aweil

I have been getting a C1233 code, RF wheel speed sensor open or shorted. I tried swapping the small wiring harnesses from RF to LF wheel, and I still get the 1233 code which leads me to believe that the problem is either in the sensor or somewhere else in the wiring... does anyone have any suggestions before I buy a new RF wheel speed sensor?

Thanks!

Andrew

trussme

Wheel Speed Sensors

Codes C1221 thru 1228 indicate that one of the wheel speed sensors is either sending a bad signal or no signal. Start by checking the connections. The wheel speed sensors are integrated into the wheel bearing/hub assembly pictured below. The wire coming out of the back is the connection for the wheel speed sensors. Verify that the connector are not broken, damaged, or corroded in any way. Pay particular attention to the female end.




The wire coming out of the wheel speed sensor connects to and 18" jumper harness, then to the main harness. It is very common for people to have a weak female pin in one of those connections. If all of that checks out good, Swap the jumper harness from side to side. For example if the left front is bad, swap it over to the right front. and install the good one from the right front to the left side. Then clear the trouble code. If the trouble code is now on the right side, you know the wire harness is the problem. If the code is still on the left side after swapping the jumper harnesses, you know the problem is inside the wheel speed sensors.


If all the wires check out good, it's time to take a trip to Auto Zone for a new set of bearings. You can buy replacement AC Delco bearing from your dealer if you want to, or get the exact same bearing in a different box for half the price (~$150) from Auto Zone, you decide. The bearings should be replaced in axel sets, so if your left front is bad, you have to replace the right front too. While your at it, this is a good time to upgrade the lug studs and add spindle ducts.

aweil

Thanks for the info! I did swap jumper harnesses with no effect on performance.. the code stayed at the same wheel. I found one more post with some electrical troubleshooting info that I'm going to try before I replace the sensors/bearings.... it's for C1232, but I believe the procedure should be the same.

http://forums.corvetteforum.com/show...65&postcount=7

trussme

it could be your EBCM...so here ya go:

Electronic Brake Control Module
The EBCM sits between the engine and radiator. The EBCM is on the left with the large wire harness coming into it and the sticker on top. The Brake Pressure Modulator Valve (BPMV) in on the right with the brake lines coming out. The EBCM is a dry module, meaning that you can change it out without having to worry about bleeding the ABS system. All of the brake fluid is contained within the BPMV. The coils fit over small spools that have valves inside them. The valves are operated by an electromagnetic field supplied by the coils.
Start by doing a quick visual inspection of the wires. If there are any obvious signs of damage, you've likely found the problem. One member had a problem with the wires rubbing the serpentine belt.
Also check to make sure the wire harness has a good connection. If the connection appears solid disconnect it (see step 3 in the replacement instructions below) check the pins to ensure that they have not been bent or damaged in any way. If there is any sign of corrosion, clean it off. Once everything looks good, reseat the harness.


Next, let's move on to the grounds. The EBCM is grounded to the chassis on the left frame rail, just forward of the engine. It's the Black box right in the middle of the picture. As you can see, it's real easy for dirt and moisture to get in that area which isn't exactly good for electronic components. Even if you never drive your car in the rain, it'll still get wet when you wash it, and that could be enough
Start by unbolting the chassis ground, then take the chassis ground connector apart.
Corrosion that can build up in the ground connector. go ahead and clean it up with a wire brush before putting it back together. Also clean off the chassis and bolt to make sure you've got a good clean ground.

*If you are having any other electrical issues, it's a good idea to check the grounds.

At this point, we know all of the wires are good, but for some reason enough voltage is not getting to the system. It is possible that your battery is not functioning properly. If your battery is a couple of years old, has been drained and recharged a couple of times it might be a good idea to go ahead and replace your battery. This is a long shot for EBCM issues, but I think it's worth a shot before spending several hundred dollars for a new EBCM and you're going to have to replace it eventually anyways. Old batteries can cause a variety of minor electrical issues and you likely have a bunch of history codes for minor issues if the battery is causing the problem.


