Cat 627B Scraper Transmission Issues

We have a Cat 627B scraper I have been working on. The tractor serial number is 15S983. The scraper serial number is wore off but we believe it is 38V00045. The issue is the tractor and scraper transmissions don't seem to be on the same page as far as shifting goes. The previous owner rewired the machine from the transmission neutral/run switch to the back transmission. The most extreme example of what we are dealing with is the tractor trans would be in reverse and the scraper would be in a forward gear. Lightly pressing each gas pedal verified this without causing any damage. I verified all the wiring was good from the tractor trans switch back to the scraper trans switch. I also changed the scraper trans switch but it didn't help. I'm going to verify that the trans neutral/run wiring that was ran is indeed good. Any help or troubleshooting guides would be greatly appreciated. Thanks

Not sure what I'm doing wrong but the email you just sent with the electrical schematics is telling me "Requested conversation could not be found".

I started tracing wires from the transmission neutral/run switch and found a faulty manual transmission switch on the tractor. I had the machine running and in neutral. Measured 24 volts at the neutral terminal but also 19 volts at the reverse terminal. Switched to "Run" and put it in 1st gear and had 24 volts at all the forward gear terminals. Should only have been power at the 1st gear terminal.

I am looking for a new transmission neutral/run switch with 3 pins on the back to match the current one. Need power in the center and then "Neutral" on one side and "Run" on the other. Tried through Cat and they got me a 2 pin switch and can't seem to find the correct one.

gary1975 said: I am looking for a new transmission neutral/run switch with 3 pins on the back to match the current one. Need power in the center and then "Neutral" on one side and "Run" on the other. Tried through Cat and they got me a 2 pin switch and can't seem to find the correct one. Click to expand... So that switch is on the front end.? Post a photo or two of it.

Yes in the cab. Here are some pictures. That is the switch Cat got me.

What Part Number is the switch in your photo.? 8D-2676 by any chance.?

It's 7N-8001

I make no guarantees but you could try 8D-2676. FYI that Part Number is used right the way through 15S-prefix production in the battery & cab wiring group.

And we have a winner. From an old schematic - 4D-1836.