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map sensor pin swap

stock top locking tab up, wires facing you

pin 1 - 5v ref - grey

pin 2 - signal - green

pin 3 - Ground - orange

duramax sensor wiring

Pin 1 - 5 volts - gray

Pin 2 - Ground (low reference) - orange/black

Pin 3 - Signal to PCM - light green


GM 1 bar map sensor Linear and offsets for HPtuners software

MAP Sensor Linear: 94.43

MAP Sensor Offset: 10.34

GM 2 bar map sensor Linear and offsets for HPtuners software

MAP Sensor Linear: 207.66

MAP Sensor Offset: 9

GM 2.5 bar map sensor Linear and offsets for HPtuners software

MAP Sensor Linear: 244.68 kPa

MAP Sensor Offset: 10.21 kPa

GM 3 bar map sensor Linear and offsets for HPtuners software

MAP Sensor Linear: 329.41

MAP Sensor Offset: -6.35

GM 3.3 bar map sensor Linear and offsets for HPtuners software

MAP Sensor Linear: 333.33

MAP Sensor Offset: 33.33

Linked information from a website showing some map info

3 digit numbers for identification:

1 Bar: 039, 460, 883, 876, 153

2 Bar: 886, 012, 539, 609, 701

3 Bar: 749, 861

The logic module uses the manifold absolute pressure (MAP) sensor to determine the absolute pressure (not the relative to atmospheric pressure) of the air inside the intake manifold and the atmosphere (barometric pressure).

This information is used to determine the density of the air entering the combustion chamber (in conjunction with the IAT(Intake Air temperature) sensor), which is used when calculating the proper air/fuel mixture for the engine, especially at WOT since the system is not in closed-loop at this time.

It is also used to help adjust the IAC(Idle Air Control) motor during idle.

It uses a silicon wafer that is thinner in the center (0.001") than around the edges (0.045"), which causes it to act as a diaphram.

It is mounted with a perfect vacuum beneath the chip so that the air pressure from the other side flexes the chip.

This flexing causes a change in resistance and the circuitry inside the sensor converts this to a voltage ranging from 0.02V to 4.94V when the output is pulled up towards 5V by the ECM(Electronic control module).

1 Bar MAP sensors are used on NA(naturally asperated) vehicles.

2 Bar MAP Sensors are used on forced induction vehicles(Turbo & Supercharged). They can measure up to 2x the apmospheric pressure(29.4psi), so that means it can measure up to 14.7psi boost(the atmosphere is 14.7psi + 14.7psi from the turbo/supercharger).

3 Bar MAP sensors can measure up to 44.1psi, which translates to 29.7psi boost from a Turbo/supercharger.

They all share a common pinout, although the connector keying may be different:

Pin A -- Ground

Pin B -- Sensor output

Pin C -- +5 volts

Places to order MAP Sensors

You can order them direct from:

PN# MSD-2313 3bar MAP

PN# MSD-2312 2bar MAP

PN# MSD-2311 1bar MAP


PN# 12223861 3bar MAP

PN# 16040609 2bar MAP

PN# 16137039 1bar MAP

The chart below describes the pressure-to-voltage relationship of the stock GM Turbo MAP sensor (2 bar):

Manifold Pressure
(relative sea level / absolute)
2 Bar
MAP Output
14.31psi / 29.01psi
14.00psi / 28.70psi
13.00psi / 27.70psi
12.00psi / 26.70psi
11.00psi / 25.70psi
10.00psi / 24.70psi
9.00psi / 23.70psi
8.00psi / 22.70psi
6.00psi / 20.70psi
4.00psi / 18.70psi
2.00psi / 16.70psi
0.00psi / 14.70psi
5.00inHg / 12.24psi
10.00inHg / 9.78psi
15.00inHg / 7.33psi
20.00inHg / 4.87psi
25.00inHg / 2.41psi
29.10inHg / 0.40psi

MAP sensor output based on altitude (Ignition "ON" and engine stopped)

GM 1bar, 2bar, 3bar

1 PSI = 2.036" of Mercury (HG)

1" mercury = 0.4911541 PSI

Formula for the GM 3 Bar MAP sensor is (V*8.94)-14.53

I have no idea why it's 14.53 and not 14.696, [rounds up to 14.7] but it works out on GM's chart every time. It is possible that Detroit is slightly above sea level, and you can use 12.11 in the formula for 1 mile above sea level.

Altitude Voltage Range
Meters Feet --------------
Below 305 Below 1000 3.8--5.5V
305--610 1000--2000 3.6--5.3V
610--914 2000-3000 3.5--5.1V
914--1219 3000--4000 3.3--5.0V
1219--1524 4000--5000 3.2--4.8V
1524--1829 5000--6000 3.0--4.6V
1829--2133 6000--7000 2.9--4.5V
2133--2438 7000--8000 2.8--4.3V
2438--2743 8000--9000 2.6--4.2V
2743--3048 9000-10000 2.5--4.0V
Low altitude = High Pressure = High Voltage

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