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? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
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. Did the throttle blade angle follow the commanded angle? | -- | Go to Step 3 | Go to Step 4 |
3 |
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) 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/ETC ignition 1 voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 7 |
7 |
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 10 |
8 | Test the ECM ignition 1 voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 9 |
9 |
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 10 |
10 |
Does the voltage measure near the specified value? | 12 V | Go to Step 11 | Go to Step 12 |
11 |
Does the voltage measure near the specified value? | 12 V | Go to Step 14 | Go to Step 13 |
12 | Test the ECM/ETC ignition 1 voltage circuit for an open or 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 |
13 | Test the ECM ignition 1 voltage circuit for an open or 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 14 |
14 | Test for poor connections at the ECM connectors. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 15 |
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 |
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 in Vehicle DTC Information | System OK |
