ABS and brake light Code CO238

Boomer

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#1
2002 Chevy S10 pickup. ZR2 123,000 I took my scan tool (Actron CP 9580A) and cleared the codes. I hopped in the truck today and drove about 20 miles. No lights at all. I was parked about 20 minutes. I came out, started the truck and the ABS and brake light were both on. I was running some errands. Sometimes it would come on when I started it but, not every time. I got home and checked the code. It was CO 238. Wheel speed mismatch. The frequently reported fix from the scan tool is to "program the PCM". According to the tool, a frequently reported fix is as likely a fix as any other. Since I don't have a Tech 2, I need to eliminate all other possibilities first. The tires are new and factory sized 31 x 10.50. Have you guys come across this before?
 
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#2
With erratic operation like this, typically a corroded wheel sensor connector. Can make good contact when cold, breaks when heated up.



Yes I ran into this before.
 

Boomer

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NickD said:
With erratic operation like this, typically a corroded wheel sensor connector. Can make good contact when cold, breaks when heated up.



Yes I ran into this before.
Hey thanks Nick, is there any way of telling which one or, do you just have to get at all of them?
 
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#4
Being a ZR2 - I am not sure- 4 wheel speed sensors OR 2 front and 1 rear speed sensor?


with your scanner* look at all the wheel speed sensor readings-
are they all reporting?
speedometer works?
any more than 10 mph different than speedometer?
Are all 4 tires new and same as data decal driver door?
with a DVOM - at the least 350 ACmV's...... note AC voltage...


* getting old saying that - a must have in todays world...
 

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kev2 said:
Being a ZR2 - I am not sure- 4 wheel speed sensors OR 2 front and 1 rear speed sensor?


with your scanner* look at all the wheel speed sensor readings-
are they all reporting?
speedometer works?
any more than 10 mph different than speedometer?
Are all 4 tires new and same as data decal driver door?


* getting old saying that - a must have in todays world...
Hey Kev, not positive on the number of sensors. It does have 4 wheel disc brakes. I don't know if that matters or not. I'm brand new to this scanner so, can I monitor this while driving?

Tires are new and same as data decal. 31 x 10.50 BF Goodrich which the truck came stock with. I have previously spun both front wheels while reading the AC voltage on my multimeter and both were above 350 mv but, while I'm thinking about this, it did seem like I got the passenger side to 400 but, not the driver side. Now I was by myself so one hand holding both leads in the connector while the other spun the tire so maybe I just spun one faster than the other.
 
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#6
that ZR2 was the limited off road option- and the reason I asked, most base models used the transfer case sensor for rear wheel speed - the ZR might have snsors at the rear calipers much like the front wheel.

I do not know that scanner SO it is a learning curve for you - utilize their web site customer service maybe they will actually provide service....

I will double check that ZR2 being 3 or 4 wheel sensors
 

Boomer

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I know the scanner says it monitors live data so I will hook it up and take a ride and see what all it records or monitors. It says record and playback data.
 

nickb2

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#8
It looks like a tire mismatch but you say they are stock. It may need a ECBM recalibration. I am not much help and looked up C0238. Not much to go on. Here is the chart, hope it helps, but I doubt it.

To the looks of it, may need Tech2 and a reflash of module.

This may sound funny, but have seen codes like this when burning rubber or when I check wheel speed sensors on a lift or jacked and one of the wheels spins faster than the others. Erase the code and see if it comes back.

Had to modify, I checked out the actron official site, the series with "a" is abs friendly, might give wheel speed data. Hope so. I did read the manual for the actron, (yes I am crazy) amd did not see any pid data for wheel speed sensors or anything else ABS related. It just seems to be able to read C codes and not much more. Pages 105-120 of guide book. http://www.actron.com/publish/2012/08/21/pdf_english_16366.pdf
 

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Boomer

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#9
Thank you Nickb2,

I went for a drive and didn't see the wheel speed sensor information. I just got off the phone with Actron tech support and the guy said basically the same thing. He wasn't sure but, he didn't think the tool was capable of reading wheel speed sensors. He also said he would email me a better guide than the little 10 page quick start guide I had. I'm going to say it's probably the same thing you just linked to. This will help me learn the tool better. The quick start guide is almost useless. It doesn't tell you much.

