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Speed Sensors on A518's

Posted By: IMGTX

Speed Sensors on A518's - 04/21/08 09:49 PM

I am currently swapping an 5.9 magnum & A518 into my car. I am keeping the factory EFI, Computer etc. My current hitch is the speed Sensor.

The OEM one in 94 was a 3 wire unit with no provisions for a speedometer cable. I want to use the factory Speedo but need the signal for the Engine Controller.

I picked up a pass through speed sensor off of a Dodge van but it only has 2 wires instead of three.

Is this adaptable or do I need to look elsewhere?
Posted By: MarkZ

Re: Speed Sensors on A518's - 04/21/08 10:06 PM

Try a speed sensor from something earlier. I pulled my 500 out of an early Dakota that had a mechanical speedometer. The speed sensor had provisions for a cable.
Posted By: stockerbill

Re: Speed Sensors on A518's - 04/21/08 10:33 PM

Here ya go!I am doing a 6.1 with a viper 6 speed in a early b body and this unit will work with your elect drive train and a cable speedo(a little pricy but accurate!!) It is a stand alone unit to drive the cable http://www.abbott-tach.com/cablex.htm
Posted By: DartGTDan

Re: Speed Sensors on A518's - 04/21/08 10:34 PM

I believe its a choice of the mechanical cable, or the electronic speed signal. I don't think you can run the Engine Controller without the electronic speed signal.
Posted By: stockerbill

Re: Speed Sensors on A518's - 04/21/08 10:36 PM

forgot the link http://www.abbott-tach.com/cablex.htm
Posted By: IMGTX

Re: Speed Sensors on A518's - 04/21/08 11:31 PM

Quote:

I believe its a choice of the mechanical cable, or the electronic speed signal. I don't think you can run the Engine Controller without the electronic speed signal.



Yeah I need the electronic signal and the mecanical cable. The device I got the other day looks like this. It's a speed sensor that connects in between the cable and the speedo gear housing. It would work except the wiring harness for the 94 has 3 wires and the speed sensor I have has two. I am hoping their is a way to adapt it.

Attached picture 4374278-wl2su334003.jpg
Posted By: John_Kunkel

Re: Speed Sensors on A518's - 04/22/08 12:05 AM


The hole in the '94 tailhousing is the same as the older cable drive, just install the cable adapter and pinion from an older unit and you will have a threaded cable adapter.
Posted By: 383man

Re: Speed Sensors on A518's - 04/22/08 09:55 AM

What year is the trans you are putting in ? Ron
Posted By: patrick

Re: Speed Sensors on A518's - 04/22/08 12:13 PM

Quote:


The hole in the '94 tailhousing is the same as the older cable drive, just install the cable adapter and pinion from an older unit and you will have a threaded cable adapter.



since he's keeping the EFI, he needs both the VSS output AND the cable drive....

Quote:

Quote:

I believe its a choice of the mechanical cable, or the electronic speed signal. I don't think you can run the Engine Controller without the electronic speed signal.



Yeah I need the electronic signal and the mecanical cable. The device I got the other day looks like this. It's a speed sensor that connects in between the cable and the speedo gear housing. It would work except the wiring harness for the 94 has 3 wires and the speed sensor I have has two. I am hoping their is a way to adapt it.



can you get wiring harnesses and find out what each wire is used for? maybe the 3rd wire is a ground that's not needed?
Posted By: dogdays

Re: Speed Sensors on A518's - 04/22/08 01:56 PM

My thoughts exactly. The third wire may be nothing more than a ground.

For example: Oxygen sensors with three wires have one ground wire for the heating element and I presume the O2 sensor ground is through the case same as a one-wire.
However, four wire O2 sensors have two ground wires, one for the heater element and one for the sensor ground.

It could be the same way for the speed sensor.

R.
Posted By: IMGTX

Re: Speed Sensors on A518's - 04/22/08 08:53 PM

OK here is the Wiring diagram I have for the Vehicle Speed Sensor that came in the 94 Transmission I am using.

It appears that it recieves a Positive 8v, a Ground(sensor return) and a signal from the VSS.

Any good ideas?

Attached picture 4376646-wiringforVSS.JPG
Posted By: Anonymous

Re: Speed Sensors on A518's - 04/22/08 10:25 PM

Mopar part 4439097 is an in line sensor from
say an 89 M body. You should be able to use your
old pinion holder adapter into the new trans tail
and put the electical piece in line. I am not sure
if that sensor has a 5 volt signal but it may work. Check wiring for an 89 M body.
There is also 4740088 which if for a FWD and may be what you have, I'm not sure.Hope this helps.Try not using the black with blue tracer as this is the sensor ground.
Posted By: patrick

Re: Speed Sensors on A518's - 04/23/08 12:39 PM

Quote:

OK here is the Wiring diagram I have for the Vehicle Speed Sensor that came in the 94 Transmission I am using.

It appears that it recieves a Positive 8v, a Ground(sensor return) and a signal from the VSS.

Any good ideas?



can you get your hands on a similar vintage (or TBI) dakota or van service manual? IIRC those used a cable driven speedo and VSS

check that...look up a 1993 dodge dakota...it's VSS is standard motor SC108 (rockauto sells for $101)

http://www.partsamerica.com/ProductDetai...179&PTSet=A

a '93 dakota uses a magnum 3.9 or 5.2 engine, so it should work, you'll just need to find a wiring diagram for it.
Posted By: DaytonaTurbo

Re: Speed Sensors on A518's - 04/23/08 03:34 PM

Go to the junkyard and grab a speed sensor from a 4cyl FWD mopar. Judging by that pic you posted, the speed sensors look to be the same. They were also a 3-wire and many of them where a pass through design to accomodate a speedo cable as well.
Posted By: IMGTX

Re: Speed Sensors on A518's - 04/23/08 08:02 PM

Thank you for all the info.

I haven't found the solution yet but with all this info I have lots of options.


If you have other suggestions let me know and I will let you know what I find to work.
Posted By: kim smith

Re: Speed Sensors on A518's - 05/21/10 01:55 PM

Check out http://cmacable.com. I worked with them through the entire process of modifying my ATV. They have A+ customer service and an excellent line of cable and restraints. If you are looking for Mechanical Cables cma is the way to go!

Posted By: RodStRace

Re: Speed Sensors on A518's - 05/21/10 02:26 PM

Just for reference, a 2 wire signal is probably providing a voltage with a round wave pattern (analog) and the change is often more waves with speed AND amplitude (voltage increase with speed increase.)
A 3 wire sensor is probably a hall effect. This sends out a square wave (digital) with pulses. Faster is more pulses.

Attached picture 5995129-2wire.gif
Posted By: 383man

383man - 05/22/10 02:59 PM

Quote:

Just for reference, a 2 wire signal is probably providing a voltage with a round wave pattern (analog) and the change is often more waves with speed AND amplitude (voltage increase with speed increase.)
A 3 wire sensor is probably a hall effect. This sends out a square wave (digital) with pulses. Faster is more pulses.




Yes the 2 wire speed sensors send a small ac anolog voltage signal and the 3 wire sensors send a digital hall effect signal as they are hall effect sensors.
The 2 wire ac sensors in the tailhousing of the 518 is not used for the speedo but it is used for the electronic govenor as it needs to know the output shaft speed to control throttle pressure. These vehicles usually use the rear diff 2 wire sensor for the abs for the speedo. The abs module sends the signal to the pcm as it is either hard wired or sent over the buss. Then it goes to the cluster. Ron
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