gauge. Thanks again JimN for the how to on troubleshooting the thing.