Engine/Transmission (1994 - 1998) A couple questions

[JStokes]

I have been posting quite a bit on the conversion board. I thought it would be good to get some feedback from some guys here that may not look there. I have a 47RH transmission behind my Cummins in my Suburban. I plan to manually engage OD and lockup. Will it hurt anything to do this with 12 volts, or do I need to drop it to 5 volts?



Also how do I purge my power steering? It has been puking when I shut it down. A bunch of foamy crap comes out and I can't get it to settle in and work. When I start it and fill it it works once I get the rpms up. Then all the fluid gets pushed back out on shutdown.

 

[Joe G.]

The OD and lockup are 12 volts. The way it's wired on the truck is that 12 volts is applied to the center pin in the connector. The two other pins are grounded for the desired function. The TPS on some of these trucks can be a major problem. You might want to read this thread about solving the TPS problems to get a better understanding of how OD and lockup work:

http://www.tdr1.com/forums/showthread.php?t=156901



Especially note what Howard Durand has to say. He has a 47RH.

 

[JStokes]

Great reading

I don't have a TPS and am drive by wire. I still have my GM computer in place and am using all my GM sending units on the Cummins. I don't know if the GM computer uses the sensor that my gauge uses but it seems that I could use radioshack parts in place of my GM TPS and trick my GM computer into controlling lockup and OD. It would take some one with a knowledge of both sytems to make it work. Who should I call?

 

[Joe G.]

I really don't know. The point of my response was to point out the ways these guys get around the TPS and other problems. However, if you can find someone who knows about how the computer works, you need a signal at about 50 MPH for OD. Another about 55 MPH or so for lockup. There are no sensors in the trans. It works off throttle position (which you can ignore) and MPH. To make it work as well as possible you also need a signal from the computer when the MPH slows to about 30 or so to control unlock and OD shift down. I think you might post on a forum that knows about your Chevy and ask them about the computer signals available.