82 Series Charging Circuit
 

Was working on a 782 the other day for a no start issue. Turns out to be multiple problems with the electrical.

One thing I noticed, and it drew my attention, was the two terminal Delphi connector from the KT-17 to the tractor wiring harness. This connector has (a) the power to the Ignition Coil, and (b) the power (12VDC B+) voltage from V/R back to the battery. The connector was discolored, burnt and in terrible shape. What drew my attention was, the wires from the Engine side of the connector seemed to be larger in diameter than the wires from the tractor side. Specifically, the 12V B+ (center terminal) of the V/R. Tore out with wires, the connector and the V/R. Upon closer inspection, the wires from the engine side were a 14GA wire for the 12V B+, and a 16GA for the Ignition Coil. The wires gauge on the tractor side were both 16GA wires. Hmmmm I know the Kohler charging system is a 15 Amp rating, thus this would require a 14GA wire, of which Kohler provided. That 14GA now feeds a 16GA wire which will handle 10 Amps. I looked at and studied the wiring diagram, and IH did install a 10 Amp fuse in this circuit. Thus the 16GA wire is properly protected. So which begs the question, does our Cub Cadets have a 15A charging circuit or a 10A??? :bigthink:

See attached image for better clarification.

The factory brochures called out the 15A figure, even though the 16GA wire on a 12VDC system is truly at it's industry standard safe limit at 13A. The 10A main slow blow fuse aids in protecting the harness from a total meltdown.

Since the harness is approaching it's maximum current limits, this might be one reason I find tons of melted plugs, and overheated connectors on these older tractors. You get a small amount of resistance caused by loose or corroded connections, then it turns into heat.

The ammeter on these is rated at 20 Amps. On a few of these tractors I've owned or worked on with a somewhat discharged battery, that ammeter's needle is almost to the second hash mark at full engine speed.

Attached is a pic of the replacement current MTD issue 925-3141 ammeter. The original ammeter does not have numerical graduations.