[BobFreyHomes]

Hi fellow Mariah Boat owners!

I have owned my 1994 Mariah Talari since about 2010. It has been a great boat! It is a Z210 (do ihave that right?) and it has a Volvo Penta DP-D1 stern drive with a 7.4l engine, duo prop.

Ever since I owned it, the trim gauge has not worked. I took a shot at trying a new potentiometer (sender) but to no avail. No change to anything with the new sender. I did a comparative ohms test between the two senders and they both do just about the same thing. The sender has three wires. The gauge moves down slightly from off the upper end of the scale to full up position when turning the key on. I tried grounding the sender terminal on the gauge and the gauge falls to the down position, indicating the gauge is not the problem.

I looked at some wiring diagrams found here on this forum (for a similar but not the same boat) and it looks like the wiring goes through a device called "8 way" on the diagram. BTW, the diagrams I looked at, the items on it are not labeled that well. I have a device on my boat that the sending wire from the gauge connects to that has an adjustment knob. I am assuming that is the same as the device labeled "8 way" on the diagram? It seems that this device may be used to dial in the ohms form the sender to make the gauge range and read properly. if my assumptions above are correct:

1. Does anyone have a troubleshooting procedure for the "8 way device"?
2. Can they be purchased new?
3. Does anyone rebuild/service them?
4. Any idea where I can get a manual and wiring diagram specific to my boat?
5. What do the 3 wires on my sending unit do and go? I would think one would be ground, one would go to the gauge (with the "8 way device" in between). What is the 3rd lead for?

Any help is greatly appreciated!

Bob