Help! code 1248 and c1254

[Big bat]

My 2003 stalled one day. a few days later would not start. It came down to low voltage from ignition switch. Clean up contacts worked fine, how ever the traction display and service engine soon could not be deleted even with a scanner. The code that comes up is C1248 and C1254. What can be the causes for the C1254? I had replaced the ignition switch, the scanner still will not clear the codes and remove the traction service soon display, also what is the steppes to use the on board scanner? Thank You

 

[Toms007]

First off, a "Welcome to CAC" is in order. The next thing I'll say is, The C5 is very dependent on good electrical power. The first thing I would do, is have the battery checked and make certain that it meets ALL the specs. Watch the videos from here to see what the specs are.....now, Part numbers have changed since the videos were done, but the specs are the important thing here.

C5 Column Lock debunked

 

[Hib Halverson]

DTC C1248 is a fault with the "dynamic brake proportioning" part of the ABS.

DRP takes the place of mechanical proportioning in the base brake system. This fault turns on the red brake warning light and there will be no brake proportioning when it exists.

DTC C1254 is a fault in the EBCM relating to the check sum process the EBCM goes though during a self test. The microprocessor in the EBCM periodically checksums those areas of memory that hold critical operation data. The microprocessor also checksums these memory locations when ever new data is written to them. The process is called a "running checksum". To check the keep alive memory the processor compares the periodic checksum to the running checksum. If they do not match, the microprocessor sets DTC 1254.

When C1254 is current, the service ABS, service traction control and service active handing lights will be on. Also when this code sets, C1248 also sets and the red brake warning light comes on.

1254 is a serious fault as, when it's current, you have no DRP, ABS, TCS, SES and the variable rate steering feature is disabled. Also the EBCM can't send serial data.

In most cases, solving this code is not a DIY task as it requires a dealer-grade scan tester and the ABS breakout box. This code can be caused by no start conditions, low battery, battery disconnection, battery replacement or bad ground connections at the EBCM or poor connections at the EBCM harness connector.

You can't erase it with your scanner because either 1) your scanner does not support the EBCM, which many consumer grade testers do not or 2) the codes are current, i.e.: the faults still exist.

If you are going to try to fix this yourself, the first thing to do is check the two EBCM grounds. If they have high resistance, fix that and try clearing codes. If the code(s) still exist, you need the factory service manual or a subscription to GMSi from ACDelco. You also need access to a scanner which supports EBCM codes and maybe even the breakout box.