90Hp trim gauge reads backwards !

[spunkyman]

I have a 2002 Glastron SX170 with a same year Mercury 90hp (ELPTO) O/B. When I bought the boat, it didn’t have a trim sender and the gauge did not work. I bought a brand new trim sender kit (Quicksilver 821400A 2) and a (what I think) was a direct replacement Faria trim gauge (CS0331 stamped on the back of old and new trim). I hook everything up, brown/white sender wire and ground. Gauge reads backwards - down when motor is up and up when motor is down. From what I understand, I have the correct parts. Is there something else getting in the way here ? I’m dumbfounded. It’s all Merc parts !?!?!

 

[Chris1956]

Are the power and ground wires switched on the gauge? Did you switch them on the battery?

 

[spunkyman]

Are the power and ground wires switched on the gauge? Did you switch them on the battery?

No. Ground in the middle, purple on ignition and brown/white on sender. As for the supply to the gauge, it’s coming from the cluster of dash wires. At the battery, I don’t believe it’s a separate hook up, it’s just part of the wiring harness. At the motor, all wiring is correct as far as blue/white and green/white going to their respective places. All other gauges work as they should.

 

[Chris1956]

Well, the only other alternative is that the trim sender is installed incorrectly. Not sure how that would happen.

You could reverse ground and power at the gauge. I would think that would work...

 

[spunkyman]

Would that not cook the trim gauge ?

 

[Chris1956]

I do not think so, but it is not solving the problem. The real solution is that either you have the sender installed backward, or the gauge and sender are incompatible. You might consult the specs on each and see what reading zero ohms is supposed to give. Then do the same for max ohms.

 

[spunkyman]

I’ve just realized that this, even though it has the same casing number (CS0331) that doesn’t mean all of the guts are the same ! This is a 13123 which is OMC. I require the 13122 which is Merc ! Duh … but good to know for others reading this !! Thx Chris for your help.