Diagnostic guide for P1682

Diagnostic Guide for P1682 - Ignition 1 Switch Circuit 2

The P1682 code indicates a voltage discrepancy between two ignition 1 circuits supplied to the Engine Control Module (ECM). The goal of this diagnostic guide is to identify the root cause of the issue, which may involve inspecting the ignition switch, wiring, and the ECM itself.

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Difficulty

Intermediate

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Estimated Time

30-60 Minutes

Estimated Diagnostic Cost

$0-$100

Typical shop charge to perform this diagnostic process. Repair parts and labor are not included.

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Tools Needed

Multimeter, Wiring diagram, Basic hand tools, Cell phone camera

Safety Notes

Ensure the vehicle is in park or neutral with the parking brake engaged. Disconnect the battery before working on electrical components to avoid short circuits.

Step 1

Visual Inspection of Ignition Switch

Instruction Inspect the ignition switch for any visible damage or wear. Ensure that the switch is functioning properly when turned.

Expected result The ignition switch should appear intact and operate smoothly without any sticking or unusual resistance.

If Pass If the ignition switch appears functional, proceed to check the wiring harness connected to the switch.

If Fail If damage or wear is found, the ignition switch may need to be replaced.

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Step 2

Check Ignition Switch Harness

Instruction Using a multimeter, check the continuity of the ignition switch harness for any open or shorted circuits.

Expected result Continuity should be present between the ignition switch and the ECM without any shorts to ground.

If Pass If continuity is confirmed, proceed to check the voltage at the ECM.

If Fail If there is an open or short, inspect the wiring for damage or poor connections.

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Step 3

Measure Voltage at ECM

Instruction With the ignition in the 'run' position, measure the voltage at the ECM for both ignition 1 circuits.

Expected result Both circuits should show voltage readings within the manufacturer's specified range.

If Pass If both circuits are within range, the ECM may be faulty. Proceed to test the ECM.

If Fail If there is a significant voltage difference or no voltage, further investigate the power supply circuits.

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Step 4

Inspect Under Hood Fuse Block

Instruction Remove the under hood fuse block and inspect terminal #51 of the X3 connector for any signs of corrosion or arcing.

Expected result Terminal #51 should be clean and free of corrosion or damage.

If Pass If the terminal is in good condition, the issue may lie within the ECM itself.

If Fail If corrosion or arcing is found, replace the under hood fuse panel and terminal 51 in the harness.

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Step 5

Test Engine Control Module (ECM)

Instruction If all previous steps pass, test the ECM for proper operation using a compatible scan tool.

Expected result The ECM should communicate without issues and not show any additional fault codes.

If Pass If the ECM is functioning correctly, the problem may be intermittent or related to the ignition switch.

If Fail If the ECM fails to communicate or shows faults, it may need to be replaced.

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Coddy can help with this step only. Tell me what you tested or what result you got.