The MAP sensor is supplied with a 5 V reference voltage at Pin 2 from ECM Pin X1–14. The MAP sensor is grounded at Pin 1 from ECM Pin X1–6. The MAP sensor returns a variable voltage signal from Pin 3 to ECM Pin X2–3.
Fault Detection / Management
The ECM will ignore the MAP signal when the signal is detected to be out of range or an incorrect value is
read. The engine will continue to operate based on estimated values.
MAP Diagnostic Trouble Codes (DTCs)
DTCs are read using the EST or by counting the flashes from the amber and red ENGINE lamp.
DTC 121
Intake MAP signal out-of-range high
• DTC 121 is set by the ECM when the MAP signal is greater than 4.9 V for more than 0.4 second.
• DTC 121 can be set due to a signal circuit short to VREF or B+ or a failed MAP sensor.
• When DTC 121 is active the amber ENGINE lamp is illuminated.
DTC 122
Intake MAP signal out-of-range low
• DTC 122 is set by ECM when the MAP signal is less than 0.039 V for more than 0.4 second.
• DTC 122 can be set due to an open or short to ground on the signal circuit, a failed MAP sensor or an open V REF circuit or V REF short to ground.
• When DTC 122 is active the amber ENGINE lamp is illuminated.
DTC 123
Intake MAP signal in-range fault
• DTC 123 is set by ECM when the MAP signal is greater than 115 kPa (17 psi) absolute at low idle.
• DTC 123 can be set due to a restricted or plugged sensor inlet, open signal ground, VREF shorted to voltage source above 5.5 V, biased circuit, or a failed MAP sensor.
• When DTC 123 is active the amber ENGINE lamp is illuminated.
Tools
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
• Digital Multimeter (DMM)
• 3-Banana Plug Harness
• 500 Ohm Resistor Harness
• Breakout Box
• Breakout Harness
• Terminal Test Adapter Kit
