P071

DTC PO71:

IAT, MAP And TPS Circuits:

Weather Effect Chart:

CIRCUIT DESCRIPTION
This diagnostic test monitors Throttle Position (TP) sensor, Engine Speed (rpm), Manifold Absolute Pressure (MAP), EGR Flow, and Air Conditioning (A/C) Clutch status. Engine operation requires that a large change in manifold pressure must be preceded by a change in engine load due to changes in throttle angle, engine rpm, EGR flow or A/C clutch status. If TP sensor, engine rpm, EGR Flow, and A/C Clutch remain constant, and there is a rapid change in MAP, Powertrain Control Module (PCM) Diagnostic Trouble Code (DTC) P071 will set.

TEST CONDITIONS
1. Code P021 and P022 not set.
2. TP sensor does NOT change more than 1 degree for 1.01 seconds.
3. Engine Speed is greater than 500 rpm and does not change more than 100 rpm for 1.01 seconds.
4. EGR does NOT change more than 4% for 1.01 seconds.
5. Air conditioning clutch must stay "ON" or "OFF" during test (cannot cycle).
6. Low coolant level and engine overheat not present.
7. Traction control not active.
8. PCM receiving reference pulses from Ignition Control Module (ICM) at least every 0.3 seconds.

FAILURE CONDITION
MAP sensor reading changes more than 6.3 kPa in 12.5 milliseconds.

ACTION TAKEN
PCM uses a substitute MAP value based on engine rpm and TP switch status.

NOTES ON FAULT TREE
1. Checking if the MAP sensor can read barometric pressure correctly (85 to 105 kPa).
2. Checking the MAP sensor ability to react to a known vacuum (26 to 34 kPa).
3. Checking the MAP sensor's ability to react to a sudden change in vacuum.