C0285 relates to a pressure fault, or incorrect indication of one, from a component called the medium pressue accumulator switch. It is attached to the brake pressure modulator valve. There is a service bulletin on this that came out in 2004, here is a copy of it.
#04-05-25-008: ABS Light On, Service Stability System Message Displayed, Stability System Disabled Indicator On, DTCs C0285 and C0286 (Install New Medium Pressure Accumulator Switch) - (Aug 6, 2004)
Subject: ABS Light On, Service Stability System Message Displayed, Stability System Disabled Indicator On, DTCs C0285 and C0286 (Install New Medium Pressure Accumulator Switch)
Models: 2002 Cadillac Escalade, Escalade EXT
with Vehicle Stability Enhancement System (VSES) (RPO JL4)
Some customers may comment on the Antilock Brake System (ABS) light coming on. Others may comment on the Service Stability Message Displayed and/or the Stability System Disabled Indicator being on. Technicians may find Diagnostic Trouble Codes (DTCs) C0285 and/or C0286.
Technicians are to install a new medium pressure accumulator (MPA) switch. The new switch, P/N 88983914, is grey in color. The previous switch, P/N 12545898, is black in color and will not fix this concern.
If it has the above mentioned black switch, I would correct the situation by replacing it. If the code returns, you will most likely need the brake pressure modulator valve. Here is an illustration of the unit, it doesn't show it located in it's natural environment. The BPMV is mounted to the inside of the left frame rail, forward of he fuel tank. The switch in question is the one diagonal from the reference #1.
February, 1, 2013 AT 2:16 AM
I am having the exact issue with my 2002 Cadillac Escalade 6.0 AWD 150, xxx miles (" Service Stability Light light comes on after driving my vehicle for 30 seconds. It is preceding by a grrrrr (BPMV Pump) noise which lasts around 5 seconds") with the exception of the DTC codes. The scanner found the following codes: C0212- Yaw Rate Sensor Circuit
C0286- MPA Switch Circuit
C0290- Lost Communication With PCM
C0298- Powertrain Indicated Traction Control Malfunction
It is my opinion (could be wrong. Usually am) that since all of the codes present share the same piece of equipment from which they originated, I would find the "common denominator", which in this case would be the EBCM, correct? Please help me with this issue as soon as possible so as it may be resolved.
March, 27, 2014 AT 6:35 PM
Im not a mechanic but I have a 2002 cadillac escalade with the check stability light on, I changed the switch only to find out there is an updated one available, I changed that too. Then I changed the electronic control module only to have the light still on. It now says the brake pressure modulator valve is bad. I love my truck but after $4300, ive had enough. OMG!
April, 11, 2014 AT 11:26 AM
Has anyone had similar problems? Does this ever end?