ariens no power

[ILENGINE]

Engineers for mechanical equipment and the automotive industry have changed their traditional electrical circuit game in recent years. Now it is not unusual to find fuses and relays in the negative circuit of many.

I recently got called to troubleshoot a Massey Ferguson farm tractor. The initial shop tech had a bad habit of throwing parts at problems with no actual diagnostics.

The problem turned out to be a 5A fuse for a main power relay ground. The other problem was it took the shop manager 3 weeks to call me after the situation got desperate and the farmer was screaming at him.

Most people never think to switch their simple test light lead over to battery positive post to verify the circuit negative side.

Most of the older techs grew up on positive side fused/positive side control. But with the integration of electronics and EFI into mower systems, there is getting to be a lot of positive side fused with ground side switched/ground side controlled systems.

Older techs grew up on points and condensor systems for spark. When the points open, or breaks the ground, you get spark. Now those "points" control the spark and timing, fuel injectors, throttle body, fuel pump, and in some cases the PTO.

 

[duke427]

have an ariens ikon 52 model 915223 has no power at key switch, traced all the wiring in according to wiring drawing found no problems, except at the area with fuses. continuity check was good from solenoid to 30 amp fuse, but from there to ignition switch there was nothing. replaced the brake switch no change. the crazy thing the wiring drawing shows a red wire going into and out the 30 amp fuse but this unit has red on one side and purple on the other side, the wiring drawing shows red should be in and out of 30 amp fuse. the 15 amp fuse has red wire going into fuse and purple coming out the drawing shows that purple should be in and out of 15 amp fuse. owner says was running and just stopped and will not start. mower will turn over when solenoid is jumped cross the poles. the owner did some electrical work on mower was told replaced key switch, but not sure if that was all that was done, is there a chance that someone changed the position of the red and purple wires going into the fuse panel delta executor roblox. any suggestion would be great
thank you
AC

Is there a chance that someone changed the position of the red?

 

[GearHead36]

Engineers for mechanical equipment and the automotive industry have changed their traditional electrical circuit game in recent years. Now it is not unusual to find fuses and relays in the negative circuit of many.

I've been an electrical engineer for 43 yrs, and this sounds insane to me. All my career, I've never seen switched grounds. Ground is ground. Sometimes there are separate signal and power grounds, but they get connected at a single point without using a switch. I would need the design engineer to sit down with me, and explain why this makes sense.

 

[Auto Doc's]

Hello G.,

A couple of years ago I was asked to troubleshoot a Massey Ferguson farm tractor for a crank-no start problem. The regular shop techs were baffled because they had tested all of the fuses (while the key was turned on) and dismissed any fuses that would not light the test light.

Once I studied the wiring diagram, I noticed there was a 5 Amp fuse for a main controller power relay ground indicated on the diagram. This baffled me at first, but I tested the fuse with an Ohm meter and found it was open circuit.

I replaced the fuse and the tractor immediately started up when cranked. The shop foreman was happy, but confused how a 5 Amp fuse could illude them for a few weeks before I was called in.

In the past, I have also worked on large hauling tractor trucks and many of them have fuses for the relay ground circuits, so a logic probe has to be used when testing the fuses.

I have never talked to an electrical design engineer to get their reasoning for this approach, but I am finding that I have had to change my "old school" testing approach.

As with any machine that has electrical circuits the ground is commonly the most overlooked side of a circuit. I think many people just do not understand how a circuit is supposed to have a complete path.

This may help:

Why is a ground circuit fuse used on a main power relay in a tractor? - Bing

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