I'm forced to drive my 94 dually right now. The problem is that the rh47 tranny will not shift into od or converter lockup until the engine is warmed up. the factory temp guage shows half way between 190 and the next mark below it before It will shift into OD. When it's below zero the engine will only get that warm at highway speed. If I go into town it cools down and won't warm up again for several miles of highway speed. That means the engine is running way faster that I like, just keeping up with traffic. I have cardboard right in front of the radiator (not on the grill) with only a 4 x10" hole in the center. Has anyone found this warm up to be caused a faulty therostat? Cooling at "sane" temps (like in late fall or summer) seems normal.
I found a reply by Wannadiesel where he explained that the temp sensor at the trans cooler line was just to lock out OD in the event of overheating and that the engine temp was used to determine upshift by temperature.
What I'd like to do is put a toggle switch on the trans to get to O.D. in cold weather. apparently I'm not using the right search words. I believe that I should ground the center pin on the tranny connecter to get O.D. Is that correct?
Thanks for all replies
Ray

 

Don't know if this will apply to yours but on the A518 there is a temp sensor that prevents the OD from kicking in till the trans hits a certain temp. doesn't get very cold here but even with a few degrees of frost only takes a couple blocks at 30MPH and OD kicks in.
Del

 

What you need to do is unplug the connector to the trans temp sensor and short the wires going away from the sensor together with a 1000 ohm resistor (25¢ Radio Shack)
Leave the sensor in place, disconnected.
This will trick the computer into thinking the tranny is at 70°.
I've been told by two diesel tranny experts that bypassing the low temp OD lockup won't hurt the tranny but you won't have the high temp idiot light and kick out of OD.
This is when you remove the stock sender and install an aftermarket gauge leaving the resistor in place.

Sensor location, driver's side

 

Thanks Infidel,
That's the info I needed. I'll do the resistor thing. I may remove it in the summer, who knows. The problem is only in temps around zero or below.
Isn't there a "sticky" for 2nd gens. the one for 1st gens is fantastic. info is easy to find and I'm sure it eliminates many of the same question, over and over. The WIKI for 2nd gens is of
no value.
Thanks again
Ray