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JoeK
Dodge Dakota
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8/17/2004
11:41:41
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 Subject: Remote Throttle Position Sensing
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I want to add a gauge to my 4.7dak-5spd to display the position of the throttle. (Why? I don't know other than to say that I am a gas efficiency nut and want the feedback to improve my mileage).
I am thinking of tapping into the throttle position sensor, which outputs a 0-5 volt signal, which I can cross to a throttle position. The manual says that closed throttle is around .3 volts and wide open throttle is around 4.? (I forget) volts, so the gauge scaling is straight forward.
Is there an easier way? For example, can I tap into the PCM data bus and pull it off of there? I couldn't find a spec in the manual for the data that is on the PCM bus. I suspect, based on the manual, that the analog voltage signal from the TPS is used as an input by the computer, but the position data is not put out on the bus for use by anything else.
Any ideas?
Any existing products out there?
PS: This is my first dak, have always been a ford person. Have had it about a year now and am very happy with it!
Thanks,
Joe Kubinec
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Kowalski
GenIII
8/17/2004
15:25:08
| RE: Remote Throttle Position Sensing
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Wouldn't you do better with a vacuum gauge, driving to highest vacuum ?
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greyDAK
Dodge Dakota
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8/17/2004
19:06:27
|  RE: Remote Throttle Position Sensing
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Your idea of a guage would be pretty simple enough. A dial meter from the local electronics store would be good enough to measure the scale or you could use the LM3916 dot/bar display driver and make a bar graph that would show 0 to 5 volts in 10 steps. The electronics are simple and you can wire wrap the circuit so you wont need to etch a circuit board. Take a look at the pdf from National Semiconductor LM3916 Data Sheet.
It would be an interesting project that if you did it with photos others here would probably follow suite.
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gen1dak
Dodge Dakota
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8/17/2004
21:39:48
| RE: Remote Throttle Position Sensing
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Like Kowalski said, the vacuum gauge has been used for decades to do this very thing. They are even sold with gauge faces that show best power and best economy. Just look in the JCWhitney catalog.
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greyDAK
Dodge Dakota
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8/17/2004
22:21:09
| RE: Remote Throttle Position Sensing
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while I agree in principle with the use of a vacuum gauge, for someone who is looking for a neat little project its better than just wireing up someone elses work. The chip, LEDs and bits and pieces will cost less than $10, plus the work in assembly and test and the ultimate wireing would be a lot more fun, indeed.
But thats strictly my opinion and I am in no way saying one way is better than the other for the needed application - just a different way to go.
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JoeK
Dodge Dakota
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8/18/2004
08:31:06
| RE: Remote Throttle Position Sensing
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I thought about the vacccum gauge approach, but wanted to go the analog route as a 'hobby' to get into the vehicle's electronics a bit.
Thanks for everyone's advice. I'll re-post when I get something working.
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Kowalski
GenIII
8/18/2004
18:15:43
|  RE: Remote Throttle Position Sensing
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Sounds like an interesting project; some of you guys seem pretty sharp with the electronics. Anyone got an easy way for me to make my auxillary outlet controled by ignition switch so I don't have to remember to turn my radar detector on or off ?
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greyDAK
Dodge Dakota
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8/18/2004
18:24:07
|  RE: Remote Throttle Position Sensing
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that shouldnt be too hard. My Dak didnt come with oem driving lights in the lower valence of the front bumper. I couldnt justify the Chryco price for their solution, and the local car shop's prices were pretty high too, so I wound up waiting for a surplus sale at the surplus store. The lights came without any harness at all so I needed to make my own. A nifty switch in the stock location, a green LED when its on, and a 30 amp relay allows these lights to come right off the battery, but are switched with the key (if the key is off, the driving lights are off too regardless of the on/off switch). Its been on the truck for about 2 years and still work like a charm. An accessory jack (12 volt outlet) can be wired up in a similar manner.
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Kowalski
GenIII
8/18/2004
18:52:02
| RE: Remote Throttle Position Sensing
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Not a bad suggestion; but mine came with the those lights - any other ideas ? If I didn't have those lights I'd be tempted to use those circular areas in the valence for some brake cooling ducts. If I didn't already have so many different projects (not truck related) it would be tempting to combine these 2 ideas, using that switched power source to also run a couple of bilge blower vents for the brakes.
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Noltz
Dodge Dakota
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8/19/2004
23:44:18
| RE: Remote Throttle Position Sensing
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Adding a blower to cool the brakes is, IMO, over the top for a street truck. Of course unless you have the power to back it up.
As for a switched outlet for your radar detector, it would be wired just as greyDAK's lights. You would tap into the stock cig lighter for your power source, since it's already fused and everything. Use a 30A relay triggered by a "hot in accessory only" wire from the ignition to supply power to an added-in cig lighter for your detector.
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jaggy
GenIII
8/20/2004
11:38:47
| RE: Remote Throttle Position Sensing
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There are a couple of key on blocks in the fuse pannel as well. Get a voltmeater and find a good ground. ( I use the door latch) and find one that is hot when the key is on. turn off and confirm that it is off. I suggest the fuse block for the radar because it is so low amprage. I have mine piggiebacked off of my radio fuse with an aditional 1 amp fuse inline. And you certainly would not want to use a 30A relay! Damn I have reverse driveing lights running on a 30 amp.
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wadak
GenIII
8/21/2004
04:05:52
| RE: Remote Throttle Position Sensing
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Kowalski
Have you ever checked your 0-60 mph with the snow blade on just curious?
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Kowalski
GenIII
8/21/2004
07:28:10
| RE: Remote Throttle Position Sensing
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Thanks guys, I guess I'll just run a new wire to a piggy back connecter on a switched fuse. I knew there were some tricks that could be done moving fuses to do this on mopar's mini vans, was hoping there might be a simple solution like that for our trucks.
Noltz - if you've ever had your brakes fade towing on a long downhill run, like I have, you might understand its not just racing conditions where we see problems with the front brakes on our trucks. Surge boat trailer brakes don't work as well as electric brakes on a downhill stretch like that; I have to drop to 2nd gear in my auto tranny on one stretch I run to avoid overheating the brakes.
wadak - I'll bet my truck carrying the plow can beat your unloaded six banger to 60 any day of the week. Bring it on, laughing boy.
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