Circuit/System Testing
WARNING: This page is about a different variant/trim than selected.
Perform the Diagnostic System Check - Vehicle .
- Start the engine.
- Monitor the diagnostic trouble code (DTC) information with the scan tool.
- If DTC P0641 or P0651 is also set, then correct DTC P0641 or P0651 first.
- Inspect for the following conditions:
- Disconnected, damaged, or incorrectly routed vacuum hoses
- MAP sensor disconnected from vacuum source
- Restrictions in the MAP sensor vacuum source
- Intake manifold vacuum leaks
- For properly functioning oxygen sensor, refer to Scan Tool Data List .
- With the ignition ON, and the engine OFF
- Disconnect the MAP sensor.
- Measure for 4.8-5.2 volts from the 5-volt reference circuit of the MAP sensor to a good ground, with a DMM.
- If more than 5.2 volts, then test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the control module.
- If less than 4.8 volts, then test the 5-volt reference circuit for high resistance, an open, or an intermittent and poor connection or at the control module. If the circuit tests normal, replace the control module.
- Use a scan tool and observe the MAP sensor for less than 12 kPa.
- If the MAP sensor is more than 12 kPa, then test the MAP sensor signal circuit for a short to voltage. If the circuit tests normal, replace the control module.
- Use a 3-amp fused jumper wire and connect it between the MAP sensor 5-volt reference circuit and the MAP sensor signal circuit.
- Use a scan tool and observe the MAP sensor for more than 103 kPa.
- If the MAP sensor is less than 103 kPa, then test the MAP sensor signal circuit for a short to ground, an open or high resistance. If the circuit tests normal, replace the control module.
- Turn OFF the ignition and allow the control module to power down.
- With a DMM, measure for less than 5 ohms of resistance between the low reference circuit of the MAP sensor and a good ground.
- If the resistance is more than 5 ohms, then test the circuit for an open or high resistance. If the circuit tests normal, replace the control module.
- Turn OFF the ignition.
- Remove the MAP sensor from the engine vacuum source. Leave the MAP sensor connected to the engine harness.
- Connect the J 23738-A to the MAP sensor. See Special Tools .
- Turn ON the ignition, with the engine OFF.
- Observe the MAP sensor pressure with a scan tool.
- Apply vacuum with the J 23738-A
to the MAP sensor in 1 inch Hg increments until 15 inch Hg is reached. See Special Tools
. Each 1 inch Hg should decrease MAP sensor pressure by 3-4 kPa. Monitor the MAP sensor pressure to see if the decrease in pressure is consistent.
- If decrease in pressure is not consistent then, test for intermittent and poor connection at the MAP sensor. If connections test OK, replace the MAP sensor.
- Apply vacuum with J 23738-A
until 20 inch Hg is reached. See Special Tools
. Observe the MAP sensor pressure for less then 34 kPa.
- If more than 34 kPa, test for an intermittent and for a poor connection at the MAP sensor. If connections test OK, replace the MAP sensor.