ground?

danielc24 · Post by **danielc24** » Tue Aug 28, 2007 7:40 pm

i changed my front brake pads last week and when i got done with the passenger side i noticed a wire just hanging there. It looked like someone cut it but it must have been a while ago because there was some corrosion on it. It comes from the engine bay and connects to the strut or somewhere in that area, what is it? i hooked it back up but i didn't notice anything...

evilneon02 · Post by **evilneon02** » Tue Aug 28, 2007 7:57 pm

color is the wire it sounds like a ground to me

danielc24 · Post by **danielc24** » Tue Aug 28, 2007 8:09 pm

its black, but what would it be a ground for?

atom · Post by **atom** » Tue Aug 28, 2007 8:24 pm

Hey man, same thing when I did my brakes a couple days ago. Passenger side looked like it was cut clean, not ripped. Strange. But yeah its ground to prevent static buildup in the brake system.

fixitmattman · Post by **fixitmattman** » Tue Aug 28, 2007 8:50 pm

Considering the brake system is isolated from the rest of the car with rubber I highly doubt that's its function.

If the wire goes from the strut to the body, I wonder what it could be grounding

Either way, pretty sure all mine fell off years ago. No big deal, I like to consider it a form of weight reduction.

deep1ca · Post by **deep1ca** » Tue Aug 28, 2007 9:19 pm

I noticed mine was missing too on the passenger side, no idea what its for, haven't replaced it and i've had no problems.

Jamie · Post by **Jamie** » Tue Aug 28, 2007 9:44 pm

I always thought it was a ground for some kind of wheel sensor for the ABS.. just a shot in the dark... that is of course if this wire is the one your talking about.

found this for you.

The wheel speed sensor operates on electronic energy supplied by the CAB and outputs a square wave signal whose current alternates between two constant levels. Its frequency is proportional to the speed of the tone wheel. The output is available as long as the sensor is powered and its state (high or low) corresponds to the presence or absence of tone wheel teeth. The output signal is sent to the CAB. If a wheel locking tendency is detected by the CAB, it will then modulate hydraulic pressure via the HCU to prevent the wheel(s) from locking.

so this infact could be a ground strap for the abs to make sure it has a nice stable ground so the abs sensor can develop an accurate signal in the chance that you do have to lock them down. so i guess it wont hurt anything that they are not there but my children ride in my car with me and this could be a safety issue that i will not jepordize!

hope it helps
J

fixitmattman · Post by **fixitmattman** » Tue Aug 28, 2007 9:52 pm

ABS speed sensor works off the hall effect, similar to the crank sensor. No ground needed, it's not for the ABS that's for sure.

Jamie · Post by **Jamie** » Tue Aug 28, 2007 10:06 pm

sorry that came strait from the DSM...

ill quote the entire paragraph. I offered it as it could possibly be there to equalize any uneven grounding between the wheels so that sensor gets a good reading.

Chrysler DSM
"At each wheel of the vehicle there is one wheel speed sensor (WSS) and one tone wheel. Each front wheel speed sensor is attached to a boss in the steering knuckle. The front tone wheel is part of the driveshaft outboard constant velocity joint. The rear wheel speed sensor is mounted to the rear disc brake adapter. The rear tone wheel is an integral part of the rear wheel hub and bearing.
The wheel speed sensor operates on electronic energy supplied by the CAB and outputs a square wave signal whose current alternates between two constant levels. Its frequency is proportional to the speed of the tone wheel. The output is available as long as the sensor is powered and its state (high or low) corresponds to the presence or absence of tone wheel teeth. The output signal is sent to the CAB. If a wheel locking tendency is detected by the CAB, it will then modulate hydraulic pressure via the HCU to prevent the wheel(s) from locking.
Correct ABS operation is dependent on accurate wheel speed signals. The vehicle's tires and wheels all must be the same size and type to generate accurate signals. Variations in tire and wheel size can produce inaccurate wheel speed signals.
Improper speed sensor-to-tone wheel clearance can cause erratic speed sensor signals. The speed sensor air gap is not adjustable, but should be checked when applicable. Wheel speed sensor-to-tone wheel clearance specifications can be found in Specifications."

fixitmattman · Post by **fixitmattman** » Tue Aug 28, 2007 10:50 pm

That's great. We know how the pickup wheel works. Where does it mention chassis ground in there again? There is no sensor grounding through the sensor body. Three wires in a hall sensor, power (normally 5v) COMPUTER SUPPLIED GROUND, and signal wire. Everything is internal to the sensor. Three wires in, no chassis ground.

Jamie · Post by **Jamie** » Wed Aug 29, 2007 12:49 am

wrong again. the computer does not control the abs, an actual electronic brake control module controls the activation of the abs. and it is 12v switched from the power distribution center. when there is a problem it sends a signal to the light in the dash. this info is strait from the dsm. and wrong agian it is not a hall sensor with 3 wires, the it is two wires from the vehicle speed sensors to the electronic brake control module. i can give you the colors of the wires if you like.

you use a ground strap like that one to equalize the charges between the two metals. just like airplanes. you ground the airplane to the fuel truck to avoid a difference in charges. the airplane would be an extreme case when compared to our cars but the difference in charges in aircraft could cause a spark and ignite fuel. its the same reason you drag your feet across the carpet. and get shocked when you touch the door knob. now in our sake maybe they put the ground strap there to make sure there is an equal charge across the parts of the vehicle to insure little interfience by difference of charges when it comes to sensors... I will concede the fact that i did not find that wire in the dsm however that would be a common sence reason to install one.

is it a necessary wire, no. we all know that, will your car explode into millions of pieces with out it... no. could it ensure a cleaner signal that the traction control or the wheel speed sensers recieve when it comes to slamming on your brakes to avoid creaming the kid chasing his ball... maybe...

no need to be smart about it... this isnt the .org. Im done with this topic

good luck tuning
J

deep1ca · Post by **deep1ca** » Wed Aug 29, 2007 1:51 am

I don't think its for abs. I have the grounds on my car but my car doesn't have abs.

...wish it had abs.

Post by **jonnymopar** » Wed Aug 29, 2007 9:27 am

deep1ca wrote:I don't think its for abs. I have the grounds on my car but my car doesn't have abs.

...wish it had abs.

Got them on mine too. I'm actually missing the body plug that holds it in, but it's there. My car doesn't have ABS. Damn glad it doesn't.

Mr Josh Zombie · Post by **Mr Josh Zombie** » Wed Aug 29, 2007 9:30 am

I have those wires just hanging as well. Lost the nuts for 'em awhile ago.

Maybe I'll go cut them off tonight. No one seems to know what purpose they serve, and I sure as hell don't have ABS.

Post by **occasional demons** » Wed Aug 29, 2007 9:51 am

They are a throw back from the eighties front wheel drive cars. The static electricity would arc in the wheel bearings and fry them. My Dad's Omni would toast a wheel bearing in 20,000 miles or less if the ground corroded. Doesn't seem to be an issue now, but I think DCX put them there as cheap insurance. They cost around $10 each if I remember correctly....