Component Testing

Skewed Sensor Test

1. Ignition OFF, remove the B74 Manifold Absolute Pressure Sensor from the engine. Connect the harness to the sensor, if disconnected.
2. Ignition ON, apply 17 kPa (5.0 in Hg) of vacuum to the B74 Manifold Absolute Pressure Sensor, with the GE-23738-A  . Verify the scan tool MAP pressure parameter decreases between 13 - 21 kPa (1.8 - 3.0 PSI).
   • If the parameter does not decrease between 13 - 21 kPa (1.8 - 3.0 PSI). 

     Replace the B74 Manifold Absolute Pressure Sensor.

   • If the parameter does decrease between 13 - 21 kPa (1.8 - 3.0 PSI). 
3. Apply 34 kPa (10.0 in Hg) of vacuum to the B74 Manifold Absolute Pressure Sensor, with the GE-23738-A  . Verify the scan tool MAP pressure parameter decreases between 30 - 38 kPa (4.4 - 5.5 PSI).
   • If the parameter does not decrease between 30 - 38 kPa (4.4 - 5.5 PSI). 

     Replace the B74 Manifold Absolute Pressure Sensor.

   • If the parameter does decrease between 30 - 38 kPa (4.4 - 5.5 PSI). 
4. All OK.

Erratic Signal Test

1. Ignition OFF, remove the B74 Manifold Absolute Pressure Sensor and disconnect the harness.
2. Install a 3 A fused jumper wire between the 5 V reference circuit terminal 1 of the sensor and the sensor harness.
3. Install a jumper wire between the low reference circuit terminal 2 of the sensor and ground.
4. Install a jumper wire to the signal circuit terminal 3 of the sensor.
5. Connect a DMM between the jumper wire and ground.
6. Ignition ON, observe the DC voltage on the DMM. Slowly apply between 0-15 kPa (0 - 4.4 in Hg) of vacuum to the sensor with the GE-23738-A  .
7. Verify the voltage changes, without any spikes or dropouts, between 0.2 - 4.9 V.
   • If not between 0.2 - 4.9 V or has spikes or dropouts 

     Replace the B74 Manifold Absolute Pressure Sensor.

   • If between 0.2 - 4.9 V and there are no spikes or dropouts 
8. All OK.