ABS wire for Superlift's Tru-Speed

[blake underwood]

I have an '04 Dodge and I don't know which wire it is that you tap into for the Tru-Speed tire recalibration. I looked on a guys '03 and the wire is white w/ an orange tracer. The wire on my '04 in that place is black/? Would it be that wire? All the ABS wires are black w/ different colored tracers except one. It's white w/ a purple tracer.



Any help. THANKS

 

[CIverson]

I believe you can tap the sensor at the speedo sensor also, on the rear axle. There should only be 2 wires there so 50/50 chance.



Also, you might take a look at them and note the colors. Might find a same color wire in the harness and give that one a whirl.

 

[nickleinonen]

go here -> http://www.dodge.com/bodybuilder/ <- and you can download for free dodge's wiring diagrams in pdf format. the diagrams list the colors and pin numbers for pretty much all the wiring on the 2004

 

[Udaloy]

Originally posted by CIverson

I believe you can tap the sensor at the speedo sensor also, on the rear axle. There should only be 2 wires there so 50/50 chance.



Also, you might take a look at them and note the colors. Might find a same color wire in the harness and give that one a whirl.

You cannot do that. You have to tap the wires in the engine compartment where the directions indicate. The reason is that there are speed sensors on each front wheel (ABS), and one on the rear axle.

 

[CIverson]

Originally posted by Udaloy

You cannot do that. You have to tap the wires in the engine compartment where the directions indicate. The reason is that there are speed sensors on each front wheel (ABS), and one on the rear axle.

The speed sensors on the front wheels do nothing for the speedometer though. The speedo only gets it's reading from the sensor on the rear axle.



Even when you tap the wire for the speedo, you tap the wire before it gets to the ABS computer, it runs the signal into the box, and converts it, then sends it to the ABS comp.

 

[Udaloy]

What do you think is going to happen when the computer thinks the back wheels are going 50 mph and the fronts are going 55 mph? I believe the wire is tapped after they come together and send your speed to the PCM.

 

[CIverson]

The front wheel sensors are only used for detecting lockup of the wheels, so it can modulate the braking and allow the ABS to work.



If you think about it, the ABS computer dosen't care what speed the tires are moving, only if they lock up, the sensors just want to know that the wheel is moving.

 

[Udaloy]

I was just looking at the wiring diagram, and it shows that everything goes into the Antilock processor, then into the Powertrain Control Module and the Engine Control Module. Once the three inputs on wheel speed enter the Antilock Processor, one vehicle speed input is sent to the ECM and PCM. Which is a better place to alter this signal, before the Antilock Processor or after???



I highly doubt that the processor is ok with two different speeds on the inputs. Wasn't there a thread a while ago discussing antilock braking not working below a certain speed? Or perhaps it was antilock action was happening, even though not warranted? Surely there's a technician out there that can spread a little more light on this.



Here's a link to the diagram showing all three wheel sensors going into the processor.



Wiring Diagram

 

[CIverson]

I understand what your thinking, but I only see the front sensors as detecting lockup. Reason I think that is if you disconnect the speed sensor on the rear axle, you have no speedometer. If the front sensors worked in the capacity that you are thinking they do, then one would propose that you could still get a speedo reading.



I will admit that I'm not 100% positive, I'm just making educated opinions from the truespeed installs I've done, and my experience w/ having no speedometer.