Test Notes

SIGNAL FUNCTIONS
The Manifold Absolute Pressure (MAP) sensor is a variable capacitance sensor that when supplied with a 5-volt reference signal from the Powertrain Control Module (PCM) produces a digital frequency signal that indicates pressure.

Smoke Control - The MAP signal is used to control smoke by limiting fuel quantity during acceleration until a specified boost pressure is obtained.

Dynamic Injection Timing - Optimizes injection timing for boost pressure measured.

Test Schematic:

MAP BP Tester Hook-up:

FAULT DETECTION/MANAGEMENT
A MAP signal that is detected by the PCM to be out of range or at an incorrect value for specific conditions will cause the PCM to ignore the MAP signal and operate the engine from an inferred boost pressure signal.





Connector Checks To Ground (B-)
Check with sensor connector disconnected and ignition key and all accessories OFF.





Connector Voltage Checks
Check with sensor disconnected and ignition key ON.





Harness Resistance Checks
Check with Breakout Box installed on engine harness harness only.





Operational Signal Checks
Check with Breakout Box installed in line with the PCM.

NOTE: After removing connectors always check for damaged pins, corrosion, loose terminals, etc..

MAP Sensor Pressure/Frequency Chart:

DTC DESCRIPTION

Circuit Concerns:
126 = Signal frequency was greater than 270 or less than 80 Hz for more than 0.10 seconds.
127 = MAP in-range concern (inactive for 0.25 seconds)

System Concerns:
128 = Detected high boost signal at low idle (restricted MAP sensor inlet)