Vehicle service information is jam-packed with acronyms, and keeping track of what they all mean can be a full-time job. The definition of an MPA switch might not come immediately to mind but follow this Cadillac Escalade Real Fix to see how it relates to diagnosing and repairing a code C0286.
Vehicle
2002 Cadillac Escalade 6.0
Title
C0286, Replaced Brake Pressure Modulator Valve
Complaint
The customer states the anti-lock brake system (ABS) light is on.
Cause
Connected a scan tool and found code C0286 – MPA Switch Remains Closed, Open Or MPA Intermittent. Used the scan tool to clear the codes, performed an anti-lock brake system function test with the scan tool and found the code reset. Used the scan tool to monitor live data and found the medium pressure accumulator (MPA) switch parameter indicated “Uncharged”. With the key on, engine off, used the scan tool to monitor live data, connected a fused jumper wire across the MPA switch harness connector signal circuit and supply circuit and observed the MPA switch parameter changed state to “Charged”. Removed the MPA switch from the brake pressure modulator valve and reconnected the MPA switch. With the key on, engine off, used the scan tool to monitor live data, depressed the MPA switch plunger and found the MPA switch parameter indicated “Charged”. These test results verified the brake pressure modulator valve was faulty.
Correction
Replaced the brake pressure modulator valve, cleared codes, and verified the vehicle operated properly. The customer’s concern did not return.
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