Component Testing
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
You must perform the Circuit/System Testing in order to verify the integrity of the MAP sensor circuits before proceeding with the Component Testing.
Erratic Signal Test
- Ignition OFF, disconnect and remove the MAP sensor.
- Install a 3A fused jumper wire between the 5-volt reference circuit terminal C and the corresponding terminal C of the MAP sensor.
- Install a jumper wire between the low reference terminal A of the MAP sensor and ground.
- Install a jumper wire at the signal terminal B of the MAP sensor.
- Connect a DMM between the jumper wire from terminal B of the MAP sensor and ground.
- Ignition ON, install the J 35555
or J 23738-A
to the MAP sensor port. Slowly apply vacuum to the sensor while monitoring the voltage on the DMM. The voltage should vary between 4.9-0.04 volts, without any spikes or dropouts.
- If the voltage is erratic, replace the MAP sensor.