Mtd rmc module

[38racing]

Anyone with experience on these reverse mowing options. Also known as OCR. I have one on 761 model. I have 2 different mtd manuals which are both inconsistent in what they say. I've followed the checklist testing all the leads to the module. Simplifying a bit but basically when the key is in the enable position a terminal of the module connected to a2 of keyswitch gets grounded via a2 to L as L is connected to ground. Then you press the triangle button to arm it and red led lights up and the ground route of the magneto to the reverse switch is opened. So here's my puzzle. I can arm it fine with the engine not running. Led stays on . moving park lever to park will turn it off as expected. Can release from park and re-arm. But if I start the engine it will not arm ( no led) when I press the triangle button. Or led might light up but only for a second or two. I just don't understand how a running engine changes anything. The module is fed battery power. To me only electrical difference when running is that there is power from charging system. I even disconnected the alternator feed but got same result. My tests on keyswitch show all connections expected.

[KE4AVB]

I can think of one possible difference. A running engine causes vibration. If you have a F56 (Packard) terminal with broken spring contact it could be losing contact. Personally I got only have one MTD with the module but the reverse kill is disconnected. No need for the feature here. Also that mower had the harness hack severely when I got it.

[38racing]

I can think of one possible difference. A running engine causes vibration. If you have a F56 (Packard) terminal with broken spring contact it could be losing contact. Personally I got only have one MTD with the module but the reverse kill is disconnected. No need for the feature here. Also that mower had the harness hack severely when I got it.

That was my thinking too. The model connector has the round pins. Problem is that it's not a case of jiggling the connections as this system has to be reset each time is goes off. I know module needs battery feed but not likely b terminal on keyswitch as antibackfire doesn't seem affected. I'll look closer at the a2 and L connectors. L connector ground has double lead for some reason. Its ground plus jumper to m ground so I expect it's not losing the ground.

[KE4AVB]

Still can be a lost of B+. I had a Craftsman mower last fall the fuel solenoid stayed engaged but I keep losing everytime went to crank the engine. Turned out to a bad battery cable terminal on the main positive battery cable. So you might need to monitor the B+ to module to see if it is dropping out. Same with the return ground circuit.

[38racing]

I'll check those. I checked some connections today but could find anything. I thought about vibration in the module assembly but I have it just dangling by the wires. Since it will go off if parking brake grounds a terminal in the module I took the connector off the switch. No change. So if it's the cause it has to be a fault to ground in the wire between the module connector and the parking lever connector. (Parking switch is totally separate from brake/clutch switch). So that's something I could test with engine and then on. I need to check out the b+ some more too. Manuals are contradictory as to source b+ and alternator feed. They re-routed those when they added an extra ground to the module, but mine has half the changes made. Hard to explain.

[38racing]

To give an idea of the challenge of the manuals. It refers to an after fire solenoid. A couple of paragraphs down it's now referred to as an afterlife solenoid. I kid you not. Might be same manual that says to engage parking brake to release tension on the varidrive rod when clearly the brake needs to be disengaged to relieve the tension.

[KE4AVB]

Considering some the crazy I have seen printed in manuals over the 40+ yrs I believe about anything. That about like a manual to lengthen a wooden board saw off a 1/4 inch.

[38racing]

So today. The connector for the module is 8 pin but only 7 have wires to them. Not in physical order , pins 1&2 are to ground. Pin 3 is to the magneto kill tab via the pto switch. Pin 4 is to the reverse switch. I'm assuming there is an internal switch between these latter 2 pins and turning on the module opens it, preventing the reverse switch from grounding the coil. That leaves the other pins. Pin 5 is to battery +. Pin 6 is a feed to the parking lever switch. If parking switch grounds this pin then module turns off. Pin 7 is to the keyswitch terminal A2 and is connected to keyswitch terminal L when key is arm position. L is always to ground.
So with engine off I test all pins (except 3&4). They read what they should with key in both running positions. Pins 1&2 have continuity to ground. Pin 5 has battery voltage. Pin 6 has no continuity to ground. Pin 7 has no continuity to ground in normal run and has continuity to ground in the 'arm' run. With engine off enabling and turning bypass on works. LED stays lit.
So I start the engine. I repeat tests on all the pins as above. Every reading is the same as when engine is not running. I kept each test connected for an extended time to see if any of them blipped. None did. I tried to turn module on. Either nothing or LED came on for a few seconds and then went off.
Unfortunately the starter solenoid is not easy to get to but I am going to try and splice into the wire going to the starter solenoid. I will arm and turn on the module. Then I will start it with a jumper to the solenoid so that the key stays in the 'arm' position. I'll see if the module now stays on with the engine running. Not sure what the result will mean though, either way.
My only other thought is that the 8 pin connector is an upgrade to the 7 pin. 8th pin is connected to ground

"When the OCR was first introduced for the 2005
model year, the module only had 7-pin in the harness connector.
In 2006, an eight pin was added to the module. The
eight pin is grounded and help protect the module from
system noise"
I'm wondering if the 7 pin would fail like mine is doing and hence the upgrade to 8 pin. Maybe this upgraded feature has also failed in mine?
$60 for a replacement is an expensive test.