Minn Kota Trolling Motor Faulty switch or coil?

[emrsw01]

Hi I have a Minn Kota Classic 40LBS Trolling Motor which has suddenly stopped working.
Battery ok and no response in either of 5 forward or 3 reverse speeds.
Assumed it was switch because if you shorted battery negative to Black motor wire the motor runs ok when in forward speed1-5 although at only one speed.
Also if you remove red,yellow and white wires and short to battery red it works at ok at different speeds. Again with black wires shorted out.
Purchased a new switch on Amazon in US ( I am in UK) and fitted it tonight with exact same symptoms.
Have i another faulty switch or an issue with the resistors down in the motor.
Motor has had low use in freshwater only. 3 years old.

 

[dingbat]

Hi I have a Minn Kota Classic 40LBS Trolling Motor which has suddenly stopped working.
Battery ok and no response in either of 5 forward or 3 reverse speeds.
Assumed it was switch because if you shorted battery negative to Black motor wire the motor runs ok when in forward speed1-5 although at only one speed.
Also if you remove red,yellow and white wires and short to battery red it works at ok at different speeds. Again with black wires shorted out.
Purchased a new switch on Amazon in US ( I am in UK) and fitted it tonight with exact same symptoms.
Have i another faulty switch or an issue with the resistors down in the motor.
Motor has had low use in freshwater only. 3 years old.

Looking at the schematic you have a switch and a “speed coil” in the circuit.

No functional description of the coil but it feeds what appears to be a simple speed selector switch.

Terminal C is the incoming power to the switch from the speed coil.

Check incoming power then check for continuity between terminal C and the various speed terminals to switch operation.

If it past these test you have a short in the motor connections or the windings of the motor

 

[emrsw01]

If i remove switch and connect black (-ve battery) to black motor and connect battery red+ve to red motor the motor runs. If i also connect red battery to either the white or yellow wires the motor runs but at a lower speed.
this surely proves that the motor and speed coils are ok and that swith is faulty

 

[dingbat]

If i remove switch and connect black (-ve battery) to black motor and connect battery red+ve to red motor the motor runs. If i also connect red battery to either the white or yellow wires the motor runs but at a lower speed.
this surely proves that the motor and speed coils are ok and that swith is faulty

Proves nothing…. Simple selector switch. The odds of all 5 contacts being bad is next to zero.

Did you check continuity between C terminal and the other 4 speed contacts?

If that checks there is nothing wrong with the switch.

What voltage do you get between C terminal and ground!

 

[emrsw01]

With a meter i can see no continuity between any of the contacts what ever position the rotary switch is in.
The contacts on mine are labelled Black. Batt -, Batt +, Red, white and yellow.
White and yellow are thinner wires which connect to the coil.
Red and Black go direct to motor and the other red and blacks go to battery terminals. Seeing 12v ok

 

[emrsw01]

Is the switch unit just a simple switch or are there any electronic components in there.
Checking switch again with meter i can see it connecting positive battery to positive motor and coil ( white and yellow) depending on switch position but the batt negative is going no where. If i manually short batt negative to black motor the engine runs with switch set in forward speed.

 

[dingbat]

Is the switch unit just a simple switch or are there any electronic components in there.
Checking switch again with meter i can see it connecting positive battery to positive motor and coil ( white and yellow) depending on switch position but the batt negative is going no where. If i manually short batt negative to black motor the engine runs with switch set in forward speed.

DC circuits are problematic to troubleshoot in that current takes the path of least resistance to ground, to the point that it will back feed to ground through other circuits.

You can not verify component integrity with the components still in the system and powered up. They must be isolated from the circuit and tested individually.

Running while touching ground simply tells you that particular winding is still intact inside the motor. Does nothing to isolate the problem within the circuit


If I’m looking at the correct schematic….

The speed switch is a simple contact switch. Connects incoming power to selected winding tap.

The motor has “X” fixed speeds done through multiple winding taps.

The “speed coil” listed in the parts list is drawn as a polarity reversing switch in the schematic. Reverses ground and power feed to “speed switch” to control motor direction.

I suspect, as I have all along, that the battery cables were hooked up backwards and took out the speed coil.

Pretty easy to verify if you tests the components individually as noted above

 

[emrsw01]

I followed this procedure for testing the switch. See https://www.google.com/url?sa=t&sou...-4ACegQIEhAG&usg=AOvVaw1JV0mzFtmDdcDhiwf3CK8x

I got same results as this so got to be switch.

 

[dingbat]

I followed this procedure for testing the switch. See https://www.google.com/url?sa=t&sou...-4ACegQIEhAG&usg=AOvVaw1JV0mzFtmDdcDhiwf3CK8x

I got same results as this so got to be switch.

Glad you sorted it out.

For giggles, check continuity through the switch from the power input terminal to the other terminals.

Has to be something on the input side of the switch. Only point of failure common between the speed outputs

 

[emrsw01]

Will only be convinced when i change the switch. Dont like coincidences.

 

[emrsw01]

Update.
Switch changed today and engine runs perfectly in all speeds.
Returned other switch and have already had refund.
Thanks for all help and suggestions.