Question about voltage at switch panel

[beernutz]

My boat sat unused for 9 months with a dual bank trickle charger on the batteries. When I finally was able to crank it on dry land using a muffler the switch panel (see part 1142314 below) which runs the light, horn, etc would not respond. I took the boat to my local marine mechanic who said the switch panel was fried and needed replacing.

I obtained a replacement part from Sea Ray which was pricey but necessary, however, now as the mechanic is installing the new switch panel his multi-meter is measuring a small amount of voltage on the black ground wire (see DC wiring schematic below). Since he's not sure at this point what caused the switch panel to fry previously as no fuses in the fuse box were blown he is hesitant to proceed further.

Any thoughts or suggestions on how to proceed are most welcome.

 

[JimG]

Although I can't make it out on you pictures (not enough resolution), I believe that the keypad interfaces to the ECM (Electronics Control Module) with a serial connection... it is likely that he is measuring the communication signal. That's how you get 9 function on 6 or so wires.

That said, I hope your problem is in the switch pad and not the ECM (more likely).

 

[beernutz]

Although I can't make it out on you pictures (not enough resolution), I believe that the keypad interfaces to the ECM (Electronics Control Module) with a serial connection... it is likely that he is measuring the communication signal. That's how you get 9 function on 6 or so wires.

That said, I hope your problem is in the switch pad and not the ECM (more likely).

Sorry about the poor resolution, the wiring diagram can be seen on page 18 here better: http://www.searay.com/boat_graphics/electronic_brochure/Company1729/1C1_23_74DEJAK1R3A.pdf

I am no expert in this sort of thing but it appears that
EIM pin 1 connects to Switch pin 6 with 12v,
EIM pin 24 connects to Switch pin 1 with 5v,
EIM pin 14 connects to Switch pin 3 for TxRx+,
EIM pin 12 connects to Switch pin 4 for TxRx- which I assume are the serial connections,
EIM pins 15,17 connect to Switch pin 2 for ground.

I am going over to take a look at the boat this morning with the mechanic to understand better what is happening.

 

[Lazy Daze]

Does the main feed (+12v) wire behind the dash have good voltage?

 

[JimG]

Sorry about the poor resolution, the wiring diagram can be seen on page 18 here better: http://www.searay.com/boat_graphics/electronic_brochure/Company1729/1C1_23_74DEJAK1R3A.pdf

I am no expert in this sort of thing but it appears that
EIM pin 1 connects to Switch pin 6 with 12v,
EIM pin 24 connects to Switch pin 1 with 5v,
EIM pin 14 connects to Switch pin 3 for TxRx+,
EIM pin 12 connects to Switch pin 4 for TxRx- which I assume are the serial connections,
EIM pins 15,17 connect to Switch pin 2 for ground.

I am going over to take a look at the boat this morning with the mechanic to understand better what is happening.

Pretty close... correction - EIM pin 5 to Switch pin 6 (all illustrated on page 19 at plug 2)

So the thing to measure at Plug 2... +5 VDC (P2-1) and +12 VDC (P2-6) to ground (P2-2)

 

[beernutz]

Does the main feed (+12v) wire behind the dash have good voltage?

Yes both the main feed wire carrying 12v and the wire on pin 1 which carries 5v have good voltage.

 

[beernutz]

Pretty close... correction - EIM pin 5 to Switch pin 6 (all illustrated on page 19 at plug 2)

So the thing to measure at Plug 2... +5 VDC (P2-1) and +12 VDC (P2-6) to ground (P2-2)

Oops, yes thanks for the correction, it is EIM pin 5 to S pin 6 with 12v+.

I just got back from seeing the mechanic and he has tested all the circuits for shorts without success so I told him just to go ahead and hook everything back up including the new switch pad and see what happens as he has spent many hours already troubleshooting. If it fries the new switch pad I will haul the boat back to the MarineMax in Pensacola as they probably have more experience dealing with this type problem. It is an hour+ drive each way but I think they'll have the best shot at finding and fixing the issue.

UPDATE: I just got a call after the mechanic reconnected all the components and unfortunately the new electronic switch pad doesn't work. So I am back to square one.