Mercury Trim Gauge Not Working

Limecc · 02 September 2019, 05:40

My trim gauge began being a bit erratic and then stopped working altogether just before I swopped the engine for a new Merc 40. I was hoping it was the trim sender and was disappointed the fault was still there afterward.

Next I had the gauge out and the resistance seems to vary when tilting the engine (although not by as much as I expected) and there was power to the gauge so I went ahead and ordered a new gauge which I attempted to fit yesterday but that's also not working so must assume it's the wire inbetween.

What should the resistance to ground be in the fully up and fully down positions? How come either gauge doesn't move when I short the trim wire terminal to earth or disconnect it completely? The new engine did come with a sender kit pre-fitted didn't it? Many thanks for your help!

Last Tango · 02 September 2019, 19:08

Is the new Mercury setup for Smartcraft or Analogue Gauges? What came off ?

Limecc · 02 September 2019, 21:41

Quote:

Originally Posted by Last Tango

Is the new Mercury setup for Smartcraft or Analogue Gauges? What came off ?

Analogue same as was first fitted in 2012

Last Tango · 03 September 2019, 14:40

I think you've kind of answered this yourself. I'd try "jury rigging" the trim gauge directly to the sender.

I had a very similar problem with my Honda and it transpired it was a historic petrol leak that had found it's way into the cable trunking and badly degraded all the harness insulation over the years. The transducer on that was powered from a 5v outlet on the management system but it could still be a cabling issue.

Limecc · 03 September 2019, 18:59

After further investigation today I determined that the old gauge was sticking in the fully up position and when I shorted the sender terminal to the earth terminal a sharp tap would flick the needle over to the fully trimmed down position. The ignition needed to be on. I therefore permanently fitted the new gauge which cannot work until I purchase a sender kit for the new engine which doesn't appear to have one. I assume the wires will connect to the engine main wiring harness, there is no separate wire to the gauge.

Limecc · 09 September 2019, 16:16

The new sender 8M0098264 arrived. Covers several models to 60hp. Apparently the latest design is more reliable and better at keeping water out and the ground wire is grounded in the engine instead of at the sender mounting screw.