GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Cobalt 🢒 DTC 🢒 DTC P1682

Circuit Description

The throttle actuator control (TAC) system uses an ignition voltage supply separate from the engine control module (ECM) supply. If the ECM detects a voltage difference between the two circuits, this DTC will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1682 Ignition 1 Switch Circuit 2

Conditions for Running the DTC
    • The ignition is ON.
    • DTC P1682 runs continuously when the above condition is met.

Conditions for Setting the DTC
    • The ignition 1 voltage is less than 10 volts.
    • The above condition is present for more than 1.6 seconds.

Action Taken When the DTC Sets
    • The control module stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
    • The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC
    • A current DTC Last Test Failed clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • Clear the DTC with a scan tool.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Turn ON the ignition, with the engine OFF.

    2. Important: Operating the throttle blade with the Throttle Blade Control function of the scan tool may cause additional DTCs to set. Do not attempt to diagnose DTCs set during this function.

  2. Command the throttle blade to 100 percent and back to 0 percent with a scan tool. Exit the throttle blade control function.

Did the throttle blade angle follow the commanded angle?

--

Go to Step 3

Go to Step 4

3

  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4

Probe both sides of the electronic temperature control ECM/ETC fuse with a test lamp connected to ground.

Does the test lamp illuminate on both sides of the fuse?

--

Go to Step 5

Go to Step 6

5

Probe both sides of the engine control module (ECM)/PCM fuse with a test lamp connected to ground.

Does the test lamp illuminate on both sides of the fuse?

--

Go to Step 10

Go to Step 8

6

Test the ECM/PCM ignition 1 voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 16

Go to Step 7

7
  1. Test the supply voltage to the ECM/PCM fuse for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .
  2. If a short to ground is found, replace the affected fuse.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 10

8

Test the ECM/PCM ignition 1 voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 16

Go to Step 9

9
  1. Test the supply voltage to the ECM/PCM fuse for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .
  2. If a short to ground is found, replace the affected fuse.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 10

10
  1. Disconnect the ECM connector containing the ECM/PCM ignition 1 voltage.
  2. Measure the voltage on the ECM/PCM ignition 1 voltage circuit with a DMM connected to ground.

Does the voltage measure near the specified value?

12 V

Go to Step 11

Go to Step 12

11
  1. Disconnect the ECM connector containing the ECM/PCM ignition 1 voltage.
  2. Measure the voltage on the ECM ignition 1 voltage circuit with a DMM connected to ground.

Does the voltage measure near the specified value?

12 V

Go to Step 14

Go to Step 13

12

Test the ECM/PCM ignition 1 voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

13

Test the ECM/PCM ignition 1 voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 16

Go to Step 14

14

Test for poor connections at the ECM connectors. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 16

Go to Step 15

15

Replace the ECM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 16

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16
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 17

17

Observe the Capture Info with a scan tool.

Are there any DTCs that have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK