Super Cool and CHEAP TPS fix! Dial-in your OD shift point!
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Joined: Nov 2008
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From: Lebanon Indiana
Has anyone experienced any troubles or any experience with the transmission temperature sensor? As i have come to understand, that many of these OD shifting problems may be caused by the TTS which measures cold ambiant air tempurature as well as overheating transmission temps. Both low and high temps prevent the trans from shifting into OD. I've been told by a transmission shop, that by us using a potentiometer as the tps, we're defeating the TTS circuit (which may be the root cause of the messed up OD shift patterns.)
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Joined: Dec 2010
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Give it a try Denis - you'll like it.
Just remember: The TPS is "upside down" in reference to the normal pot. The potentiometer you buy will increase when turned clockwise. The one on the truck does also, but it's flipped over. Disconnect the one on the truck, flip it over, and then wire the pot in the same configuration. Get it?
Then re-install the TPS, but just leave it disconnected. That way it's easy to switch back if you need to do so.
Just remember: The TPS is "upside down" in reference to the normal pot. The potentiometer you buy will increase when turned clockwise. The one on the truck does also, but it's flipped over. Disconnect the one on the truck, flip it over, and then wire the pot in the same configuration. Get it?
Then re-install the TPS, but just leave it disconnected. That way it's easy to switch back if you need to do so.
To set the pot to have OD kick in, do you need to use a voltmeter? Or do you guys just fiddle with it until OD kicks in where you want it?
Has anyone put together a "shopping list" for this mod? I'm terrible at electronics! From what I understand, I would need the following:
5000 ohm linear taper potentiometer
3 butt end connectors
10' braided 3 wire
Thanks for the help!
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So, I had more of a chance to test out the potentiometer mod today, and had problems. I'm hoping someone can confirm my two theories...
I took some pins from a PC plug and crimped (butt-end connectors) them to the ends of the wires running from the pot, and plugged it into the female TPS plug. My first theory is that the pins aren't quite long enough, so signal from the pot to the TPS plug is inconsistent. I'm assuming this would cause the OD to disengage intermittently, like it was before with the bad TPS. It's quite a bit better than it was, but OD is still kicking out. (I've switched the two outside wires back and forth a few times)
My second theory is that the second gen TPS is more influential than the first gen, meaning the potentiometer isn't doing what the TPS did previous???
I'm thinking it's a connection problem, anyone have some thoughts?
**Edit: after spending the day fiddling around with it, cutting and recrimping all the connections and using brass pins as the TPS plug, and heatshrinking everything, it is functioning as it did before, with the bad TPS. I know all of my connections are as good as they can get without sautering them. Am I missing something? the pot should just wire directly to the female TPS plug, right?
Thanks in advance diesel gurus!!
I took some pins from a PC plug and crimped (butt-end connectors) them to the ends of the wires running from the pot, and plugged it into the female TPS plug. My first theory is that the pins aren't quite long enough, so signal from the pot to the TPS plug is inconsistent. I'm assuming this would cause the OD to disengage intermittently, like it was before with the bad TPS. It's quite a bit better than it was, but OD is still kicking out. (I've switched the two outside wires back and forth a few times)
My second theory is that the second gen TPS is more influential than the first gen, meaning the potentiometer isn't doing what the TPS did previous???
I'm thinking it's a connection problem, anyone have some thoughts?
**Edit: after spending the day fiddling around with it, cutting and recrimping all the connections and using brass pins as the TPS plug, and heatshrinking everything, it is functioning as it did before, with the bad TPS. I know all of my connections are as good as they can get without sautering them. Am I missing something? the pot should just wire directly to the female TPS plug, right?
Thanks in advance diesel gurus!!
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Joined: Aug 2012
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From: Miami
I tried bypassing my dead TPS with a POT, I can’t get it to work. I’ve read this thread numerous times to see if I missed anything.
I have the correct POT.
I’m using 18 gauge wire.
The red wire is in the center, I’ve tried switching sides on the 2 outside wires.
The truck is not charging the battery; the speedo stays at zero and the OD button light remains off. The truck died on me when I was driving it last week. After going back the next day to pick it up, I installed a fully charged battery, it fired up and everything worked fine, I had OD, the battery was being charged, the speedo was working and the OD button light was on. Then after 5 minutes of driving I lost OD again, the speedo went flat, etc. etc.
I unscrewed the speedo cable at the tailshaft and taped the rounded off shaft and slid it back in, went for a test drive…no improvement.
I put the TPS back on…no improvement.
I stared into the engine bay for 15 minutes and whispered sweet nothings ...no improvement.
Next steps, remove the taped speedo sensor and replace with a new one. Check the voltage with the bad TPS on (will this really matter?).
Any recommendations?
I have the correct POT.
I’m using 18 gauge wire.
The red wire is in the center, I’ve tried switching sides on the 2 outside wires.
The truck is not charging the battery; the speedo stays at zero and the OD button light remains off. The truck died on me when I was driving it last week. After going back the next day to pick it up, I installed a fully charged battery, it fired up and everything worked fine, I had OD, the battery was being charged, the speedo was working and the OD button light was on. Then after 5 minutes of driving I lost OD again, the speedo went flat, etc. etc.
I unscrewed the speedo cable at the tailshaft and taped the rounded off shaft and slid it back in, went for a test drive…no improvement.
I put the TPS back on…no improvement.
I stared into the engine bay for 15 minutes and whispered sweet nothings ...no improvement.
Next steps, remove the taped speedo sensor and replace with a new one. Check the voltage with the bad TPS on (will this really matter?).
Any recommendations?
Yup.
There's ground screws on both fenders. Take off and sand to bare metal, including wire ends, spray with electrical spray (dont use silicon - it forms a barrier that significantly resists low volt/amp signals like with the pcm (see audi engineers comments below post).
Any splices? I had one. Turns out this was my culprit. Bypassed with new wire to clean fender contact/bolt and instruments popped back on...but not before spending bucks on a new Speed Sensor...
- Regards,
Shawn Beightol
1995 Dodge Ram 2500 Diesel
stock everything
bought the truck at 185k miles, just turned 420k
Audi Engineer's comments on wire contacts:
"Sometimes a poor connection is actually caused by a well meaning person trying to help the problem by using cleaning sprays that contain silicones to make the connections water-repellent. Why is this harmful? This is because silicone when certain conditions exist, can combine with metal ions to form high resistive films such as sodium silicate.
Those of you who have replaced a full throttle switch on a 200 or 5000 turbo engine know that even though the contacts are physically touching no signal gets through the switch.
This highlights that it is more difficult to design a connector to carry a small signal than to carry large current. Contaminant films which would be of little problem for higher current flow will cause conditions in low signal current ranging from zero-crossing distortion to an intermittent connector..."