Component Testing
NOTE:
You must perform the Circuit/System Testing in order to verify the integrity of the MAP sensor circuits before proceeding with the Component Testing.
Skewed Signal Test
- Using the following steps and referencing the table below will determine if the MAP sensor is skewed.
- Ignition ON, engine OFF, observe the MAP Sensor scan tool parameter.
- Use the observed MAP Sensor scan tool parameter that is closest to a value that is indicated in the first column.
THEN
- Using the J 23738-A: Mityvac or the J 35555: Metal Mityvac to apply 5 in Hg of vacuum to the B74 MAP sensor, the parameter in the first column should decrease by 17 kPa (2.5 psi). The acceptable range is indicated in the second column.
- Using the J 23738-A: Mityvac or the J 35555: Metal Mityvac to apply 10 in Hg of vacuum to the B74 MAP sensor, the parameter in the first column should decrease by 34 kPa (4.7 psi). The acceptable range is indicated in the third column.
| Ignition ON, Engine OFF, MAP Sensor Parameter | MAP Sensor Parameter With 5 Inches of Vacuum Applied | MAP Sensor Parameter With 10 Inches of Vacuum Applied |
|---|---|---|
| 100 kPa | 79-87 kPa (11.5-12.6 psi) | 62-70 kPa (9-10.2 psi) |
| 95 kPa | 74-82 kPa (10.7-11.9 psi) | 57-65 kPa (8.3-9.4 psi) |
| 90 kPa | 69-77 kPa (10-11.2 psi) | 52-60 kPa (7.5-8.7 psi) |
| 80 kPa | 59-67 kPa (8.6-9.7 psi) | 42-50 kPa (6.1-7.3 psi) |
| 70 kPa | 49-57 kPa (7.1-8.3 psi) | 32-40 kPa (4.6-5.8 psi) |
| 60 kPa | 39-47 kPa (5.7-6.8 psi) | 22-30 kPa (3.2-4.4 psi) |
Erratic Signal Test
- Ignition OFF, remove the B74 MAP sensor.
- Install a 3 A fused jumper wire between the 5 V reference circuit terminal 1 and the corresponding terminal of the B74 MAP sensor.
- Install a jumper wire between the low reference circuit terminal 2 of the B74 MAP sensor and ground.
- Install a jumper wire at terminal 3 of the B74 MAP sensor.
- Connect a DMM between the jumper wire from terminal 3 of the B74 MAP sensor and ground.
- Ignition ON, with the J 23738-A:
Mityvac or J 35555:
Metal Mityvac, slowly apply vacuum to the sensor while observing the voltage on the DMM. The voltage should vary between 0-5.2 V, without any spikes or dropouts.
- If the voltage reading is erratic, replace the B74 MAP sensor.