Since all of my vehicles are Chevrolet, maybe I should have bought a tech 2 but, that seems expensive for a DIYer. Actually seeing it online for a little over $300. I spent $137.50 for this Actron.

The truck is acting like NickD said in reply number 1 though. No light was on during the trip I just took but, it was probably only a couple of miles. Maybe I should check the wheel sensors. I have nothing to lose.
 

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Update:

I pulled the front driver side apart and this is what the sensor looks like. That appears to be a red colored grease. Other than that, it looks pretty clean. Do I need to do anything?



 

Boomer

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#11
:( Well, I put it back together and now have a solid ABS light and a code of C0225. Left front wheel sensor open or shorted. I took it back apart and tried to see if I had missed anything but, all was normal. I heeded the warnings from alldata to pull the sensor straight out and not pry with a screwdriver. You can see in the pictures above, it doesn't look mangled. I don't think it's shorted because I took the connector apart that is mounted on the frame and ran a continuity check and there wasn't any continuity. I then switched my multimeter to ACmv and spun the tire and there is no reading now so, I'd say it's open.

How could I have messed it up just taking it out? I will say it came out rather hard but, it's been sitting in the hole for 12 years so I suppose it's not a shock. Is it my fault or, have you experienced one just quitting after being disturbed? Finally is Rockauto the best place to get a new one? Thanks alot guys. I appreciate all of your help.
 
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#12
Looks pretty rusty, must be in the road salt area, Unfortunately with uneven pulses, scanner only shows either the front or the rear, but can be on either side. So both sides have to be checked.

What the common sensor is, is a permanent magnet about 1/8" in diameter, half inch long with a coil of wire wrapped on it, not even layer wound, random wound where just one shorted turn can kill the pulse, and typically use 44 AWG wire, not even as thick as a human hair. Cheap as you can make it.

Then the sprocket itself with teeth that can fill up with ferrous oxide, a variable reluctance device that depends on a variable magnetic flux to induce a marginal voltage. This can also be the problem with a misfire with the added problem on some vehicles to pull the hub to get at it.

Some Stanford profession playing with his laptop and statistics came up with ABS equipped vehicles are 14% safer with ABS, therefore our congress passed in law, all vehicles made since 2010 must be equipped with ABS. To reduce cost, automotive manufacturers are even making these systems cheaper than before, and next to impossible to even bleed your brakes without a way overpriced interactive scanner.

I see now finally, low priced scanners are reading ABS codes, ABS is suppose to be a supplementary system and not interfere with normal braking, but yet, anyone can play with their brakes. But these are not interactive for proper brake bleeding.

And say the ABS does not interfere with normal braking is an absolute blatant lie. If a cheap made in China transistor shorts out activating all of the valve solenoids, won't get any braking at all. Already ran into this. But have idiots running this country.

ABS is only for people that don't know how to drive. Rest of us have to pay the price for these idiots, also makes them artificially more self confident because they have ABS.

Have fun.
 

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#13
It is in Illinois. It actually looks clean down in the hole. The picture doesn't show it very well. Hard to get light in there and hold and operate the camera by myself. I did notice when I took it back out the second time that some of the strands were coming off. You're right, they are very thin. Have you killed a working one just by pulling it out?

I ordered a brand new AC Delco one from Ebay. It has the same part number as rock auto. Got it for $34.76 so around $20 cheaper than rock auto. Do I need to aquire some of that red grease when I put the new one in?
 
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#15
What big plastic part? What picture? If you are talking about what I might see if I click your "Ebay" link, well it shows me some pretty dresses.

I had a second look at your "removed sensor" pics...hard to be sure with the angle of the shot, but I think you pulled out only the core, leaving the exterior shell still in the hub. You said "strands"? That sensor is toast.