I found this information on another lawn site. I have had electrical problems all year with my Scag -SMWC-61-A. After replacing a relay, key switch, starter and solenoid, battery, replacing negative ground placement on motor, plus other non-electrical problems throughout the year, I have spent more time fixing , than mowing. After using it the last couple times this year, I had no problems. UNTIL, I am the farthest place away from my house on my property. I figured my no start problem had to be a safety switch issue, due to engine cutting off while attempting to get out of seat. Long story, longer, I researched the interlock module on this Scag, finding that they have had issues. I found and followed the advise of the post below , on running a "piggy back" wire from module connection ( Green/Black wire), to negative side of battery. Eureka!!! Issue solved. You can keep this piggy back and ignore all safety switches, or replace the module. $105.00 I wish I could give the writer of this post more kudo's, but whoever you are, THANK YOU! KG
I confirmed power from the key switch on the green wire to the relay switch, but I did not hear a click in the relay. I then bench tested the new relay switch and confirmed poles 85+86 clicks and confirmed that poles 87+87a connect (have continuity) on the click.
As I understand it, the interlock module only provides a ground if all the safety systems are compliant. I was absolutely sure that all my switches were good and in the safe position and then tested them again at the module plug. Everything checked out safe.
So, recognizing that I am getting no ground out of the interlock module to activate the relay, I pulled the green/black wire out of the module plug and ran a jumper to it to connect to the negative terminal on the battery. My goal was just to see if the relay would click when grounded. However, I found that once this relay has a ground, and it clicks, it completes the circuit via the green/white wire sending power to the starter and the engine immediately started up.
This all makes perfect sense now. The ground jumper serves as the replacement to the ground that is normally provided by the normally working interlock module when all systems are safe. So I have effectively bypassed the interlock module and I believe, confirmed that the interlock module is bad. Apparently, it is relatively easy to bypass the interlock module with one ground wire used to activate the relay switch that enables the green/white wire to send power to the starter when you turn the key to the the start position.
With my ground wire in place, the engine starts, runs strong and I mowed for 6 hours yesterday with no problems.
You mention there is more going on in that module than meets the eye and I would be curious to know what that is. I can say with it completely removed at this time, aside from the safety element, I have not noticed any issues. It starts, runs and charges nicely. But I would be interested in knowing if there are any other electrical or mechanical concerns I should be aware of.
Please let me know what you learn.
Thanks,
GW
I confirmed power from the key switch on the green wire to the relay switch, but I did not hear a click in the relay. I then bench tested the new relay switch and confirmed poles 85+86 clicks and confirmed that poles 87+87a connect (have continuity) on the click.
As I understand it, the interlock module only provides a ground if all the safety systems are compliant. I was absolutely sure that all my switches were good and in the safe position and then tested them again at the module plug. Everything checked out safe.
So, recognizing that I am getting no ground out of the interlock module to activate the relay, I pulled the green/black wire out of the module plug and ran a jumper to it to connect to the negative terminal on the battery. My goal was just to see if the relay would click when grounded. However, I found that once this relay has a ground, and it clicks, it completes the circuit via the green/white wire sending power to the starter and the engine immediately started up.
This all makes perfect sense now. The ground jumper serves as the replacement to the ground that is normally provided by the normally working interlock module when all systems are safe. So I have effectively bypassed the interlock module and I believe, confirmed that the interlock module is bad. Apparently, it is relatively easy to bypass the interlock module with one ground wire used to activate the relay switch that enables the green/white wire to send power to the starter when you turn the key to the the start position.
With my ground wire in place, the engine starts, runs strong and I mowed for 6 hours yesterday with no problems.
You mention there is more going on in that module than meets the eye and I would be curious to know what that is. I can say with it completely removed at this time, aside from the safety element, I have not noticed any issues. It starts, runs and charges nicely. But I would be interested in knowing if there are any other electrical or mechanical concerns I should be aware of.
Please let me know what you learn.
Thanks,
GW