Cub Cadet RMC Module what does it do when

DonCookJuly 1, 2014

Hello to all,

Is a Cub Cadet able to cut grass with the RMC removed?

I have read that the RMC Module can be removed and the Cub Cadet will be able to start with if the seat is occupied, the brake is depressed and the PTO/cutting deck switch is in the off position. I have been working through a problem with the mower not starting and have conducted electrical checks that have led me to replaced the key switch, the PTO switch, and the brake switch. My latest discovery was that the RMC Module was very warm after about two minutes of electrical checks. I removed the RMC Module and the mower will know start but the PTO/cutting deck will not function..

I am looking for information on the RMC Module and Its function in the engine starting and cutter deck operation.

Thanks for any help anyone can give.


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Well, you for sure have to be using a DVOM to test. No testy lighty. Are you saying that you crank, but don't have spark? Or do you have spark- but fuel isn't getting through? Or not cranking? Did they happen to put a model number on this unit?

    Bookmark   July 2, 2014 at 12:15AM
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OP - as you are requesting information that will assist you in defeating safety devices on your unit, intended or not.
IMHO, it is not advisable for us to discuss such on a public forum such as this. Should your machine later be involved in an injury accident, legal implications could be significant.

    Bookmark   July 2, 2014 at 1:29AM
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Thanks for the replies.

tomplum and rcbe, The lawn tractor is a Cub Cadet Model 1525. I have been using a Sperry model DSA-500 to do the electrical checks. Using the definition of a DVOM that I looked up on Google the Sperry meter I have been using is a DVOM.

The starter will not crank unless I am setting on the seat, I have the brake pressed and the PTO switch is in the disengaged position and the RMC Module is removed.

The motor is getting spark for the spark plug and fuel flows
when the starter turns. I have jumped 12 volts to the solenoid input and the coil completes the connection to the starter. The three limit switch safety devises (seat, brake and PTO) work correctly. And, when the RMC is removed the starter kicks in and the engine runs. When the RMC is left in the system the solenoid does not get enough voltage to allow the coil to function.

I have downloaded the Service Manual for the 1000/1500 Series Riding Tractors. On page 72 the maual says " The starter safety circuir has no connection to the RMC Module." The next paragraph says, " the safety circuits that are capable of turning-off the engine work through the RMC module."

The module 1525 does not have the RMC display on the dash of the tractor that is discribed and pictured in the remainder of the manual.

On page 75 the manual says, "When the RMC is disarmed , the tractor will operate as MTD tractors have historically operated:...." This statement on page 75 is why I have asked if the mower is really capable of cutting grass with the RMC removed. I do not understand what the RMC does that the seat, PTO and brake limit switches can not do.

I am not trying to wire around an safety device. I had a friend who wired around the seat switch and the mower flipped over and he was laying under the mower with the blade turning above him. HIs back was cut in several places by the blades. It took several months for him to recover. I do not want to place myself and my family members in an unsafe condition.

I am just trying to understand the RMC's function. I do not understand why the RMC appears to be dropping the voltage that the solenoid needs. And, why would the RMC be getting very warm when the key is turned on? Any insight would be appreciated.

Thanks again for reading and replying.


    Bookmark   July 2, 2014 at 11:34PM
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What are you referring to as the RMC module? Care to post a pic or part number? The ignition switch snaps into the RMC module if it has one. At least from what I have seen. Normally you don't have to be on the seat to crank as long as your PTO and brake switches are set.

    Bookmark   July 3, 2014 at 1:03AM
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tomplum, Thanks again for your reply. The RMC Module replacement part's package calls it a relay. I have attached two pictures. One shows the location of the part. The other picture shows the original part and the replacement that I was given by the dealer in St. Louis. I installed the replacement relay/RMC module and the mower started up but acted like the battery was low and the motor turned over very slowly. The PTO (mower blades) came on and we were able to mow the yard. When My wife shut the mower off, the mower would not start up again. I have not had time to investigate. I fear that the new relay/RMC Module may be burnt out. I will send another update later in the week. Again, thank you for your reply. Oh well, I can not get the second picture uploaded and it has been a long day.


    Bookmark   July 7, 2014 at 11:56PM
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tomplum and others,

Attached is the photo of the original and replacement relay/RMC for my Cub Cadet 1525.

Reference my post on 7/7/14, any thoughts as to what to check now would be appreciated.



    Bookmark   July 8, 2014 at 7:40AM
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That looks like a "generic" Bosch Relay.
Are the pins marked 85, 86, 87, 87A & 30?
IF so, Google Bosch Relay and you can see how it operates.

Since you have the schematic, could you scan that page and post it. (or provide a link to the manual)

    Bookmark   July 8, 2014 at 10:25AM
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These are different than the normal Bosch relay. The original number that you listed is for the entire ignition switch w/ the mow in reverse feature- which I don't know you have. The PTO relay that you show there may create the changes it does as the PTO swithc itself could be defective.

    Bookmark   July 8, 2014 at 11:17AM
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I have been told that the elctrical schematics for the cub cadet that I have are available on line at the every end of the Service Manual for the 1000 and 1500 series cub cadets. I have found the drawing but their resolution is very poor. So poor that I can not read the colors for the wires. There are three different electrical schematics. Page 84 does not show an RMC it shows a relay and a monitor, Page 85 has an RMC module and a relay. Page 86 has an RMC, a relay and a starter with the solenoid in the starter. Both P85 and 86 show a set of wires going to the position of the monitor shown on page 84 but noi mention of a monitor. I am know thinking that the item I thought was the RMC module and marked as being the RMC in the photo I sent earlier is in fact the relay. I do not think my series 1525 has an RMC on it.

I need to figure out how to check the relay and the wires coming to it to determine why the relay was getting out; why the mower will start with the relay pulled out; why the mower will not turn the PTO on when the rely is out.

tomplum and others, I appologize for taking so long to reply. I had back issues and had one of those microscope surgeries to ttim a bulging disk and remove spurs that had been pressing on the main nerve to my leg and feet. I am improving and waling ever well. I am still not allowed to bend over. So working on the lawn mower is still on hold.

I will send another note after the doctor clears me to crawl around on the ground again.

Thanks again for replying to my posts. I appreciate your input.


    Bookmark   July 28, 2014 at 10:17PM
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If it is just a Bosch Relay, Google Bosch Relay.
You can find all kinds of images, schematics, applications etc. etc.

    Bookmark   July 28, 2014 at 11:24PM
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I think that you may just want to try a new PTO switch. Its cheap and they don't last forever. You may want to research a little earlier in the manual to the troubleshooting rather than working away through your schematic. Do you not have the digital manual? Maybe the IPL has one for your tractor. Sometime when I can wrap my head around this, I'll let you know if I can help. We now think that this is a pre rmc model- correct?

    Bookmark   July 29, 2014 at 11:33PM
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