Temp gauge acting wierd...gauge or sending unit?

[pig140]

I have a 2001 Launch SSV and I just took it out for the first time this summer (lots of flooding here, finally the water is going down). I noticed the temp gauge acting wierd. Most of the time it just lays there dead not reading anything. Then every now and then it pops up and reads what it supposed to, but only for a few seconds. It never reads over normal when it actually reads.

Where do I start? Does this sound like something lose or something going out? Thanks in advance for any advice.

[FoiltechLaunch21V]

I would check the connection(s) at the gauge and the sending unit. First.

[Salty87]

agree with foiltech

you can also test the sending unit by removing its wire and grounding it to the block. if the gauge pegs, it is ok and either your wiring or sending unit are bad.

[csuggs]

My experience is that most of the time intermittent problems like that are caused by a bad ground somewhere. If there is only one wire coming off the sending unit, then it is grounded through the engine block and the one wire is your signal wire. You can then check to see that the gauge is grounded (should be a common ground wire in the gauge cluster)

[pig140]

Thanks guys! I found a loose wire around the sending unit. I hope that fixes it. Took the boat out today only to find the battery was drained again, so not sure yet. I guess a battery is something else to add to the list this year. The RPM gauge quit last year, the PerfectPass servo motor is seized, and the steering cable needs to be replaced.

At least (I hope) I can scratch that temp gauge of the replacement list. You guys have any suggestions why my RPM gauge quit on me?

[Salty87]

You guys have any suggestions why my RPM gauge quit on me?

i gotta go with another loose wire

[csuggs]

You guys have any suggestions why my RPM gauge quit on me?

A loose wire, and check the grounds. That could be the problem with both gauges!

[pig140]

OK, tested the battery, its good. Looks like the starter. Still trying to trace those wires on the RPM gauge. This is just one of those years.

[mapleleaf]

For me it's so much more fun than working on somebodies house!!!!
turns out I should pick a new career....

[DKJBama92Mariah]

IIRC the tach wire is grey and leads to the negative post on the coil. Check the connections, the +12v and the grounds.

On the power and ground connections to the gauges, mine were just daisy-chained from one gauge to the next using jumper wires with ring terminals. If one of the nuts holding these jumper wires onto the post backs off, It can throw several gauges off at the same time. I finally gave up and just made my own harness with an independent power and ground wire for each gauge.

Get yourself a nutdriver of the appropriate size to tighten the nuts on the back of the gauges. It's MUCH easier than trying to squeeze a wrench in there. I just used a 1/4" drive screwdriver handle with the approriate socket.