Temp gauge not working...sort of

[mregan]

Was motoring yesterday. Noticed the temp gauge wasn't working at all.  When I turned off the engine, but still had the key inserted, I noticed the engine temp was around 160*.  Once I pull the key out it drops off.  Put the key in and it starts climbing.  Turn the key to be able to push the glowplug button and temp drops to 0.  The volt meter, gas gauge & tack are all working fine.  I'm assuming something is mis wired in the engine panel?

[Ron Hill]

mre : Has this always been like that?? Or is this the first time??

The temp wire is working from the sender on the engine to the instrument panel.  That brown wire should go to the temp gage.  Pull the panel out and look at the wiring back there. 

[mregan]

Ron,
New boat.  Only had the engine running once before and don't remember noticing the temp issue.  I'll need to check the wiring next time I'm down.

[Indian Falls]

If you can pull the key out there should be no power to that stuff anyway...   so it's not relevant that the key is in the ignition in the off position or not.   You can't remove the key from the switch in the ON position can you?

(don't turn the key to off position with engine running, it's rumored to damage something.  I've done it now and then but nothing happened that I know of.)

Not knowing exactly what you're doing there, the best thing to do is get behind the engine panel and look around for wires touching, and/or loose connections.  Something is fishy about that key in out thing... could be your 3 pos start switch is shot too.

[mregan]

Key doesn't come out when in the on position.

I was thinking maybe water had gotten behind the panel and shorted something.  We had heavy rains from the tropical storm on Friday.  Blower didn't work Sat morning and the buzzer, when you turn the ignition key wasn't working.  Later in the morning I noticed the temp gauge issue.  I'll have to pull it apart this weekend and take a look.

When I have my bimini installed I'm going to have the shop make a sunbrella cover for the engine panel for when I'm away from the boat.

[Ken Juul]

Please make sure you have the wiring harness upgrade done.  If not it could be corrosion issues in the plugs. If you still have the old trailer connectors it is a huge safety/fire hazard.  See the Critical upgrades sticky.

[Stu Jackson]

(don't turn the key to off position with engine running, it's rumored to damage something.  I've done it now and then but nothing happened that I know of.)

Dan, that rumor has little basis in fact.  All turning off the key will do is:  1) turn off your instruments; 2) turn off the power to the regulator on the alternator which will stop alternator output but NOT damage anything.  The ONLY "damage" that can occur is when one interrupts the actual alternator output, which is the BIG + wire from the back of the alternator to the batteries, NOT the key switch on the cockpit panel.  The alternator output (AO) is either run to the C post on the 1-2-B switch (OEM) or directly to the house bank (a modification we strongly urge skippers to make).  See the "Electrical 101" topic in the "101 Topic" sticky.

mregan, good idea to make a canvas cover.  We also used some plumber's putty to seal the top and sides of the fiberglass enclosure to keep water from getting behind the panel.  A dob of silicone would do the same.

[Bobg]

I had electrical issues at the panel and they all cleared up when i changed the switch, I also cut out that trailer type wire connection plug which waS ALL BURNT LOOKING and wired the connections direct, but changing the switch solved my erratic gauge problems

[Ron Hill]

mre : You have something going on in the back of your panel.  You definitely need a sunbrella cover over that engine instrument panel.  I also have rubber boots on the outside of all of my panel switches.

Maybe a shot of "Turner Cleaner" (from Radio Shack) will fix your key switch.  Great Stuff!!

Turning the key OFF while the engine is running :
Stu says it a myth and it is except  -- but if your voltage regulator battery sense wire is connected to that switch!!  If it is it will be like turning OFF the battery selector switch while the engine is running!!!  It's your battery system and you should know how it's wired!

A few thoughts 

[mregan]

Finally got around to checking the temp gauge problem.  Can't figure it out.  Brown wire goes to S, ground is connected to other grounds.  I wire goes to gas gauge which then goes to the start push button.  With no key in temp gauge hovers around 120*.  As soon as I insert key and turn, it goes right to 0.  Disconnected I wire, temp gauge goes dead.  Insert and turn key, temp gauge dead.  Install jumper wire from I terminal to I on tach.  With no key in, temp around 120*.  Soon as I turn key, goes dead.  Any thoughts.  Bad gauge?

[Stu Jackson]

Are you aware of the wiring diagram of the panel here?

http://www.c34.org/wiki/index.php?title=Engine_Harness_Upgrade

[Ken Juul]

Wiring harness upgrade? Yes or No. It can cause so many crazy problems need to know.

[mregan]

It looks like the PO had done a 1/2 wiring harness upgrade.  Removed the wiring harness but never installed a voltmeter.  When I removed the panel for the upgrade, I notice the harness was gone.  Installed the voltmeter according to the upgrade wiring diagram.  The rest of the instrument wiring looks like it does in the diagram.  I think I'm going to have to trace the brown wire to see where it is going.

[Ron Hill]

mre : Take a long piece of #16 wire and run it direct from the temp sender to the gage itself.  There is no-telling how or what color the PO wired it to at the engine end.

At least you can check the gage and temp sender operation and then just run a new wire inside.

A thought