2010 Murray Electrical issue

[BGS Mex]

The red wire at the ign switch plug is the 12 volt feed not the white wire. Put a test light at back side of wire harness and turn key to is if switch is sending voltage out to starter solenoid. If power is coming out of switch test at starter solenoid the same way. If good there make sure ground wire to solenoid is on

Hi: This is a new switch. I have even tested (OK) the start solenoid, and tried another from an operational (Husqvarna) tractor. Yes; the red (letter B) on the switch is 12V feeding the switch. The White (S) is to the Start solenoid (Power) terminal. Both "main" grounds are fine. When I run 12 V direct from the battery to this white (solenoid) terminal the solenoid activates and powers the starter. When the ign. switch is turned to Start (S) there is 8.46 V there and the white solenoid conductor has 11.46 V (?). The battery reads 12.70 volts. I have an operational Husqvarna in the shop and I tried this Ignition Switch and it too tested 8.5 V at the "S" terminal. Both ignition switches work fine on the Husqvarna and test at 12.68 Volts. Both Solenoids work too!
Thank you: I am at a loss with this thing. I have been unable to find a correct Murray Electrical schematic and the one from the parts manual is pretty useless. I have been a licensed Canadian Mechanic for many decades and am embarrassed by this! I'm "retired" here in Mexico; I mostly do PWC's, outboards (Yamaha) and light construction equipment; there aren't many tractors sold here.

 

[Auto Doc's]

Hi BGS mex,

For true load testing, rig an old round incandescent head lamp and use it for load testing the wires.

Ohm testing can fool you into thinking a wire is good even if it only has 1 strand left, but it cannot carry the needed Amperage. A small test light has almost no load.

Another method is to connect your meter while set to "V" to each end of a wire and see if it read voltage when you activate a circuit. If it reads voltage there is a problem with a connection or the wire

I did not see your battery ground cable in the picture. Check where it is bolted to the chassis to make sure it is clean and tight. I've seen a lot of bad chassis grounds on riders.

Last but not least, check the fuse holder for loose pin fit to the fuse or if they have been heated up a lot.

I always like to say: "The smaller the machine, the bigger the problem can be to find".

Short story:

I had a Husqvarna 20YTH46 rider a while back that had me stumped for 2 days until I found that the ground for the start solenoid had broken at the crimp fitting for the headlamp harness connector. The 2 grounds were crimped together with the harness ground and then doubled back to the start solenoid. I had to open up the harness jacket tubing to finally find the solenoid ground wire loose down inside the tubing.

 

[BGS Mex]

Hi: This is a new switch. I have even tested (OK) the start solenoid, and tried another from an operational (Husqvarna) tractor. Yes; the red (letter B) on the switch is 12V feeding the switch. The White (S) is to the Start solenoid (Power) terminal. Both "main" grounds are fine. When I run 12 V direct from the battery to this white (solenoid) terminal the solenoid activates and powers the starter. When the ign. switch is turned to Start (S) there is 8.46 V there and the white solenoid conductor has 11.46 V (?). The battery reads 12.70 volts. I have an operational Husqvarna in the shop and I tried this Ignition Switch and it too tested 8.5 V at the "S" terminal. Both ignition switches work fine on the Husqvarna and test at 12.68 Volts. Both Solenoids work too!
Thank you: I am at a loss with this thing. I have been unable to find a correct Murray Electrical schematic and the one from the parts manual is pretty useless. I have been a licensed Canadian Mechanic for many decades and am embarrassed by this! I'm "retired" here in Mexico; I mostly do PWC's, outboards (Yamaha) and light construction equipment; there aren't many tractors sold here.

Thanx again: I have the Harness Jackets removed. This Voltage thing at the switch (S) has me stumped; especially as both the Murray start switch and Solenoid work fine on the Husqvarna. The solenoid "Ground" (black wire) is alone. I will check where the headlight ground wire terminates. As it isn't attached I didn't think it would affect anything.

 

[BGS Mex]

Hi BGS mex,

For true load testing, rig an old round incandescent head lamp and use it for load testing the wires.

Ohm testing can fool you into thinking a wire is good even if it only has 1 strand left, but it cannot carry the needed Amperage. A small test light has almost no load.

Another method is to connect your meter while set to "V" to each end of a wire and see if it read voltage when you activate a circuit. If it reads voltage there is a problem with a connection or the wire

I did not see your battery ground cable in the picture. Check where it is bolted to the chassis to make sure it is clean and tight. I've seen a lot of bad chassis grounds on riders.

Last but not least, check the fuse holder for loose pin fit to the fuse or if they have been heated up a lot.

I always like to say: "The smaller the machine, the bigger the problem can be to find".

Short story:

I had a Husqvarna 20YTH46 rider a while back that had me stumped for 2 days until I found that the ground for the start solenoid had broken at the crimp fitting for the headlamp harness connector. The 2 grounds were crimped together with the harness ground and then doubled back to the start solenoid. I had to open up the harness jacket tubing to finally find the solenoid ground wire loose down inside the tubing.

Thank you: The battery in the Murray is under the seat with the negative attached to the upright part of the frame there. I have also tried connecting a ground wire directly to the solenoid with no effect. The ground to the ignition switch is fed from the "Cowl Harness" and attached to the frame there. amperage and ground are among the thoughts that I have had. I just can't get a handle on why there is 11.81 volts on the white wire at the solenoid, and 8.50 at the ignition switch "S" terminal with the wire connected to it.. This makes absolutely no sense to me. I have been spoiled with the quality of the Electrical schematics from YAMAHA I guess.

 

[BGS Mex]

You folks have given me a thought. Given the Murray switch/solenoid combination tests and works fine on the Husqvarna; It must be something in the Murray wiring (positive, and ground) to the switch. I am thinking that I will disconnect the switch from the harness and connect seperate positive (B), ground (M) and solenoid S(white) and see what affect it may have. At the least it might give yet another idea.

 

[Auto Doc's]

Here is a generic diagram that may help:

https://www.motoruf.com/bild2cache/zenbit_katbilder_murray824_gif-1800-1265.jpg

 

[BGS Mex]

Here is a generic diagram that may help:

https://www.motoruf.com/bild2cache/zenbit_katbilder_murray824_gif-1800-1265.jpg

Thanx: I already have it. What do you think of my latest idea?

 

[Auto Doc's]

Just be careful that you are running 12V power to the correct circuit, same with ground. An inline fuse on your test wires would be wise. As a precaution disconnect the 2-stator wire to avoid any possible accidental damage while testing.

I use a basic Power Probe circuit tester most of the time when doing tests like this, it has built in safety circuit breaker.

 

[Auto Doc's]

Thanx: I already have it. What do you think of my latest idea?

Is the diagram scrubcadet10 sent you correct for your machine?

 

[Telesis]

You mentioned the ground terminal on the switch was "M" and I'm pretty sure that's the kill circuit to the ignition. The "G" terminal is the ground. I would try a jumper between B and S right at the switch. It can be in the off position and it should still pull in the solenoid when you connect the jumper.

As was previously mentioned, put a decent load(I use and old headlight) in parallel with your meter leads when you are measuring those voltages. I'd be curious if you still have the goofy 8.5 at the switch and 11.8 at the solenoid. I'd really like you to try this and post your results!

Finally, and I apologize if you mentioned it(I can't check as this server will time out on me!), I would double check all grounding, i.e. battery to chassis, chassis to engine, solenoid to chassis, etc. I'd disassemble every one and clean up all the mating surfaces.

Good luck!