Three wire Distance Sensor Diagram?

[Ondonti]

My 1992 FSM only has 2 wire sensor diagrams but my 1994 is wired up for a 3 wire. I did not wire it in the first place, a mechanic did 9 years ago since it is 5 speed swapped.

I clipped the speed sensor wire about 8-10 inches from the ecu and lost my speedo. Since the signal wire is supposed to branch off before the ecu, according to the 2 wire diagrams, I was not expecting this.
I know you can run the sensor and speedo without the ECU. What did I screw up?

I cut the wire because the ECU control over AIS using the Distance Sensor has been causing problems with my idle and causing stalling. That problem has gone away with the wire clipped and I was able to drop my throttle stop setting a LOT so the car now decels properly and doesn't want to stall when I take it out of gear (even though I am not being aggressive with the throttle stop anymore).

I need the ecu to not receive distance information and the speedo to still work thanks to the crazy policia here (under the limit, all the time).

[Rampage16V]

I think the white wire with the tracer is the signal. other is 5-8v reference usually orange and black with blue stripe is the signal ground.

[RoadWarrior222]

Dunno if this is any help... http://minimopar.knizefamily.net/speedsensor.html seems to be a few clues there.

[Austrian Dodge]

two-wire VSS:
the sbec supplies the sensor with 5V (white/red wire) and the black/blue wire is GND. the speedo tee's into the white/red wire,
8000 times per mile the sensor shortens the 5V to ground, thats what the speedo is picking up and giving you a certain mph reading.

http://www.turbo-mopar.com/forums/showthread.php?34591-2.4-sneak-preview&p=573789&viewfull=1#post573789
http://www.turbo-mopar.com/forums/showthread.php?34591-2.4-sneak-preview&p=574200&viewfull=1#post574200

the 3-wire VSS is basically a hall effect sensor with 8V power supply, signal wire and GND. except from the power supply wire, the function is the same.

hope that helps

[Murphy]

I've been REALLY wanting to do this for a long time.

[Murphy]

have you taken out your dash and measured the resistance between the dash connector and the SDS to see if there is still connectivity?

[Murphy]

I just tried it and my speedo still works

95 spirit 3.0 originally 670, swapped to 543, 670 harness with factory 3 wire SDS, 93 3.0/543 computer

I cut the white/orange wire about 6" form the ECU, so I could see there were no junctions. I have full connectivity on the white/orange wire between the sensor and the dash connector.

I am kind of worried about the check engine light coming on from not getting an SDS signal, so I might hook it up to a switch

[Austrian Dodge]

the VSS wire goes in to the body computer and cruise control also!

[Murphy]

I'll have to test out the cruise on the way to work tomorrow. I cut it in a location where it would be easy to put back together.

[Murphy]

cruise doesn't work. I'm going to try to wire up a relay so when I turn on the cruise control, it connects the VSS

[Murphy]

hooked up the relay and the cruise kinda works, but if you hit the accel or decel buttons, it goes just accelerates and doesn't stop. I think I need a diode so the relay isn't interfering with the signal to the ECU.

[RoadWarrior222]

hooked up the relay and the cruise kinda works, but if you hit the accel or decel buttons, it goes just accelerates and doesn't stop. I think I need a diode so the relay isn't interfering with the signal to the ECU.

You pulled that relay out of a Toyota didn't you? :D

[Murphy]

Maybe it is, but the brakes, clutch and ignition still work.

I haven't played with it since my last post, but the engine is alot smoother under 2000rpm and it hasn't stalled yet

[Ondonti]

I reconnected the signal and gained back my Speedo. Thing is my speedo wire has something wrong, probably inside the dash wiring. My Cruise stopped working a few years ago, and soon after that I was getting the weird speedo dropping out when I turned the lights on. My fix for that was adding a few grounds and directly grounding the dash. I added a direct ground for the Climate control because that also caused a problem with the speedo. Even when the blinker would blink the speedo would fall down. The grounds fixed all that but after a Long time of driving with my speedo wire hooked back up the ecu (about 2 hours) the speedo finally died agian. Normally it would die in about 10 minutes last year.

I do think I want to rip out the Distance Sensor wire that is in the passenger side harness because I am not using it and thats just another place for it to screw up.

Motor runs SO much better without the signal to ECU, especially with these huge cams. I think I never noticed it on the Duster because it had a different AIS and manifold and I purposely had the idle speed higher. It did behave differently because RPMs would still drop between low rpm shifts with a high idle.

[Force Fed Mopar]

So will a 2-wire sensor send a signal to a 3-wire computer? I have a 3-wire harness and computer, if I run the wires to the right terminals will it work? Or is the 8v feed necessary?

[Austrian Dodge]

the two wire sensor requires the 5v signal from the ECU otherwise it won't work/send signals....three wire sensor is +8V - SIG - GND ...

[Ondonti]

Maybe instead of tearing apart all my wiring I will just "hotwire" the speedo directly from the VSS for the time being and if I feel like cruise control in the future, worry about that later.


Anyone have a good writeup on the cruise control system? Guessing we have to keep the OEM ECU around for that.

[RoadWarrior222]

If you really want cruise, maybe there's a way to get the old style one working.... which is what my '88 has, but it's not been functional while I've had it.. needs cables which seem to have gone unobtanium for years... not that I've tried real hard.

[Force Fed Mopar]

the two wire sensor requires the 5v signal from the ECU otherwise it won't work/send signals....three wire sensor is +8V - SIG - GND ...

Yeah I got to thinking about it later on last night and realized the difference :)

[Ondonti]

So the 3 wire is the trick item to be able to ditch the OEM ecu.

[Austrian Dodge]

you'd need to wire it up correctly, because the 2-wire sensor uses one wire (white/red) as 5V supply and signal -> gets pulled to ground.

using the 2-wire sensor:
get a voltage regulator, solder a 2,7k ohm resistor inline the 5V output of it and you're good to go.
look here: http://www.turbo-mopar.com/forums/showthread.php?34591-2.4-sneak-preview&p=573789&viewfull=1#post573789

using the 3-wire sensor:
use the white/red wire as signal, black remains ground, supply the sensor with 8V (voltage regulator e.g.)

ditch the factory ecu