Trim gauge

[Ernie]

I have a 1993 volvo 5.8 with the SX outdrive. The trim gauge is always pegged all the way up when I turn the key on. It's all the way down, when the key is off. With the key off, I removed the sending unit wire from the back of the gauge and turned the key on, and it still pegs all the way up. With the key on and gauge pegged all the way up I removed the sending wire from back of gauge and it stays pegged. Since the sending unit wire is off the gauge and needle still pegging I'm thinking that it's the gauge and not the sending unit ( I hope ). Any ideas? And do I need a gauge that's for the SX drive specifically, or will something else work. If it's the sending unit, I'll forget about it. If it's the gauge, I'll replace it. Thanks, Ernie

[DickB]

I found this:
http://forums.iboats.com/showthread.php?t=282876

It appears the sender should be reading between 600 and 11 ohms if I understand the test procedure. Disconnecting the sender (infinite ohms) may be equivalent to "up". I would try temporarily connecting a small resistance or even a dead short to ground to the gauge input to see if it moves. If it does, it is probably the sensor or an open connection.

[Ernie]

I did try that proceedure and the needle did not move. I haven't checked with my ohm meter yet. Will try that next. Thanks

[Planetwarmer]

I bet there is a ground issue, or the thing is wired backwards, or even incorrectly. If it is all wired correctly, run another wire to a separate ground.

What I mean is, strip both ends of 1 scrap piece of wire and touch the ground side of the gauge and the other side of the wire to something with a very good ground (like the cig lighter).

This is only to test to see if you have a weak ground. I bet that will solve your problem.

[Ernie]

What you are suggesting is exactly the way I have always tested a gauge. Ground it out and see if the needle pegs. Can't do it with this one because it is already pegged. I have changed wires around to make sure they are in the correct spot and they are. I did try another ground with the same results. However, now that I think about it, I just came off the back of another gauge. May not be a good test since all grounds are leap frogged to all the gauges. I think I'll try a couple of test wires from another battery. That way I can be sure of a good ground. The damn thing just acts like it is grounded out all the time except with the key (power) off. Even with the sender wire off. Thanks Ernie