MAK

My EBCM went out several months ago and I have just been driving my 02 Z06 without the ABS, Traction Control, or Active Handling. Those were the indicated codes and what showed up on the display each time I started the car. I mistakenly thought that I would just be driving with those options turned off. All was fine until a couple weeks ago when I was going down the highway and had to hit the brakes. Not a panic stop. I was way behind a group of cars in front of me but I saw them slamming on the brakes and so I pressed mine. That’s when the Active Handling decided to kick in I guess, and locked down one front brake and sent me in to the other lane. Then in a fraction of a second while I’m trying to correct (I’m sideways in the other lane) the other side locked down and sent me nearly 180 degrees the other direction. Barely kept it from going off the embankment and fortunately nobody was coming toward me in the other lane…
Used EBCM (and supposedly working when pulled) from a 03 Z06 arrived and I installed last night. Most previous codes do not reappear after a reset on the DIC, but one remains and one is new. When ignition is activated I get warnings for Service Vehicle Now (this one had not been seen in the past except right after the near disaster a couple weeks back), and Service Active Handling.
The 28TCS codes are:
C1284 HC Lateral Accelerometer Circuit
C1285 also appeared once after I had cleared everything but has not reappeared
C1287 HC Steering Position Sensor Circuit
C1288 also showed once after I had cleared everything but has since not reappeared.
These codes were not ones I had been getting prior to the incident a couple weeks back.
I already did a lot of reading on these last night but am looking for some further suggestions and input before I spend time going the wrong direction. I haven’t had time yet to go through and check/clean all the grounds or break out the multimeter and start trying to get readings as some of the related message threads explain.
My first main question is could these codes still be due to a problem with the EBCM I just installed or would I have to be getting other codes if there was still an issue with the EBCM?
Did I miss somewhere in my reading about a way to “reset” the Accelerometer or Steering Position Sensor? Like pulling a fuse or disconnecting the battery, etc? Or do I need to get it out on the road and make some maneuvers first? I recall seeing a thread about doing figure eights in a parking lot and something about needing to drive straight for a certain distance.
If it is the Steering Sensor, what is my best source at this stage since it’s no longer available from GM?
Thanks for any help and suggestions.

dadaroo

Not at home with my FSMs to help you with the details. Not sure if you got a good used EBCM or not.

We need to know what codes you had before you replaced the EBCM. I know you say these codes are all new but the old info may help us.

Checking the EBCM connector for good terminals/pins with no bends, corrosion, etc would be good also. These new codes popping up tends to make me think it is related to the EBCM or installation.

Also, some EBCM related codes will NOT show if you pull them after you turn the ignition OFF. Can't explain why, I got that from Bill Curlee. Bill correct me if that statement if not true. I expect/hope he will weigh in on this. If not send him a PM and a link to this to see if he will help also.

Sometimes disconnecting the battery for a few minutes and reconnecting has solved some weird issues and it is free. Can't hurt.

The SWPS for your year is available all day long. I ordered one a couple of months ago to just put in my inventory of spare parts. The earlier car SWP sensors are ones you can't get NOS. If you need one later contact Gene at Cultrag.com, he is a Forum vendor here.

Mr. Sam

MAK

Glad to hear I can at least still get a new steering sensor.
I'll have to post up my old codes tonight when I get home. I wrote them down somewhere.
Sounds like the lateral accelerometer is an easy swap so I guess that will be the first part I try replacing once I can get some voltage reading (if I can figure that part out).
Thanks for the info so far.
Update:
Drove it a few miles when I got home. Same warnings and error codes remain and another has reappeared: C1288 so now I have C1284, C1287 and C1288
Codes I pulled prior to replacing the EBCM were:
C1214 Sol Valve Relay Contact or Coil CKT Open
C1225 RF Excessive Wheel Speed Variation
C1226 LF Excessive Wheel Speed Variation
C1233 RF Wheel Speed Circuit Open or Shorted
C1248 Low brake fluid?
C1283 Excessive Time to Center Steering
C1288 Steering wheel sensor

U1160 Loss of Communications with LDCM
U1064 Loss of Communication with IPC
U1096 Loss of Communications with IPC

racebum

codes aren't always accurate and have not been since GM abs had codes. years back i troubleshot a c4 with an abs sensor code, replaced sensor, still had code, long story short, bad ebcm. they can be damaged by voltage spikes apparently.

when you have extra codes come up with this other ebcm that you did not have before that alone is suspect. i would try and get a known good ebcm from either a reputable wrecking yard like vette nuts or borrow a friends from a car that is trouble free

many people who sell used parts are liars. 100k mile parts are sold as 10k and half functioning parts are sold as good. same with untested. the introduction of moisture can also cause all kinds of weirdness with the abs system

dadaroo

It is "too" strange that you replace the EBCM and you get rid of the old codes and you get two new C codes.

