electrical engine swap kohler cv 491 for kohler kt 715

brucew6char · Jan 14, 2022

i'm in the process of doing an engine swap on a 2005 or so l110 with a kohler cv491 1 cylinder with a kohler kt715 2 cylinder. got the engine mounted and fit under the hood, new throttle cable and remounted the muffler due to longer exhaust pipes. mostly done, now trying to figure out the engine electrical connector. i can plug in the connector plug. have both engines service manuals but the electrical diagram is not very helpful. just tells me the color of the wires but not where they go to or what they do.

turning the key on makes a slight click on the engine but does not crank. on the mower side i guess i can use a multimeter on some of the connectors and see which ones are ground or battery by the key position. not sure what i would be able to do on the kohler kt715 side of the connector. Anyone know where i can get a better wiring diagram?

RandyT · Jan 14, 2022

From the 6 pin connector on the engine Red is the wire to the fuel solenoid on the carb, Violet/purple connects to the voltage regulator, white is the kill wire for the ignition modules not to be confused with the two wires that also connect on each side of the purple wire on the voltage regulator. Blue would go to starter solenoid if equipped with the solenoid shift starter. And green would go to a oil pressure switch which may not be equipped

brucew6char · Jan 15, 2022

Thanks Randy, that helps some. But the wires on my connectors are different colors.

on the the mower i have 3 white, 1 red. the 491 doesn't have a fuel solenoid and the service manual says it has a 3 amp unregulated charging circuit. so i'll use a multimeter to determine which of the 3 whites is a kill, find which one goes to the starter solenoid and which one is a hot when switch is on to allow charging. and that leaves 1 extra unidentified wire. I still have the cv 491 around so i can look at the connector on the engine for additional clues.

on the kt 715, i have 1 red, 1 white, 1 green, 2 orange, 1 purple. one of oranges is spliced with the purple where it enters the engine side connector. the service manual indicates the red goes to the fuel solenoid. i'll assume the white is for kill and can test it if i get the engine running. the green is for an option i don't have. the orange splice to purple/violet should connect an ignition hot on the mower side to allow for charging. The service manual does indicate that a orange is spliced to a purple/violet and is used for charging.

still pretty confusing but if i can correctly pair up a few of the wires, it will narrow down my alternatives. i think i need a (1) kill connection, (2) an ignition hot for charging, (3) an ignition hot maybe hot start for the fuel solenoid, (4) a start hot for the starter solenoid. the green i'll ignore.

RandyT · Jan 15, 2022

I think one of the main sticking points is the CV491 doesn't have a fuel solenoid, which may also mean that the mower isn't wired to supply power to a fuel solenoid. I suspect that the red on the mower side was connected to the charging system black wire on the on CV491 which would now need to be connected to the purple wire. Double check that to make sure. Just make sure that you don't cross the white wire on the new engine side with battery power or you will be replacing the ignition modules on your new engine.

Also something else to watch in cases when swapping from an engine without fuel solenoid to an engine with fuel solenoid the key switch may not be internally wired to supply power to the fuel solenoid in both the run and start positions.

You will need constant power both in start and run for the red wire on the engine side. The white wire to kill the engine and the purple wire for charging, and in your case going from a 3 amp unregulated to a 15 amp regulated I would connect the purple wire either directly to the hot side of the starter solenoid or the B+ on the battery. The regulator has internal diodes so won't discharge the battery.

brucew6char · Jan 15, 2022

Thanks again for your response. I got out the old cv 491 engine which still had the plug connected to it. the service manual for the cv 491 had a better wiring diagram. so on the mower side of the plug, i think i'm able to identify from the engine wiring diagram the white kill lead pin, the black always hot charging pin, and the red hot pin when the key is on which goes to the spark advance module and fuel solenoid. confirmed this with a multi meter measuring voltage and ground based on the key position.

the starting solenoid is on the mower, not the engine so the wiring doesn't go through the engine connector plug. the key switch has 4 positions - off, on with lights, on without lights, start. i figured out why the engine wasn't cranking, idiot move on my part. i released the brake to lift the engine on. normally, when starting i'm sitting on the mower but with it on blocks, i didn't climb on. so the brake cut off wouldn't allow the engine to crank

i then put the mower plug into the kt 715. with the brake on, the engine cranks. turning the key to the first on positions causes the fuel solenoid to click. ran out of time to cross reference the rest of the connections from the mower to the kt 715 . wouldn't have time to do this until monday. but now knowing what the mower side pin connections do, think i can figure this out,

brucew6char · Jan 18, 2022

Today I got the wiring issues resolved. Here's what I did to accomplish this. I first tested the L110 plug for either 12 volts or ground in each of the key positions for each terminal in the engine connector plug.

I found 1 terminal with a red/black as always 12 volts. This is the charging connector.

The connector with the white terminal was the ignition kill and went to ground only with the key in the off position.

After looking a the connector wires more closely with a strong light and reading glasses, I determined that one connector was yellow, very faded, and not what i originally thought was white. This connector had 12 volts in the key position(2) on w/lights and key post ion(3) on wo/lights. The yellow powers the ignition module and fuel solenoid.

I stumbled around on the internet and eventually found the deere technical manual (TM2026) on the deere web site ($25) and got the downloadable pdf with a decent wiring diagram. This confirmed the wiring colors. I've attached the two pages of this wiring diagram.

the remaining connector was yellow/white, again very faded. This receives power from the red/black terminal connector on the engine voltage regulator and goes back to the key switch. From there it connects to the starter solenoid, mounted on the tractor, not the engine. Not sure why the power didn't come directly from the fuse mounted on the tractor but that's the way it is

I checked this against the wiring diagram for the original kohler cv 491 from the service manual. Kohler provides free downloadable service manuals for both the cv 491 and kt715. Then I confirmed that the plug on the deere would properly connect to the kt 715 using the wiring diagram from the kt715 service manual.

From the deere plug to the kt715

red/black to the purple – charging
white to white – ignition kill
yellow to red – ignition module and fuel solenoid
yellow/white to orange – power back to key switch for starting