Help identifying wiring issues
 

I started a new thread due to this no longer being an issue with the starter/solenoid on my 2155 that I originally posted in the Kohler engine sub.

I am intermittently (more often than not) losing voltage on the blue start wire on the solenoid when key is in the Start position. Sometimes it will read 7V and not start, and other times it will have the correct 12V and engage the starter to crank the engine.

If I disconnect the blue wire from the solenoid and check with a meter, it reads 12V every time I turn the key to Start. But once I plug it into the solenoid and check, that's where I'm seeing the voltage drop to 7V sometimes. I have already replaced the solenoid as well.

I tested the brake switch by releasing the brake and turning the key. I get nothing - no "click" signaling the starter Bendix engaging, no lights on dash. If I engage the PTO switch I get the same thing. So both safety switches seem to be working.

Where else could I check? What is causing a drop in voltage at the start pin of the solenoid? I know it has to be something on the ground plane of the start circuit, but I've looked over the wiring diagram and can't figure it out.

Also, if I jumper the hot wire from the battery post on the solenoid to the blue pin, it will start due it getting the 12V it needs. So I'm guessing the solenoid and starter are good...

I think you have a bad wire or connector between switch and the solenoid pin. With blue wire disconnected from solenoid, your meter reads 12v, but as soon as you connect you get 7v. I'm running on theory that you have good reading with wire disconnected because you have no load on it other than the meter. Did you try a temporary wire from brake switch to solenoid pin?

I was thinking if I jumper ground straight from the battery to the solenoid casing and it works, then I know I've got a flaky ground circuit. Which could be either the PTO or Brake switches (and wiring) if I'm reading the wiring diagram correctly.

I'm going to try messing around with this more on my next day off (if it's not raining).

This situation was addressed and answered in a previous thread.

Either you don't want to do this, or don't know how. I am curious know which.

:bigthink:

I agree with Billy-O: poor connection, high resistance, loose wire, what ever you want to call it, it shows up when you try to flow current through to your solenoid. Full voltage unloaded circuit, low voltage loaded is the classic symptom.

It may take some detective work to locate. It might be a switch, a connector, even in a wire itself.

I agree with the temporary wire to the solenoid. If that works, it is proved beyond doubt.

My opinion would be that the contacts inside your key switch that apply battery to the solenoid lug are possibly corroded or otherwise not making good contact.
You can be seeing 12 volts with no load (wire off the solenoid), but with the solenoid connected you will have current flow and bad contacts can represent a resistance to the current thus dropping your voltage.

I would remove the key switch and meter for good continuity between the bat and sol lugs while operating the switch. :TwoCents:

Ok, I got a chance to look at it some more today. I ran a ground wire directly from the battery to the solenoid casing but still same issue. So does that mean it's NOT a ground issue?

The key switch is brand new I replaced it as part of my troubleshooting previously. I would try to run a straight wire from the switch to the solenoid but it's a moulded connector on the switch I can't access the individual pins...

Brand new switch? or brand new correct switch??
How did the connections and female terminals look on the wires that plug onto that new switch look?
Bright and shiny or green and yucky?

If I'm looking at the correct drawing, the key switch for a 2155 should be p/n 925-3163.
You should see good continuity between the B and S lugs when the key is turned to the start position.

If I'm looking at the correct wire diagram for a 2155,
the blue wire for the solenoid joins up with red and orange wires in the engine connector.
The orange wire brings the voltage into the engine connector after it passes through the brake safety switch and the PTO switch.
The red wire feeds voltage to the fuel solenoid and the PTO.
I would pull the plug off of the fuel solenoid and the PTO and see if the voltage still drops at the starter solenoid when the key is operated.