WayneinMaine

The AC was removed long before I got it, there is no Tach. I will look into the CPS but wondering if it's simpler to just do the pressure switch and bypass the PCM problem altogether. Is there anything else it runs?

Joey-D

Just bought a 1992 D350 that is jumping in and out of overdrive. Without going too far into it, the VSS is new and speedo works well. TPS is shot. Minimum voltage and range out of spec. Also the Crank Positioning Sensor is disconnected. The previous owners have installed an external voltage regulator. So this means my ECM is bypassed. I presume but would like to verify that the POT mod is out of the question for my truck. My only option would be a manual switch to ground the overdrive solenoid to get a good working overdrive without correcting the years of adaptations and replacing my bad crank sensor, presumably bad ECM, and hacked up wiring harness.

brobrad

That would be correct. You can also use pressure switches in the test ports to lock up and for OD. You need adjustable switches where you can find tune it.

Rogan

I realize this is in the 1st Gen section, and mine is a 2G, but I think it's relevant.


So I did the TPS pot mod as a test for some of my trans problems. One of the many problems was that the OD engaged way too early.

so I bought the 271-1714 potentiometer and wired it up. worked like a champ, and was selectable for OD engagement, as expected.. Maiden roadtrip: 55 miles. About 40 miles into the trip, 65mph (pot set for OD engagement 40mph, disengage at 30-ish), all of a sudden, It pops out of OD and my 4.10 run the rpms up to about 2700! wow!

I pulled over, checked everything. All looked fine. Re-fired the truck and continued on, and it worked fine the last 15 or so miles.


On the way back, about the same time length/distance, it did it again. This time, I just shifted to neutral (while still at speed), cycled the ignition, re-fired it, put it in D, and away I went, good as new..

...for about 5 minutes, then it did it again. Repeated process, and another few minutes, it did it again. This time, I just pulled over, disconnected the pot, and re-connected the TPS and finished the trip home.

No idea why it's doing this on extended runs. Short, in-town runs, it's fine.

This is on a '97 3500 DRW.
no codes when it occurs

j_martin

Were you running on cruise control? My guess is the PCM noticed that cruise adjustments didn't move the throttle, and disabled all. Combination of safety factor and sophomoric programming. Surprised it didn't throw a code.

simplysmn

Also have a question on this .When you do the Pot Mod can you remove the TPS from the top of pump or do you have to leave it in place ?that's next step in the list of mod's

Rogan

No sir. My cc doesn't work; it never has worked since I got the truck.

Sent from my SPH-L710 using Tapatalk 2

infidel

brobrad

Sent you a PM.

marder

nyone know if this will work on a 3rd gen 48re? Im having problems with TC kicking out when i get on the go pedal.

NJTman

Decided to replace my potentiometer as a first step in my fixing 4th gear. I never liked the original placement, so good excuse for swapping all new.


Part 1 is attach harness to pot.

NJTman

Received my wire ends today. I need 3 pieces. Had to buy 200.

If anyone ever needs any, PM me, and I'll send you a few for doing this. I have a stamp and an envelope. All I need is your address.

Will continue the install in the next post.