175 - Voltage on stop circuit

[night34606]

I have a SportJet 175xr2 with dual switch boxes and 6 coils. I found that I had a bad switch box and got 2 new ones. While hooking up I checked that there was voltage on the stop circuit (3 DC volts). I had the key switch and harness done last year so I am doubting it went bad more so something might be hooked up wrong. Any ideas on where to start looking?

 

[night34606]

Re: 175 - Voltage on stop circuit

As an update. I disconnected the stop switch from the harness. The harness end has no voltage. The end coming from the ecu has voltage - 3 DC volts. It makes no sense. Where is the current even coming from?

 

[CharlieB]

Re: 175 - Voltage on stop circuit

ECU?

The switchboxes should NOT be connected to the ECU.

The switchboxes have a Black wire with a thin Yellow trace used as the 'Ground-to-kill'. This wire should be dead when the motor is NOT turning as the ignition system is 'stator-driven', that is there is NO voltage within the system until the rotation of the flywheel magnets create the voltage in the stator.

If your system still has a third black box tied into the switchboxes Bias wire, it is highly recommended to totally remove that Idle Stabilizer Module as they have a nasty habit of going bad, changing the ignition timing and destroying motors.

 

[night34606]

Re: 175 - Voltage on stop circuit

OK So the key switch is hooked to the harness. Then the harness has a black\yellow lead - that black\yellow lead should wire directly to the switch boxes if I understand you correctly?

The ECU does indeed have a black \ yellow wire coming out it. I do not have a third box tied into the switch boxes. Only thing I have is the ECU, a single rectifier (i was surprised at only 1 from the diagrams I have seen - has 2 yellows, 2 reds and a tach wire) the 2 switch boxes and then 6 coils.

 

[night34606]

Re: 175 - Voltage on stop circuit

Ah I found the difference. The sportjet wiring is a bit different than the outboard but not by much. Looks like a bunch of sensors added to the thing and then the bias circuit and the stop circuit loop through the tks ecm what I refered to as the ecu. Now reality any reason I should not just wire the bias circuit and stop like the outboard? If I switched to premix instead of oil injected I would almost think it made sense to wire up everything like the outboard and eliminate the tks ecm as it does practically nothing except shut the boat down or alarm when things are low which I would be removing the need for the alarm \ warning if I premix, have a temp gauge and the enrichment solenoid does not do much IMO

http://motorka.org/doc/mercury/service_manual/jet/SJ175XR2_852396r1/2a.pdf - Review wiring diagram on 2a-16

vs

http://www.maxrules.com/oldmercs/Wiring/1966ona/53.jpg