99 RAM

I am having a problem with my 47RE transmission. Every time the fuel tank level drops to 1/4 full the transmission will not shift out of first. I have serviced the transmission and replaced the speed transmitter but did not correct the problem. However every time I raised the tank level above 1/4 the transmission will shift normally. This occurs weather the transmission is cold or warm.

nitrousn

There should be no relation between the two unless you are starving for fuel keeping the rpms to low to shift properly. What is your fuel pressure when it wont shift?

Mechanos

99 RAM

I do not have a fuel pressure gage but engine rpm will go up to red line so I do not think that is the problem.

AlpineRAM

I'd check the grounds of the PCM on the firewall and if not already done put a separate ground from one of the bolts holding the pcm to the battery negative pole. To me it sounds like a ground problem somewhere as if the PCM was searching it's ground whereever it can get it and with the resistor of the fuel gauge offering ground and less resistance when full-..... just a shot in the dark nevertheless, but in my experience cleaning contacts and providing good grounds was always an advantage.

HTH

AlpineRAM

99 RAM

Great call! I cleaned the ground strap connections to the PCM and for good measure ran a new one to the battery. I have ran the fuel gage below 1/4 and it has ran perfectly so far. I plan on continueing the test but thanks for the great advice.

AlpineRAM

Glad I could help!

If you experience lockup cycling in OD you should also take a look at the battery poles, the connections in the PDC and the grounds on the engine and body.

AlpineRAM

ib516

WOW!

Good call AlpineRam! You are the man.

phxakguy

I'm not crazy after all!!! Thank goodness someone else has had this same problem I do. Everyone I have asked about this looks at me like i'm crazy. Was it only the grounding problem? I was wondering if you have had the problem come back?

phxakguy

I going to need some more help with this problem. I have cleaned all the ground connections going to the pcm and battery. The original problem still remains..... Just to make sure that I cleaned the connections correctly....how are you supposed to clean them?
THANK YOU IN ADVANCE FOR THE HELP!!!!

AlpineRAM

I usually take a wire brush to the battery poles and the clamps, some emory cloth for the ring type contacts to the chassis and body, contact cleaner spray for the plug type connectors. There is a plug type connector for the ground on the pass. side battery that sometimes rots off internally. (I usually cut away a little bit of the insulation and look for corrosion of the copper cable- if it's black I swap it for a new one.)

HTH

AlpineRAM