i got bored... antilock light diagnoses
 

well for a little while now my low-trac light comes on and sometimes is accomponied by traction control preactivation and trac-off and antilock lights coming on.



i dont hear any funny noises going down the road. no growling, no scraping. 9/10 times a loose wheel bearing causes this concern so i checked mine as followed:

raised the alero, make sure to raise it safely. as you can see i lifted mine more in the center up front rather then on the pinch welds. over time the pinch welds can get weak and with all the weight of a FWD being up front it can cause it to crush.

wiggled the wheel at 9 and 3 oclock to check tierod ends (if a wheel bearing is loose enough you will feel it here too.

then 12 and 6 oclock. this wheel tell you if you have a loose bearing. everythings tight on my car.

next thing i did was check to make sure nothing was starting to come unhooked. usualy you find the sensor connectors have come off the knucle and rubbed on cv-shaft. inspected all my wiring and it all looks good except for the RF hub connector that shows signs of corrosion because the rubber seal around the connector has been cut:

yesterday i tried cleaning that up a bit and it seems to have made a differnce but did not fix it. FOR NOW IM GOING TO IGNORE THIS

USUALY by this point you will have found your problem and know what needs fixing. but as you can see i havnt. working at a dealer i have access to a techII so i went and checked codes and also took a snapshot of my wheel speed sensors:
"C1226 right front excessive wheel speed sensor variation." so im focusing on the right front wheel at this point. i go head and take a snap shot of when my traciton control activates and see whats happening:
found it. as you can see by the little dotted line (Which is the RF) what peaks WAY before the LF and Vehicle Speed do. so there is deffinitly a problem.

next i check the hubs for Ohms and MvAC. i have a very good idea what the spec is however i dont know for sure. so... i compare sides. >UPDATE< adding specs: ohms should be 1040-1160. mVAC should be equal to or greater than 100mV.
To measure ohms you unhook the wheel speed sensor and with a DVOM you check resistance across both terminals on the hub. i have an old "car side" harness pigtail with aligator clips to test these. makes it a breaze.
to measure Mv you test the same way except in MvAC or ACv depending on your meater and spin the hub as fast as you can by hand.
RF Ohms and Mv:


everything looks good there. and compare nicely with the other side. crap.
so the next step is to go a little further and do the same test at the EBCM (electronic brake control module). on our cars it located inside the washer fluid jug in the drivers front fender:

heres the connector:



next thing im going to do is test the front hubs JUST like i did before but at the EBCM. this will test ALL the wires from the EBCM to the hubs.
terminals 9 and 22 go to the RF wheel. terminals 8 and 21 go the LF. make sure to use the right test equipment because these terminals can get damaged easily.
everything checked out there:


hmmm so all thats good. well i have three choices... either a new EBCM, attack the corrosion on the car side harness, or throw a hub at it...

ebcm is expensive... yuck, and i dont have a hub with me nor do i feel like replacing it right now. so lets check out that connector on the RF hub.
here it is:

next thing im going to do is remove the CPA from the back of the connector:

followed by removing the terminals from the connector with my specialy calibrated terminal removal tool:

heres the two terminals, hard to tell but one of the terminals is a little green:

snip snip
in the process of stripping the wires i noticed this:

the light spot on the green wire is where the insulation is stretching because the wires broke. BOTH wires did this right about where they bend up from the control arm and go up the hub.time to cut some more wire off.
next thing i did was take a donor connector and remove its terminals and wires:

the PROPER thing to do would have been to replace the terminals but seeings how the wires broke as well i just butt-spliced these two wires in its place. and re-installed in the connector:

re-installed the connector and the front wheels (take them off isnt necessary but i did it for ease of picture taking.
test drove and at this moment it appears to be fixed.


I want to add something i found last weekend. unfortunitly i was not able to go in depth to share on here due to time. the alero once again had an abs light on. still has both repairs and same hubs as it did when i posted this. it was setting a code for left front wheel speed sensor short or open. forget the code number though. i checked ohms and it was good. even mv (spinning the wheel brought over 150mV no problem). even compared specs to the other sensor. i was at a loss for sure. i happend to be watching wheel speed sensors with the scan tool while the vheicle was on the lift (key on engine off) and left front wheel speed was jumping all over the place (0-10mph). what the hell eh?

what i did was ran jumper wires from the left front hub to the right front vehicle harness. then jumper wires from right front hub to left front vehicle harness. wheel speed now read on right front. never seen it before but i think salt water has gotten into the hub and causing false voltage. just wanted to add.

