GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Epica 🢒 Engine 🢒 Engine Controls - 2.5L (LBK) 🢒 DTC P1611

Circuit Description

The engine controls ignition relay or ENG MAIN relay is controlled by the engine control module (ECM) depending upon input from the ignition switch. Battery positive voltage is supplied to the relay coil and switch. When the ignition switch is turned to the ON or Accessory position, the ECM will provide ground on the control circuit of the relay using a low side driver. This will allow voltage through the relay switch contacts to the components. The ECM monitors the voltage level on the control circuit of the relay. If the ECM detects an open or short to ground on the control circuit of the relay, DTC P1611 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1611 Engine Controls Ignition Relay Control Circuit Low Voltage

Conditions for Running the DTC
    • The ignition is ON or the engine is operating.
    • DTC P1611 runs continuously once the above condition is met.

Conditions for Setting the DTC

The ECM detects an open or short to ground on the control circuit of the relay for 2.4 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.

Diagnostic Aids
    • For an intermittent condition, refer to Intermittent Conditions .
    • The following table illustrates the ENG Main relay terminal location in the underhood fuse block:

ENG Main Relay Terminal Identification

Feeback

Control

B+ - Coil

B+ - Switch

Front of Vehicle

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests the control circuit for a shorted to voltage.

    2.

  2. This step tests the control circuit for an open.

    3.

  3. This step tests the control circuit for high resistance.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

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

1

Did you perform the Diagnostic System Check - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the Ignition 1 Signal parameter with a scan tool.

Is the voltage less than the specified value?

2 Volts

Go to Step 4

Go to Step 3

3

  1. Observe the Freeze Frame/Failure Records data for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. 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 4

Go to Intermittent Conditions

4
  1. Turn OFF the ignition.
  2. Disconnect the ENG MAIN relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive voltage circuit of the ENG MAIN relay coil with a test lamp connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 12

5
  1. Turn OFF the ignition.
  2. Probe the control circuit of the ENG MAIN relay with a test lamp connected to battery positive voltage.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 6

6
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the control circuit of the ENG MAIN relay with a test lamp connected to battery positive voltage.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 9

7
  1. Turn OFF the ignition.
  2. Disconnect the ECM 1 fuse in the underhood fuse block.
  3. Measure the resistance of the battery positive circuit of the ENG MAIN relay coil from the ECM 1 fuse terminal to the relay terminal.

Is the resistance less than the specified value?

3 ohms

Go to Step 8

Go to Step 12

8
  1. Turn ON the ignition, with the engine OFF.

    2. Important: Use the J 35616-200 Test Lamp Kit for this test. If the J 35616-200 is not available, use a test lamp that measures between 25-30 ohms.

  2. Probe the control circuit of the ENG MAIN relay with a test lamp connected to battery positive voltage.
  3. Measure the voltage from the probe of the test lamp to a good ground with a DMM.

Is the voltage less than the specified value?

2.5 V

Go to Step 10

Go to Step 9

9

Test the control circuit of the ENG MAIN relay for one of the following conditions:

    • A short to ground
    • An open
    • High resistance

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 11

10

Test for shorted terminals and poor connections at the ENG MAIN relay. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

11

Test for shorted terminals and poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

12

Repair an open or high resistance in the battery positive voltage circuit of the ENG MAIN relay coil. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 15

--

13

Replace the ENG MAIN relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15
  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 16

16

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK