For anyone who whishes to hardwire a custom decoder; I choose a TCSKAT26. Follow these instructions to install this decoder in such a way that in the future you can eaisly remove the powered KATO P42 trucks for repair, inspection, or replacement. First of all go to: http://www.katousa.com/HO/P42/maint/DCC-install.html Follow step 1 and omit the instructions written with bold letters. I did this project with only rail cutters for cutting wires, the small Phillips screwdriver, 30AWG, wire, soldering iron with solder, and single prong jumper wires, with male and female heads. Found here: http://www.ebay.com/itm/191221171555?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT You can use everything listed on step one on the KATO P42 decoder installation page or you can youse some its up to you. I only mentioned the tools that I used.
Proceed to step to step 2 on that page. After you are done reading step 2 move on to step three, and then step 4. Omit step 5, and jump to step 6. Use gray and orange wires. Connect black wire to gray and red wire to orange wire. You can do the opposite if you want. Stop at step 6. Turn over the model. Thread the longer wires that you soldered to the trucks through the openings as highlighted with the yellow arrows here. You don't have to drill the hole that is indicated but go ahead if you want. I did not.
Reattach the trucks to the chassis - when reattaching the trucks, the front truck is marked with an "F" on the underside and the rear with an "R", while the arrow molded on the underside should always point towards the nearest coupler and away from the fuel tank. You can do this if you want: Ensure the wires are seated correctly and will not interfere with the movement of the trucks, remove the gray frame half spacers from the top of the mechanism (photo #2) on the KATO P42 page, and feed the wires from the trucks between the frame halves and underneath where the gray clips are mounted, being sure to test the wiggle of the trucks to ensure that the wires or not being pulled so tightly as to restrict their movement.
Peel off 2 (orange and gray) jumper wire cables from the bundle, and cut the wires in half. Take the female end of the orange and gray wires and solder the truck wires to 2 female ends of the single prong jumper wires on the rear end of the P42. There will be 2 female ends of the jumper cables soldered onto the orange wire on the rear truck of the P42 and the same goes for the gray wire. You may want to cut the lenght of one set of the orange and gray jumper wires before you begin soldering meaning one long orange wire and one long orange wire the same goes gor the gray wire. You want two of them to be short so you connect those two to the orage and gray wires of the TCS KAT26 decoder.
Take a a TCS KAT26 decoder and solder 2 male ends of the orange and gray jumper wire cables to the orange and gray motor wires of the TCS KAT26 decoder. When you're done snap the KAT26 decoder's newly soldered male jumper wires, orange and gray, to the orange and gray female jumper wires that you soldered earlier at the rear of the P42. There will be one set of longer orange and gray female wires left at the rear truck of the p42. Solder a pair orange and gray male jumper wires to the front truck of the P42 and connect them to the longer set of orange and gray female jumper wires comming from the rear of the P42 truck.
Thats pretty much it youre done hardwiring the TCS KAT26 decoder to the KATO P42. It should look like this when you are done. Bellow the jumper wire connections are highlighted. You may use the illustration below as a reference to earlier steps in case of misunderstanding or messing up. You may use heat shrink tubing or electrical tape or paste to insulate the solder joints.
You may connect orange to orange and gray to gray, but depending of the polarity of the power comming from the motor output wires orange and gray wires from the TCS KAT26 decoder, you may have to unplug the orange and gray male female jumper wires that connects the front and rear trucks of the P42 that you soldered earlier and invert "swap them" meaning unplug orange to orange and gray to gray and plug orange to gray and gray to orange this should fix an issue in which the front and rear motors will spin in opposite directions when being run on DCC or tested with a 9v battery which will stall the train Lol.
From here on if tested, and the P42 runs fine changing directions on your DCC command station, you may make the wires look neat andput the shell back on, or install leds, which will not be covered here. Yo may hardwire a Loksound Soundtraxx or Digitrax sound decoder in addition to this installation. You may do it traditionally like being attached to the KAT TCS decoder in which it may never be removed once attached inless you unsolder, or you may wire the sound decoder using the method in this article in which the sound decoder may be removed seperatly in case of RMAing, inspection, etc... You may also use the 2 pin or 6 pin micro decoder connectors found on the Train Control Systems website or eBay. When installing a sound decoder.