If it were me, I would send the EBCM to a good ABS shop and provide them the codes you are now getting with it and see what they say.

MAK

I just went ahead and ordered a new lateral accelerometer. That's an easy swap to see if it resolves the one error code and cost wasn't too bad. If that doesn't fix I'll know to focus back on the EBCM. Wasn't going to have time to do any more troubleshooting until later next week and didn't want to the. Have to wait another week for the part. Hopefully that is the fix although I don't look forward to having to replace the steering wheel sensor.
Thanks all for the responses. I'll post back when I know more.

MAK

This now getting pretty frustrating. Pulled the seat and carpet out and swapped the accelerometer with a brand new one and still get the C1284 error code. At this point I wish I just had a reliable way to turn off the active handling and be assured it would not kick in again at an inopportune moment. To make matters worse I jumped the gun and ordered the steering wheel position sensor too.
I unfortunately don't have anyone I can swap a known working EBCM with. I guess I'll try calling ABS Fixer tomorrow.
Does anyone know for sure if a bad EBCM can also cause the 1284, 1287 & 1288 error codes?

dadaroo

If you are concerned about the AH activating again just pull the 2 EBCM fuses. You will just have normal manual braking functions without electronics.

Should be 5 and 52 in the engine fuse box. You can double check your box or OM.

How many parts are you going to throw at this "used" EBCM before you have it tested?

MAK

I just spoke with Brandon at ABS Fixer. Very nice guy and extremely helpful BTW. He recommended that I go ahead and install the steering wheel sensor when it arrives. He said that often the steering wheel sensor will also cause the lateral accelerometer error code since they are on the same wire. He said in his experience that when he has tested EBCMs for cars that were throwing the 1284, 1287, 1288 errors, that the problem was due to the sensors, not the EBCM.
So, I'm going to go ahead and replace the steering wheel sensor next and if that doesn't clear it up I will be sending him the EBCM for testing. Hopefully the new sensor will take care of this. I was just bummed out when the new accelerometer didn't remove the 1284 code but he said that is not uncommon so I feel a little better.
Hopefully this is not a nicked wire somewhere. That will be a real PITA to run down.
Thanks again for the help and responses so far.
I took some pics of the lateral accelerometer and location if anyone is interested. I wasn't real sure where it was until I got the seat and carpet out...

MAK

It may come to that.... Thank you

SoAlVette

"QUOTE" That’s when the Active Handling decided to kick in I guess, and locked down one front brake and sent me in to the other lane. Then in a fraction of a second while I’m trying to correct (I’m sideways in the other lane) the other side locked down and sent me nearly 180 degrees the other direction. Barely kept it from going off the embankment and fortunately nobody was coming toward me in the other lane…

Man, that's some scary s*&%!!!!!!!!!

If ever there was a case for GM to be more involved in the EBCM issues, I would say that is it. I wonder how many accidents have been caused by this, especially in the pre 2001 cars since the EBCM cannot be repaired and are sparsely available?

So, I guess to be safe if the EBCM goes out, pull the fuses until it is repaired or replaced.

dadaroo

Do you need any DIY info to replace the SWPS?

MAK

This thread below was full of great info and pics so I think I am good to go and ready to commence cussing and throwing things once the part arrives.
If you had any other suggestions though I'm all ears.
Thanks again.
https://www.corvetteforum.com/forums...-sensor-2.html

dadaroo

Here is one you might review.

http://www.ddisoftware.com/c5-procs/

MAK

Yeah, tell me about it.

MAK

Thanks bud. Appreciate the help.

MAK

Well, finally got the steering wheel sensor replaced and still have the damn 1284 and 1287 codes. Guess I will have to take the EBCM out again and send it off to be tested. I was sure hoping this would have fixed it based on what Brandon had said. Never can be that easy can it?

MAK

Well, it's official, after they ran it through the tests and tried in another car. My used "confirmed functioning when removed" EBCM is bad and can't be repaired They unfortunately don't have any repaired ones for sale and the waiting list is long. I guess I'll put it back on to keep everything weatherproof and pull the active handling fuses. Times like this really makes me appreciate my stable of old no computer vehicles...

dadaroo

You can still buy new EBCMs for your year. The P/N should be 12216561 from my parts info, but you can verify. 2001 and 2002 should be the same.

73Corvette

Brandon vs dadaroo MMmmm I would take dadaroo every time. OVER any GM tech with electronics...
He may not be perfect but, he is seldom wrong... listen...LISTEN to him.
I know it's not a contest and you just want your damn car fixed but trust me...he knows what he's talking about and will get you fixed in the most effective, less costly way possible...