Since my last issue (ignition switch), I have begun to experience a 28 tcs c1233 h code. I know the "h" stands for historical, but I can clear the code, and drive until 25mph, then the code and abs/ traction light come back on with it. I immediately pull codes thru dic, and it shows this 1233h code. Why would a current code show as history?? It's current enough to trigger the warning lights...so why no "c" designation? If I slow down under 25, I can clear the 1233h code, and the warning light will go away, when I accelerate past 25mph, it comes right back. I have ohmed and volt tested both front speed sensors, verified continuity in both side harnesses, and swapped sides with the jumper. Both sensors "appear" to be good. Im assuming next step would be to pull abs module plug and check for continuity to certain pins? Could someone help to guide me as to which pins I need to check? I just went through all this a week ago for a faulty ignition, so I'm mostly familiar with locations of grounds and plugs. My car is a 2003 z06 btw.

 

https://www.corvetteforum.com/forums...ce-please.html

 

so according to this, it may be my ebcm module itself? I didn't think brandon at abs fixer could repair a 1233 code? Or am I misunderstanding the issue?

 

I was just trying to give a link to one recent thread regarding the same problem. I thought the factory troubleshooting would be helpful. Very remote that you have a bad EBCM for on wheel sensor code. Sorry for the confusion.

 

no worries! I still have a couple more tests to run from the ebcm back to the wheel sensor per an old bill curlee post. I have the correct ohms, i have voltage when i spin the hub, so i believe sensor is good. I ohm out harness for continuity on both pins. I wiggled everything i could reach with my son in law watching the ohm readings, and dont seem to have a short. I will probably call brandon at abs fixer Monday, and see what he says. I have had zero issues with this car until about 2 weeks ago. Initially it looked like the Ignition switch cured everything, but no dice. I did cure 7 different codes I had going on tho..

 

so far, today, I have checked the harness at sensor for the 5v bias signal, and got 5.06v with key on (grounded to battery ground). I have not yet been able to get my 12v test light to light up by putting 1 leg on battery positive, and the othe leg on the black wire in the harness connector as suggested in another thread. I have cleaned the ebcm grounds last week during my faulty ignition issues, so they should be good. Im going to continue to try to establish whether or not I have a bad ground wire. Does anyone have a pinout diagram of the ebcm connector to aid me in checking ground wire continuity between harness connector and ebcm plug? Any help is appreciated!

 

ok, so being as that there is very little interaction here, I will continue to post what I've done in hopes of helping others with this issue. I tested between the sensor end of harness (white wire)to pin ten to and have continuity. Tested from black wire to pin 24 on ebcm plug, and had continuity also. Then cleaned (checked for bent pins also) ebcm plug (both male and female sides) and plugged back in. Was able to establish 5.06v by placing one test lead of voltmeter in each plug terminal. Tried the test light but it did not light up by placing it on positive battery post and black wire from harness. One poster said it would light up using ebcm grounds as ground. It didn't. Im unsure of this test because everything else i did indicated a perfectly fine ground wire. I realize the 12v puts a load on the ground, and maybe that is the issue. I could use some advice at this point on whether my procedures have been faulty, or have I missed something? I have also performed wiggle test in each step of this procedure. My conclusion at this point is that the hub and wheel speed sensor have to be the culprit of my 1233 code. Wheel bearing does not shake up or down or side to side, and sensor checks out. It produces voltage when spun, and ohms out between pins at just over 1100 ohms.

 

I'm having a similar issue with a rear ABS sensor. After a whopper of a pot hole I've had problems with one of my rear abs sensors. I figured it was the wiring but haven't had any luck cleaning the connectors like usual. I'm thinking it may be the wiring connection inside hub so I'm replacing both rear hubs (it's time). I was chasing an identical problem up front and it wasn't the wiring connectors it was the wire as it went into the sensor. The insulation was the only thing holding it together. The wire inside had broken and only made contact at certain angles. I found this out when I changed the hub for a different reason.

 

I've performed wiggle test, and swapped sides on jumpers, no difference. Code stayed on same wheel. All i can do now, i think, is replace hub that doesnt seem bad. After that, its new ebcm if hub doesn't work. Im wondering if signal is breaking down at 25mph.

 

LONG UPDATE: after my initial issues that turned out to be the ignition switch, I encountered a 1233 code that would not go away. I tested everything to no avail. Bill reached out to me, and we spoke in length about the tests I had done, and steps I had performed so far trying to track down the cause of the wheel sensor code. Hub had zero play, speed sensor hit all the correct numbers in testing. All wiring read correctly when tested all the way to the ebcm plug. I located a pinout diagram, and tested all pertinent wires. Everything performed flawlessly, wiggle test was perfect also. I came to the conclusion (after speaking with Bill) that the ebcm was throwing the code. I contacted mercer corvette for a lifetime warrantied ebcm replacement. The speed sensitive 1233 code cannot be repaired (validated info with Brandon at ABSFIXER.) Brandon did not have one in stock, so he put me in touch with Mercer Corvette. 3 weeks later, my newly rebuilt and warrantied unit showed up. 30 minutes later it was installed and all lights on dash are gone!! As an added bonus, since I replaced my ignition switch i havent started the car in the 3+ weeks since (last startup was June 22nd). The car started just fine after all that time!!!! Before, if it sat for 1 to 2 weeks it would be dead, I believe the ignition switch was allowing power to flow thru it even with the key off and out. Anyway, my pristine 2003 with 70k on the clock is back up and running flawlessly!!!