Temperature gauge not working

[brad614]

I have a 2004 Larson with the 5.7 Volvo-Penta Duo Prop setup. The temperature gauge worked fine, and then it stopped. It then started working again for about 5 minutes, and then stopped and now won't work at all. I have checked the connections at the gauge, and they all look fine. I checked the connections at what I believe is the sending unit (in the front of the engine at the top near what I believe is the thermostat housing), and those connections look fine too. What can I do to test the gauge and sending unit? Is there anything else it could be?

 

[Don S]

Re: Temperature gauge not working

Disconnect the temp sender wire, turn the ignition switch to the run position (engine not running) and tap the sender wire to a good clean ground. The gauge should peg to high. DO NOT hold the wire on the ground for more than a second, just tap it and see if the gauge jumps.

If the gauge works, replace the sender.

 

[brad614]

Re: Temperature gauge not working

Disconnect the temp sender wire, turn the ignition switch to the run position (engine not running) and tap the sender wire to a good clean ground. The gauge should peg to high. DO NOT hold the wire on the ground for more than a second, just tap it and see if the gauge jumps.

If the gauge works, replace the sender.

I will try that when I go back to the boat. But there is actually a harness with two wires. I guess I should try each one?

 

[brad614]

Re: Temperature gauge not working

OK - where is it located? The two wire unit on the thermostat housing isn't it. I called the dealer and they can't even find the part in their catalogs!

 

[Don S]

Re: Temperature gauge not working

OK - where is it located? The two wire unit on the thermostat housing isn't it. I called the dealer and they can't even find the part in their catalogs!

Have no clue, what's the full Model number or serial number of your engine. Year doesn't mean a thing and 5.7 is just to general and too many variations.

 

[brad614]

Re: Temperature gauge not working

The model number is 5.7 Gi-E, and the serial number is 4012121892.

 

[brad614]

Re: Temperature gauge not working

Update - the local dealer found the part (#3852029), but even they can't tell me where it is located on the engine!!

 

[Don S]

Re: Temperature gauge not working

Ok, you have EFI, not carbed. The test procedures I gave you aren't going to work. Sounds like you have the newer EGC system, and there is almost no info on it.
You have what is known as an ECT (Engine Coolant Temp) sender that feeds the ECM, which in turn talks to the instrument panel. The ECT has two wires to it. a tan/white wire and a black/lt.green wire. Do not just short them out.
Do you have any running problems? Like running too rich or anything?
What you really need to do is get a diagnostic computer hooked up on your engine and see if the ECT is giving proper info to the ECM. If it is, then you have either a wiring problem from the ecm to the gauge or the gauge itself is bad.

You can take the sender wire off the gauge, and with a jumper wire, touch the ground and sender terminals on the gauge and see if it peggs the gauge. if not, you need a gauge. If it does, you need to check the wiring between the tan wire on the gauge and the tan wiring going from the dash to the ecm for continuity.

 

[brad614]

Re: Temperature gauge not working

Thanks Don! I have absolutely NO problems - boat runs like a dream! Just did all of the maintenance including a new impellor, so all that is good. To clarify, the tan wire is going to be the sender wire?

 

[Don S]

Re: Temperature gauge not working

To clarify, the tan wire is going to be the sender wire?

Well, yes and no. It's the sender wire on the back of the gauge and one of the terminals on ECM harness, but it is not on the temp sender that is located on the engine.

 

[brad614]

Re: Temperature gauge not working

OK - I checked it as you suggested, and nothing. When I short the sender terminal to the ground nothing happens. When I check across the other two terminals with a test light I have power with the ignition on. So I am guessing it must be the gauge, correct? If so, my next question is how do I go about getting a replacement gauge? Will anything work, or does it have to be "in tune" with the current sending unit setup? I have attached a picture of my current gauge. Obviously, I would like to get one that matches as closely as possibe, but I can't find a brand name on any of the guages.

 

[Thalasso]

Re: Temperature gauge not working

OK - I checked it as you suggested, and nothing. When I short the sender terminal to the ground nothing happens. When I check across the other two terminals with a test light I have power with the ignition on. So I am guessing it must be the gauge, correct? If so, my next question is how do I go about getting a replacement gauge? Will anything work, or does it have to be "in tune" with the current sending unit setup? I have attached a picture of my current gauge. Obviously, I would like to get one that matches as closely as possibe, but I can't find a brand name on any of the guages.View attachment 140817

This might be what your looking for. Faria Kronos Instruments. You can get it here on iboats

 

[brad614]

Re: Temperature gauge not working

Thanks. That's close, but still not quite it. Seems like everything I ever need is an oddball!

 

[Don S]

Re: Temperature gauge not working

Call Larson, and have your HIN with you.


http://www.teleflexmarine.com/products/instrumentation/instrumentation/lido/

 

[brad614]

Re: Temperature gauge not working

Quick update on the resolution - after searching forever, I finally found a matching guage. Installed it Saturday and everything is back to working correctly. Thanks to everyone for their input and advice!

 

[Don S]

Re: Temperature gauge not working

Quick update on the resolution - after searching forever, I finally found a matching guage. Installed it Saturday and everything is back to working correctly. Thanks to everyone for their input and advice!

One would have thought you might have mentioned who's gauge it was and what model :facepalm:

 

[brad614]

Re: Temperature gauge not working

I would have if I knew! I finally got in touch with someone at Larson and they were able to match it from my HIN. It was the only one they had left, and there wasn't any name on it. The guy didn't know either.

 

[Don S]

Re: Temperature gauge not working

That's the info needed. It's probably a Larson design and that's the only way to get a match. Now others will know.
Thanks.