Now on the EBCM itself. If the electrical contacts inside the relay are dirty or burnt, the vibration from striking the module may change the symptoms or may clear them up for a while. This is by no means a fix or a cure all, in fact it could make it worse or it may not do anything, it's just something to try. Use a small plastic hammer or something similar, lightly tap the front of the EBCM on the lower right corner of the module. The area will be on the right hand side of the lower electrical connection seen in the picture below.
At this point, You've got to additional possibilities. Replace the EBCM or replace both the EBCM and the BPMV. The service manual calls for you to measure the resistance between each pump motor control circuit and the housing of the BPMV, if that checks our okay, you replace the EBCM if not you replace them both. Since most people do not have the equipment to do this the best we can do is to replace the EBCM. If that doesn't work, you'll have to go back and replace the BPMV.
The procedure for replacing the EBCM is very simple. The only special tool you need is a T-20 torx screw driver. I have a Craftsman tool set that has a 1/4" drive screwdriver with and adapter for many different size bit. Unfortunately, the adapter was to long to fit between the EBCM and water pump, so I purchased a set of Craftsman 5 pc. torx screwdriver set that worked fine. A flathead screwdriver may also be needed to pry apart the EBCM from the BPMV

1 - make sure the car is off.
2 - you will probably need to remove the airbridge to get to the EBCM.
3 - remove the wire harness by first removing the white plastic clip that locks it in place (I cut it off and replaced it with a zip-tie) (picture 1), then lift gray handle and pull back on the wire harness . At this point, you will be able to see the second wire connection that is removed by pulling down
4 - The service manual call for you the remove the 2 insulator nuts that hold the BPMV to the brackets and lift the EBCM/BPMV out of the bracket. I do not think this step is necessary because there is plenty of room while it is still in the bracket and you do not gain much additional clearance since the brake lines restrict the movement.
5 - Remove the 6 T-20 torx screws connecting the EBCM and BPMV - 1 on each corner and 2 on the sides
6 - "Separate the EBCM from the BPMV by gently pulling apart until separated" - I should start laughing here, but it's not that funny. It's been my experience that anytime the instructions call for you to do something gently, nothing gentle is going to work. In this case, I had to use a flathead screw driver to brake the seal. Once it moved a little, the rest was easy. In addition to the rubber seal, each of the 12 holes you see in picture 3 have a peg in them from the BPMV. Don't go crazy, but be prepared to force them apart.
7 - At this point, all you've got to do is put it all back together. push the new EBCM onto the BPMV.
8 - Replace the 6 T-20 torx screws
9 - reconnect the wire harness
10 - put the intake back on




At this point, the AH/TC/ABS should work normally. If not, you've also got a problem with the BPMV. Although you could replace the BPMV yourself, you have to bleed the ABS system which requires Tech II. For those of you like me that don't have access to Tech II, you've got 2 options. Replace the BPMV yourself and tow the car to a shop with Tech II to have it bled, or just take it in to have the BPMV replaced. The advantage is that you've already done all of the trouble shooting so you want have to pay the mechanic to diagnose the problem for you.



Replacement part sources

New EBCMs. Below is a list of part #s and estimated prices from Fred Beans to give you an idea of what you should pay.

Part Number: 10343433
All 2003-2004: $465.58

Part Number: 12216561
All 2002: $610.16

Part Number: 12208997
All 2001: $612.80

Part Number: 9367071
All 1999-2000 w/o Control Active Brakes: $486.40

An alternative to buying a new one is to have your original rebuilt.
For EBCM repair/replace

Call Brandon

877-648-7530 at ABS FIXER



or: www.absfixer.com



$150. plus UPS....warranted as long as You own it

Brawl623

I had a similiar problem...same code 1233, it happened at the very moment a strike of lighning hit the field near me as I was driving down the highway....anyways I went through all the grounds, checked the harness, swapped the wheel sensor/hub/bearing assembly all to no avail, until I replaced my EBTCM with a refurbished one at absfixer, then problem solved. I was under the impression my old unit could not be repaired because it wasn't throwing the typical 1214 code, so I bought a refurbished unit. Now that is to be determined because I will be sending my bad unit to absfixer and they are going to dissect it to see if it can possibly be fixed. Anyways, hope this helps.

journalman

As I just posted in another area, my '99 has been babied, garaged, only 11,000 miles, no modifications, etc. So when I got at the same time both 1232 and 1233 codes (LF and RF wheel speed circuit open or shorted), one would think this would narrrow the problem down to a few first things to try? Any suggestions? Thanks!

aweil

Ever since this: http://forums.corvetteforum.com/show....php?t=1838092

I addressed the drain issue and haven't seen the TCS code since.

lucky131969

The service manual has a complete troubleshooting section for this DIC code. You can check the wheel sensor output to make sure it's bad before you change it.

O'reano

I had the same problem. I discovered it was the weak connection coming from the wheel speed sensor, in the harness. I took mine apart. I cleaned them, and tightened them up. I then strengthened the connection with tape and a 4" little rod. I have not had issues since. The permanent fix would be just to cut the harness and solder the wires together, then making it weather proof.