Chassis, generic

C063F Brake Pressure Sensor J Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

The signal of brake pressure sensor J is stuck below its lower limit. Ipgate's double-stroke-piston patent fits one pressure sensor to each brake circuit and checks the delivered fluid volume against the pressure-volume curve of that circuit; such a circuit sensor is one possible J position, though no manufacturer confirms the letter. Denso defines 0–0.3 V as the low fault band and notes that a broken feed or signal line also lands there when the input has a pull-down. Saab/GM detects a ground short or open on the signal or 5 V reference after 0.1 s and then turns off ABS, traction and stability control for the rest of the ignition cycle. Usual suspects: a chafed signal wire, a shorted reference, a failed sensor element.

Likely causes

Chafed signal wire touching ground
5 V reference shorted to ground
Broken feed or signal wire pulled to 0 V by the module input
Failed sensing element in sensor J

Symptoms

  • ABS, traction and stability warning lamps on
  • ABS and ESC inoperative until the next ignition cycle

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–1,600
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

brake pressure sensor jsensor wiring

Related codes

C063DC063EC0640C063BC0643

References: patents.google.com, patents.google.com, saabwisonline.com.