Greg Ochs

I have had this problem with my wifes 98 C5 now for going on 6 months. I have worked on it on and off as my electronics service job permits since I travel for work. I followed the advise on the forum about checking and cleaning the ground connections as well as other suggestions. Nothing seemed to make a difference until I ran across the thread about a member who was clearing the code while driving and then slamming on the brakes to activate the ABS. I know when the car is started the system turns the ABS pump on and off and if the voltage readback is not high enough the code C 1243 is set and you get the messages. Since I do not have the interface connector for the EBCM I pulled the module away from the pump section. I measured the resistance of the pump motor from pin number 8 ((from left to right) (it is the first pin on the right hand connector))to the frame ground and it was in spec according to the manual. In my job we also use different size pumps for pressure and vaccum. When a pump is new or has been rebuilt it requires some break in period. If a pump has been used and off for some period of time it will also draw more current due to sediment build up and not being exercised. With this in mind I pushed a wire into pin 8 and ran it over close to the positve post of the battery so I could exercise the pump manualy. The pump came on the first time I touched the positive post but sounded sluggish. I exercised the pump about 6 more times for about 15 to 20 seconds at a time. I put the EBCM back on the pump section cleared the codes and so far the car has been running for one week now with only one message the first day after this procedure that message cleared on the next start by itself. If you try this use a heavy gauge wire and be aware the wire may get warm as you touch the battery. The pumps on these ABS units are most likely not broken in since they hardly run durring the life of the car. 3/23/08 The car has been running fine with no more Traction control codes or Service ABS messages now for three weeks. If I can be of any help to other members experiencing this nightmare drop me a line or a reply. 4/11/08 The car has been running grreat with no problems now for six weeks. 10/9/08 Just a quick update that the wife's car is still running great with no 1243 codes.

FASST LN

Subscribed. :o

BlackZ06

EXCELLENT information ..... GREAT post .....

Thank you.

rkort

this could be a break through for this problem, and a money saver.
great post

rkort

oh forgot could you do picture on the orientation of which pin to hit with the 12volts, i would be worry to hit the wrong pin and fry something
thanks

Bill Curlee

Fortunately for me,,,,I drive my car hard enough to make that pump work! I know most people don't. I have recommended to a few people to find a open parking lot or deserted stretch of road on a wet day and run it up to 40 mph and break HARD enough to lock the tires and make the pump run. That will sometimes clear up a few problems caused by sluggish motors.

VERY GOOD WORK! I find it very helpful to show pictures of the procedures that your doing. If people can see pictures of the procedure, they will be a LOT more comfortable doing it.

Bill C

Bill Dearborn

I too use my ABS quite frequently plus I change my brake fluid 4 or 5 times a year. A lot of cars don't ever get their brake fluid changed and when it gets sludgy after a number of years it could affect the pump and thus the pump motor as well.

Bill

CraZee ZO6

yea oddly I just got this today.
i thought because I had my spare wheel on because I got a flat the other day. so im running 3 19 and 1 17 oem wheel.


how do i clear the codes? I ordered a 19 tire to go back onto my wheel so I can have 19s all around agian and hopefully not cause this problem?

FASST LN

CraEZO6, make sure you have that 17 inch wheel on the front. Having two different sized wheels on the back will wear out your differential, I would think.

Bill Dearborn, oddly enough I began having this problem after I changed my brake fluid. For a while I thought maybe I had air in the lines. But I've bled it several times since then and the problem still persists...plus some of the other people with this same problem have never bled their brakes (so air would not be the problem - but possibly sludge like you said).

Greg Ochs

Bill my profile says that I am not allowed to post attachments. I have some pics out of the manual to post, can you help?

Greg

Bill Curlee

Greg

Send me the pictures via e-mail. I will post them for you. Look in your PM box for my e-mail addy.

BC

BC

rkort

just an update, i took all my stuff to my mechanic friend, to get my car work on. i also took him the post form ochs and ask him to try this before we change out the ecbm or the other pump that i bought. well he did it and it took a lot to touchs, but it work the motor free up and seem to be working. however on the way home i hit the brake hard and it through the p1243 code again, but i was able to reset it this time. i will let you know what happen in the next few weeks. well i drove it over the weekend and it through the code again, this time i have had no luck in getting the code to go away, i think i will have to change my pump, and this will have to wait until i have some more funds to throw at this problem.

RED LT4

Do you get any other codes since you are running 19"....I am running 19" all the way around and I started getting codes on that too! That set a traction code

RED LT4

Do you get any other codes since you are running 19"....I am running 19" all the way around and I started getting codes on that too! That set a traction code

BlackZ06

What code(s) is/are being set ????

The EBCM is programmed to expect a tire "stagger" .... the fronts should be smaller in diameter than the rear tires. Without this stagger Traction Control may trigger at some speed. Generrally you should not be getting a code just because you are running the same size tires on all four wheels.

FASST LN

I'm doing the above ABS procedure right now. I've taken a couple of pictures to help others figure out which one is the correct #8 pin that I'll post later. However, the pins' numbers are stamped above them, so it makes it pretty easy. Apparently there are a total of 14 pins, 7 on one side and 7 more on the other side.

Also, the wire I'm using gets very hot, very quickly. The wire is from a volt meter.

Gosh I hope this works....

Tourmgr1

An alternative to exercising the module yourself is to take it to the dealer and ask them to use a Tech 2 to perform this task. No need to remove any parts as they use the diagnostic tool.
My local dealer fixed mine.......... Thanks Cauley Chevrolet.
Good Luck.

FASST LN

Well, I don't want to get my hopes up too high, but for the initial drive my car never through the 1243 code and my ABS/TCS worked fine...something it hasn't done in over a year.

I took a few pictures that I'll post in a minute of the EBCTM, where the screws are located that need loosening before removal, and which pin is the magical #8.

Tourmgr1, you are right. And if someone will do that for free for you, then its worthwhile. I didn't want to get charged a $90 diagnostic fee plus any additional 'labor' time when I could do it myself.
Glad that you mentioned that alternative as there are many people who don't have the tools or physically can't work on their own car.

Thanks!

FASST LN

Okay, here are a few pictures I took while doing this to help others understand what Ochs is describing here.



The first picture is of the BPMV after I'd removed the EBTCM, which for me was located between the engine and the radiator, just under the upper radiator hose (see the white arrow pointing to the rectangle). In the below picture, I had removed the upper radiator hose (drained the coolant first) and the air bridge and intake.




To free the EBTCM (before prying it apart from the BPMV) you must remove the 4 screws (that have torx heads) from each corner and a fifth bolt/screw that also has a torx head on the bottom-center. It was a real pain to access all of these screws. See the arrows in the picture below:




Once I removed and inspected the EBTCM, I notice the seal was broken (not sure if I did that when I removed it or not) and something appeared to have leaked onto the circuit board (note the liquid stains and the broken seal in the upper-right corner).


Below, the arrow is pointing to the #8 pin that activates the ABS pump. Note that the #7 (left side) and the #8 (right side) pins stick out further and are larger than the other 12 pins on the BPMV.



The last picture is of me trying to show how I inserted a wire into the #8 pin to activate the ABS pump (while the other end of the wire was connected to the positive battery terminal). The wire does get hot while doing this, so don't do it for very long.

FASST LN

When I started the car this morning, everything was good...but as I backed out of my driveway, the usual ABS/TCS failure lights came on.

I checked the codes, of which there were many. I tried clearing them and amazingly they all cleared and didn't come back for the rest of my 20 mile commute into work.

We'll see how driving home today holds up.