rustydiesel

Well my TPS died a "short" death. Knowing that a pot would provide an adjustable, but fixed O/D shift point (i.e. not like the actual TPS which informs the logic of the PCM to shift at variable points) I thought what the heck, I'll cough up for an actual TPS. Well folks, here in sunny Ontario I got a quote from Chrysler Canada for $630!!!! That is no typo. Just for the sensor in a box! I grabbed a 5k-ohm linear pot from my wife's trade school kit, some scrap shielded signal wire and half an hour later I'm back on the road.

Of course it does not operate the same as a TPS, nor does it shift as the factory intended. I have my shift point set quite low...about 39mph, but if I am not on the ball and accelerate through that, it shifts into O/D rather harder than I would like. And, I am told that the O/D tailpiece on the a-518 is a bit of a weak point. Sure, you can set the shift point later, but it is still a single shift point.

Mind you, I am very happy for the fast and free fix, but I suspect I will wind up with Rampage1967's "3.0 liter V6 TPS" modification when I get the time. The other suggestion of using a pressure switch in the governor port on the tranny (without any other inputs) is also a single shift point and while elegant in its own right, is harder to adjust than the free, or almost free pot.

My 2 cents Canadian, which at present is worth 2.04374 cents U$

j_martin

Went around that bush a couple of times. First time around I decided to try to clean the original TPS. I used some automotive electrical cleaner and it didn't work well.

Last time around I noticed that when you look at the bottom of the TPS, there is a little hole where you can see the end of the spring. I forced a product called DeOxit (D series) through that hole, worked the sensor, shook it out, etc about 3 times.

Works perfect.

DeOxit can be bought a couple of places.
Fraction of an ounce at an exorbitant price at Rat Shack.
6 oz or so for about 20 bucks at a music/guitar store.

There's 2 types. One's for gold contacts. Trust me, there ain't much gold in these first gens.

NJTman

I bought mine on Amazon, and it's amazing on how well it works. I also bought their "protectant" as it leaves a nice coating on the metal afterwords to protect it from further deterioration.

Cleaned up my fuse panel like it was brand new.

BTW, I switched from the OE sensor to the POT from RS about 7-8 months ago. Flawless shifts since.

charger 69

Do you still have cruise control with the POT ?? as I need to do mine. Thanks.

rustydiesel

Sure you have cruise, and it will shift into o.d. at the same speed every time. What you do not have is the throttle position sensor which otherwise dials in your shift into o.d. based on your load or acceleration...i.e. how hard you are pushing it. So if you have a large load or are stepping on it...with the pot. controlling things you will be stressing the o.d. gear in my opinion. So in those conditions it would be better to turn off the o.d.

j_martin

Doesn't affect cruise control. If yer pulling heavy, you can always either change the pot setting, or manually hold off the OD shift.

I have found that the TPS is cleanable, and I like the automation.

E.Roy

Thanks for this tip Spitzair, I installed an old school Highbeam dimmer switch on the floor near my left foot. I think someone else in the thread also did this. I love it, because now OD is controlled by my brain (through my foot).

The 2-wire connector you need to ground is located on the driverside of the trans, connector points down into OD solenoid. There are two wires, the larger blue wire is power (~12v), the pink with green stripe is ground (check continuity with frame). Snip the pink ground 4" from the connector and crimp and wire the connector side of it, run it up to the driver footwell. The wire will be interupted by a switch that ungrounds the OD solenoid, disengaging OD.

It takes about 2 seconds for the shift to happen after you click the switch. I still need to add a light that comes on when the OD is engaged, because I loose track of where it is when in traffic.

Cougsfan

After fighting an intermittent faulty TPS for years, I finally installed the potentiometer. Had to read this thread several times to fully understand what to do. I used the nails for connector into the wiring harness as someone suggested. Did it in a couple hours , and it seems to work fine right off the get-go. Was actually easier to do than I expected. The hardest part was braiding some 18 gauge wire (Couldn't find any pre-braided). Had to enlist my wife to show me how to braid.

infidel

nomula

I know this is an old thread but hope some of you are still following it.

Ok, tried replacing TPS with a pot last night, but guess I guess I missed something. (or there is more wrong with the truck).

I used 20/3 thermostat wire (only thing at hardware store that might work). It is not stranded wire, but has 3 wires inside a sheath, and since solid wire, I figure will be fine if not bend back and forth, which is wont be. I unplugged the TSP and the wires fit right in the plug. I put the red one in middle so I would know for other end. Weaved it thru the firewall and up under the dash. Found a 6 hole plug off of a tore down dvd play and plugged right into my pot, skipping holes. So took the wires from those holes and attached to my 20/3 wire. Temp taped it to dash and took a drive.

When turned all the way one way, it dimmed lights, just off from that it light check engine light. Tried setting it both ways, and several areas in between. No OD; pulled over and switched so outside wires were opposite. Still no difference.

It is a linear pot, .5w? (listed as watts on ebay, but did they mean volts?), but 10k OHM.

Do I need some sort of resistor? or if some other part of truck is messed up it wont work? I read about resetting computer, should I do the neg disconnect, turn key to crank thing for this or am I in deeper doodoo?

Thanks

j_martin

TPS shouldn't affect the lights, but CPS would.

The normal pot is about 3K. 10 should work, but might be more susceptible to noise.

ValorSolo

Old post but great info. Now I have OD. Thanks to the OP.

I bought a pack of 6 pots for $6.99. Wired one up and installed it near the info center. OD works great now.

My tranny shifts so smooth that I can't really tell where to set shift points.
I'd like to add a LED that lights up when OD engages. Any ideas on doing this?
Just need the light until I get shift points marked, but I may keep it and install it above the switch.

Oh, btw these are 5k linear pots.

j_martin

Just wire it across the OD solenoid. You can use a lamp, or a resistor and an LED. (a 12v led would have the resistor built in) One wire to the solenoid, and one to any 12V would work.

ValorSolo

Thanks for the info. I ordered an LED indicator light that should be here in the next day or two. Your instructions sound simple enough. I should be able to follow that. I'll post back how it goes. Once again, thank you.