My 2003 C5 is throwing C1293 DTC (and giving "Service Active Handling" warning on dash, and limiting speed to ~55 until I turn active handling switch off). I had some rodent damage to the wires going to the brake pressure sensor. I've repaired and double checked continuity to the EBCM and for shorts. Does anyone have an idea of the range of the output voltage from the Brake Fluid Pressure sensor on the EBCM module? It can be read from a TECH2 in the VSES section. With car not running but ignition on, TECH2 is telling me it is 4.41V and when I apply the brake, it stays there. Tomorrow I'm going to put a voltmeter on the wire from the sensor to see if the voltage is actually what the EBCM says. The rascal also chewed up the wires going to the FL ride height sensor. I fixed the wiring but the sensor got fried when the wires were shorted. Hope it is not the same for this one...

It would beget if you have that info, or if you have a Tech2 and a C5 if you could check it for me with and without the brakes depressed... Thanks!

 

With the sensor unplugged and key on you should see 5 volts on the ORANGE wire...that 5 volt reference is shared with the Lateral Accelerometer, Yaw Rate Sensor, and the Steering Wheel Position Sensor.as you can see in the wiring diagram...to check signal wire integrity you can jump the 5 volt reference to the signal wire which is the BLACK wire...the voltage you are reading on the Tech 2 is the signal voltage...you should now see 5 volts on the Tech 2 sensor voltage data PID...you can also put a T pin or something similar into the signal wire terminal and take your one finger and put it on the T pin and your other finger on the Alternator B+...you probably won't see 5 volts maybe 3-4 volts depending on your body's internal resistance...the safest way to test is with the T pin should the signal wire be shorted to ground OR using a 5000 ohm resistor in place of the jumper...this will test the signal wire from the sensor to the EBCM...you should see less than 100 millivolts (0.1 volt) on the Low Reference Ground (GRAY wire) key ON or with a test light connected to B+ the test light should illuminate…the BPPS is like any simple 3 wire potentiometer…5 volt reference, signal, and ground...if the wiring checks out good you need a new sensor so don't buy one off Ebay or Amazon....and as you can see there are splices on the 5 volt reference circuit...S108 and S310....BTW, how did you check for "shorts" ??

 

 

Tech2 is useless without a service manual. They are cheap....get one.

 

Thanks! I think you have led me to the issue. You mentioned the Orange wire being the 5 volt reference and the Grey as the Low reference. When I tested with the Fluke DVM, I was seeing -5.04 volts. Looking at the schematic, I see what's going on. The mouse completely destroyed the connector in the middle that sits on the frame (C152 on schematic). So when I repaired (and eliminated that connector), I naturally connected orange to orange, grey to grey, and black to black. but if you look at the schematic, they swap orange and grey at connector C152! Someone must have goofed making the original harness!

I'm off to see if the EBCM is happier with the readings it gets now!

Thanks so much. Stay tuned...

 

That was it! Finally after months no more "Service Active Handling" or C1293. Also on the Tech2 once I swapped the wires, the brake fluid pressure was nominally at about 0.6 volts, and went up to 0.9 volts when I depressed the brake pedal (ignition on, engine not running). Previously it was sitting at 4.41 v and didn't move at all when brake was pressed.

Thanks again!

 

Interesting. According to the service manual, the brake pressure input parameter is supposed to read between .14 and 4.9v.....with the ignition on...engine off. The test does not call for depressing the brake pedal.

 

0.6 V falls between .14 and 4.9 so all is good. Drove for 2 hours more, great to have no warnings on the dash. A few pics of the damage from a week out of the garage. Had to drop the front suspension to fix the other damage between the composite spring and engine. Somehow it chewed just the 3 wires going to the left front ride height sensor out of a large bundle of wires.

Pressure sensor

wires between spring and block

All this for 3 wires!

 

That dude really went to town on that wiring. Did you get him?

 

Him and all is friends... That engine looks great!

 

 

I hate mice!! BTW, don't spend $$$ on a mouseblocker, because they don't work. Trust me. If I weren't gone 6 months of the year, I'd have 2 or 3 furry, 4 legged mouse blockers, lol!!