Replacing the TPS with a potentiometer -A

[Paccool]

Here is an Email that a member sent me regarding unhooking the TPS and using a potentiometer in its place. It is a fairley straight forward prrocedure. Instead of a 10 turn pot, I used a one turn. I can set the pointer anywhere between the 9 oclock and 1 oclock locations. I crank the dial up when towing so it shifts a little later and turn it down for everyday driving so it shifts sooner.

Stan

Use a cable that is 18 gauge three wire and is shielded and suitable for outdoor use. The cable should have three wires colored red, black and white and has a bare wire wrapped with it and covered with some tin foil and PVC outer cover. Should be available through radio shack or electric wire
distributor. The bare wire is not used so cut it back.

The pot was a 5K ohm, ten turn, 1/2 watt, you can go to 1 watt but it will
just be a little heavier duty. (look at my comments above about a one turn pot - Stan ) You can mount the pot on the dash at a convienient location. It can be in a small project box, in the panel where the OD switch is located, in the message center area, etc. Look on the side if the pot and you will see a diagram and it shows the terminals, 1, 2 and 3. On the pot the two terminals closest together are 1 and 2 with 2 being the terminal closest to the knob end and 3 is the terminal located at the end of the pot and rotated down from the other two.

I used fully insulated connectors, male and female to do the hook up. I pigtailed the pot so if it ever goes out I could change it out easily. I used the following colors: Black to terminal 1, white to terminal 2 and red to terminal 3 on the pot.

I ran the cable up front and cut the connector to the TPS leaving enough
wire so I could re-hook TPS up again if I need to. The connectors have to be
opposite of the type you are using on the cable to reinstall the TPS if
needed.

I connected the black wire to the black wire, the white wire to the orange with dark blue stripe and the red to the violet with white strip.

Most pots are clockwise rotation meaning the more you turn the knob CW, the
higher the voltage. To set the voltage unhook the white wire in the new cable from the orange with dark blue stripe and hook red lead from VOM to the white wire connector and adjust the voltage you want. .7 volts is what I
set mine at.

One thing I want to remind you about, the tranny will not drop into passing
gear (out of overdrive) when you are really getting on it, you will have to
push the button to make it do that if you are in a hurry.

The controller is seeing a voltage that does not vary but the more or less
voltage you crank into the signal line (orange with dark-blue strip) will vary the shift point some what. The more fuel I give my truck the higher MPH it shifts into OD. Just depends how yours is set up. Normally with very light throttle it shifts into OD about 37 to 40 and allot of throttle about 50-55. It will shift quick, no hesitation. Be sure and fill the connectors with dielectric grease also.
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Stan

93 D250, PDR Twins HX35&HT3B, 60+# boost,PDR stage 2 head w/o-rings, PDR Cam, modified VE Pump, piston style lift pump, modified 5" intake w/AFE, ATS ported manifold,DTT 89% converter, 4" RIP exhaust, modified tranny, EGT/boost/tranny/tach gauges, TPS removed, a little chrome under the hood. Mag-Hitec tranny and diff. covers. Rear sway bar. Line-x bed liner, after market seats. Front end rebuilt with new springs - 2 " taller now. Single stage Water/Meth system installed. Oversized intercooler w/3" IC lines.

05 Chevy 2500 HD, Duramax W/Allison, 17" Hummer wheels w/285-70-17 BFG's, modified air box, ported turbo mouthpiece. Predator programmer.

[paul_the_welder]

Well I bought all the stuff and hooked it up, but I cant get it to work. The POT that I bought all the connectors are evenly spaced. So im kind of confused as to which wire goes where. In your instructions two of your connectors were closer to each other. Can I screw anything up hooking it up the wrong way? I hope not because I've tried several different ways.

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1993 ext cab 4x4 , auto tranny, marine +40hp injectors, holset 16mm housing turbo, pump turned up.

[paul_the_welder]

I got it to work

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1993 ext cab 4x4 , auto tranny, marine +40hp injectors, holset 16mm housing turbo, pump turned up.

[Paccool]

Paul, is it working OK? you should be able to set the shift point. You got a one turn put like I used and I like a lot. I felt the 10 turn would be too confusing to keep track of where you were at.

Stan

[paul_the_welder]

Yeah I got it working. I had to get to sleep since I wake up at 2:30am. I dident have time to mess with it to much , but it was shifting into overdrive fine. I set it about 1/2 turn and it was hitting overdrive about 40mph.


thanks! Paul

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1993 ext cab 4x4 , auto tranny, marine +40hp injectors, holset 16mm housing turbo, pump turned up.

[sdstriper]

Just wanted to comment on this sheathed wire recommended. I would ask for or have your autoparts etc order a "triplex jacketed cable or wire". This is three wires, coated same as you would use normally, but all three in a sheath or jacket. I recently had Napa order me 12 AWG triplex sheathed cable, 3 coated 12 gauge wires in a pvc cable sheath, so I know it is avail. I cannot remember what they called it but if you explain it to them, you'll get what you want. It ain't cheap, 3-4 bucks a foot. My concern is that bare wire in there not being used, something rubs raw with that combo recommended and now you got an added variable to trouble shoot, I hate electrical problems. Keep It Stupid Simple or KISS, triplex sheathed cable or jacketed cable, whatever, ask around until you get what you want. Eliminate the possibility of a problem right out of the box.

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1989 D250, Built 727HD, D70/3.07, BHAF & DIY cold air, gauges, 4" exhaust, Tuned VE

[paul_the_welder]

Thanks paccool for your help. my dealership wanted 320$ for a tps. I spent 11$ on the pot, wires and connectors at radioshack and it drives just like it did before, plus its adjustable. You helped me alot!

Paul

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1993 ext cab 4x4 , auto tranny, marine +40hp injectors, holset 16mm housing turbo, pump turned up.

[Greenleaf]

I purchased a potentiometer at Radio Shack for 2.80 and the knob (package of four) was a little over 3.00

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1990 D250/1992 D250 Modified by **Smokehouse Diesel** Ashland, OH

....therefore, my brothers, I want you to know that through Jesus the forgiveness of sins is proclaimed to you. Acts 13:38

[SSG. Diesel]

does any one have pics, or able to break it down into lamins terms.

my fathers truck has Issues with shifting into overdrive, its a 91.

im not even sure where the tps is located.

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2005,QC,Long Bed,Six Speed CUMMINS work truck package

[dave330r]

this problem is why i joined this forum, as soon as my wife gets home with the truck i am headed to radio shack

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'93 dodge cummins 4x4 auto w/od stock except straight piped this afternoon 4-1-07