3185 PTO Stops Working

seanmmcc · #1 07-28-2015, 10:13 PM

I have a 3185, B&S Vanguard, 1989 and haven't had great luck with it. Soon after purchase the shaft seal started leaking and had to be replaced. They also looked at the PTO that kept turning off, sometimes only a few seconds, sometimes it would run for 10 min before cutting off, other times the PTO wouldn't engage at all.

The issue seems to be electrical to me. I had the headlights on tonight and noticed they would flicker or shut off when the PTO stopped working. Sometimes pulling the PTO switch would make the lights come on but not the PTO itself. Sometimes the switch would do not thing.

I will dig up what has been replaced on the PTO to date, ex: switches but now think there is maybe a grounding, or intermittent power issue, or battery. I'm dont have alot of faith in the shop that has been working on my tractor right now so would really appreciate some input.

Any thoughts on how best to troubleshoot or where to look next would be a big help.

Thanks

Sean

DKCDKC · #2 07-28-2015, 11:28 PM

The 3185 was made in 1998 only and by all accounts is a solid machine. I'm investing a lot of time in repairing mine in hopes of long service. The PTO is engaged with a vacuum actuator at the right front of the engine. It is engaged, I believe, electrically with a switch on the dash. The coordinated electrical issues you note would indicate that the circuit has an intermittent issue. You can download wiring diagrams and try to puzzle out the issue. Or if you just want it to run, wire the PTO switch directly to the actuator to bypass the issue.

Of course, you may want to take some easy tests first and simply disconnect the plugs under the hood that power the headlights, and see if the issue is with the heatlights. There may be some other circuits you can disconnect to see if you can isolate the problem.

Good luck.

seanmmcc · #3 07-29-2015, 01:54 AM

Thanks for the input. Your right on 98 for the year, I transposed.

I tracked down the receipt for the work done in May and it was the PTO switch. I will start looking at the wiring.

Since the lights and the pto seems to have intermittent problems I am trying to consider what could affect them both like ground or something else?

Thanks

Sean

seanmmcc · #4 07-29-2015, 11:13 PM

I got a charger and charged the battery. Lights continued to not work. As I was following lines i moved the ignition switch plug wires and the lights came on. It is repeatable. Im going to start there...does the pto wiring tie in to the ignition at all?

I found a vaccum cable that seemed to run through the wiring harness from the pto vac. and it was just sitting near the fuse block. Should that be connected in to something?

Thanks

Sean

Oak · #5 07-30-2015, 06:18 AM

Yes. the pto is tied into the ignition switch. PM Roland and see if he can send you a schematic.

The early 3K machines ran a vent line from the pto actuator up near the fuse box. I'm thinking they did this for a breather tube for the actuator because the air is cleaner up there.

Here is what yours probably looks like.

DSC02954.jpg

seanmmcc · #6 07-30-2015, 02:04 PM

Yep that is similar to my line but it doesn't have a flare at the end. I was guessing it was a breather too.

I pulled the plug off the ignition and it has a half broken spade on the middle red wire connector. When I look at the ignition schematic it seems like this wire is involved in every ingniton state ex start run lights etc.

From the invoices the guy gave me I see the ignition switch was replaced last fall and pto switch about 2 months back. I bet he was chasing this same issue last year from the parts bought.

I am going to try to remove the little female spade wire from the plug and put a new one in. Does anyone know where it gets released from in the plug?

Thanks

Sean

ford4150 · #7 07-30-2015, 02:59 PM

There are many variations on how wires are captured in a connector. This will give you an idea of what you're dealing with. Generally there's a tab that must be compressed to release the wire.
https://www.youtube.com/watch?v=5xIEpYNTHFk

seanmmcc · #8 08-09-2015, 01:31 PM

I got the broken connector out and found a relay looking thing laying wedge in the ignition area, it must have fallen. I have been wondering why the fuse block looked like it was missing something.

Turns out it is the voltage regulator

I assume this could cause the PTO to randomly stop engaging? How did the mechanic not see this!

Thanks

Sean

Sam Mac · #9 08-09-2015, 01:39 PM

Doubt that it's the voltage regulator, the VR would be bolted to the engine. It's an aluminum box with 3 wires coming out of it and it's mounted just above the starter on a Vanguard.

Oak · #10 08-09-2015, 02:26 PM

Actually, that is the voltage sensor for the light in the dash.

There is a red and blue wire on the Evac-PTO solenoid. If the ignition switch is on, the red wire has 12 VDC. They break the blue wire (ground wire) through the PTO switch and also the reverse switch under the floor pan. Did you check the reverse switch? These tractors will not mow in reverse.
DSC02957.jpg