Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Component Testing
2009 Chevrolet Tahoe Base, 4.8 CSECTION Component Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2010 GMC Yukon XL, 2010 GMC Yukon, 2010 Chevrolet Tahoe, 2010 Chevrolet Suburban, and 2010 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
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 Sensor 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.
- Using the J-23738-A or the J-35555 to apply 5 in Hg of vacuum to the MAP sensor, the parameter in the first column should decrease by 17 kPa. The acceptable range is indicated in the second column.
- Using the J-23738-A or the J-35555 to apply 10 in Hg of vacuum to the MAP sensor, the parameter in the first column should decrease by 34 kPa. 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 | 62-70 kPa |
| 95 kPa | 74-82 kPa | 57-65 kPa |
| 90 kPa | 69-77 kPa | 52-60 kPa |
| 80 kPa | 59-67 kPa | 42-50 kPa |
| 70 kPa | 49-57 kPa | 32-40 kPa |
| 60 kPa | 39-47 kPa | 22-30 kPa |
Erratic Signal Test
- Ignition OFF, remove the MAP sensor.
- Install a 3 A fused jumper wire between the 5 V reference circuit terminal C and the corresponding terminal 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 terminal B of the MAP sensor.
- Connect a DMM between the jumper wire from the terminal B of the MAP sensor and ground.
- Ignition ON, with the J-23738-A
or J-35555
, slowly apply vacuum to the sensor while observing the voltage on the DMM. The voltage should vary between 4.9-0.2 V without any spikes or dropouts.
- If the voltage is erratic, replace the MAP sensor.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.