Nice walk through there. That should be a big help to guys with similar issues, good picks too.... good job man!

thanks alot mmgt

So, if I'm hearing a grinding/moaning noise from the front wheels, it's most likely the bearings?

can also be brakes

the "typical" noise you get with bad bearings is a howl that changes with cornering. such as going left the noise is quiet and going right the noise is more pronounced. or vis-versa. ride on a bearing long enough and it can also make binding, grinding, popping noises too

It does it when going over bumps, somewhat rough roads, and just general driving.... I can get a video of it and post up... It's gotten worse and has spread to both front tires now.. Use to only be on the passenger side.

At first I was going say "HUBS!" but then I read I read. Nice write up!

thanks. when i get bored enough shit tends to happen. lol anyone consider this worthy of being a sticky?

Cavaliers60 - My '03 did the same thing back in the spring and it was a bearing that was gone.

UPDATE added specs to write up. see original write up.

also note: this is a very good way to diag a LOT of gm front hubs.

This needs to be in the How - To Section. And great job on writeup!!!

yeaha it was my fault for putting it here. if somone wnats to move it feel free.

alright everyone.... My antilock lights back on and iv got a sneaking suspision its the drivers side now. Sooo.... I want to ask if u guys have any requests when i tear into this thing. Anyone feel something needs going over in better detail or w.e?! wont hurt my feelings im just trying to get EVERYTHING covered the best it can be.

Nice write up. This is a good informational directive in situations where most people think that if you get a code, a physically moving part is to blame; when in reality it can be a wire.

alright guys so i dug into my current abs light, sorry for the MASSIVE pictures, i cant get them to re-size for some reason.
the lights are on solid every time the ignition is on so i know i have a "hard" fault. i check the abs DTCs with our Tech II and heres what i have for current



history codes:


the typical signs of a loose hub/bad wire/sensor : sensor variation, open or shorted, signal = 0. good idication your going to need to look at sensors and hubs when you have all three codes show up.

obvously i have a problem with the left front wheel this time. prevously it was an issue with the right front.

i lifted the vehicle (view pictures from first post to see how i lifted my car) and checked the front end for play (once again see pics from first post). still no play in the front end.

got under the car and this is what i found when i inspected the wheel speed sensor:



in my first post i mentioned how a lot of times the harness comes undone at the knuckle and rubs on the cv shaft.. well ta-da! if you look close you can see the problem in that pic right there... in this case it hasnt had a chance to rub on the cv shaft yet but still bad enough.

what had happend is once the connector came unclipped from the knuckle the harness got caught up in the ball joint and broke one of the wires with all that movement:



mind you the correct repair would be to replace the hub. i really really dont wnat to spend the money so im going to booger it together. i rummaged through our scrap pile and found an old hub off of an '06 silverado and a hub off of problably a newer impalla??? and stole the harnesses:

the long harness is off of the silverado. i want a new connector and a short lead of wires for my repair. the silverado harness will work in a pinch but needs to be modified (see secound photo)


the connector from the silverado (upper connector in pic) has a center "devider" in the connector and thats the main thing stopping you from using it as a donor. i have been able to make them work in the past (for test equipment) but it usually makes a mess of the connector.

i went and took the impalla harness and stipped the wires and splice on HEAT SHRINK butt splices:



i then cut off the remaining connector on my car and heres a pic with the old connector (white) and the silverado connector (black):



removed the retainer and set aside for now:


removed the sheith from the hub harness and spliced the wires. cut an inch off the sheeth and slid it back on:





one wire (the one that was broken) has already turned black. sign of water intrusion. im not replacing the hub so its going ot have to work.



spliced both wires together and shrunk the splices




installed the factory retainer and installed on knuckle. the harness is a little long but what more do you want? saved me 60 bucks lol

Thanks, I appreciate the real-world how-to. If you can stay bored, you'll get a lot done. ;)

Great write up and great pics !!!

thanks.

grrrrrr.

now i have a weekend project.

i wanted to go off-roading, but NOOOOOOOOOOOOOOO.

you had to go and do a great writeup!!

:P

hahaha doing my part to cause hate-and-discontent :D