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.
Test Description
The number below refers to the step number on the diagnostic table.
- 7: This step tests for the proper operation of the circuit in the low voltage range.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Engine Control Module (ECM) Connector End Views |
||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | - | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Are DTCs P0641 or P0651 set? | - | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | Go to Step 3 |
| 3 |
IMPORTANT:
The cooling fans are commanded ON when certain DTCs are set.
|
-39°C (-38°F) | Go to Step 5 | Go to Step 4 |
| 4 |
|
- | Go to Step 5 | Go to Inducing Intermittent Fault Conditions in Wiring Systems and Intermittent Conditions |
| 5 |
|
5.2 V | Go to Step 6 | Go to Step 7 |
| 6 |
IMPORTANT:
If a short to voltage occurs the sensor may be damaged.
|
- | Go to Step 16 | Go to Step 13 |
| 7 | Connect a 3-amp fused jumper wire between the signal circuit of the IAT sensor and the low reference circuit of the IAT sensor. Refer to Using Fused Jumper Wires
in Wiring Systems. Is the IAT Sensor parameter more than the specified value? |
128°C (262°F) | Go to Step 11 | Go to Step 8 |
| 8 | Connect a 3-amp fused jumper wire between the signal circuit of the IAT sensor and a good ground. Is the IAT Sensor parameter more than the specified value? |
128°C (262°F) | Go to Step 10 | Go to Step 9 |
| 9 | Test the IAT signal circuit for an open circuit or for high resistance. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 16 | Go to Step 13 |
| 10 | Test the IAT low reference circuit for an open circuit or for high resistance. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 16 | Go to Step 13 |
| 11 | Test the IAT signal circuit for a short to any 5-volt reference circuit. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 16 | Go to Step 12 |
| 12 | Test for an intermittent and for a poor connection at the MAF/IAT sensor. Refer to Testing for Intermittent Conditions and Poor Connections
, Repairing Connector Terminals
, and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 16 | Go to Step 14 |
| 13 | Test for an intermittent and for a poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections
, Repairing Connector Terminals
, and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 16 | Go to Step 15 |
| 14 | Replace the MAF/IAT sensor. Refer to Mass Air Flow (MAF) Sensor Replacement
. Did you complete the replacement? |
- | Go to Step 16 | - |
| 15 | Replace the ECM. Refer to Control Module References
in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? |
- | Go to Step 16 | - |
| 16 |
|
- | Go to Step 2 | Go to Step 17 |
| 17 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? |
- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.
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