GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Vivant 🢒 Engine 🢒 Engine Controls - 2.0L (L34 GMDAT) 🢒 DTC 054

Circuit Description

The carbon monoxide (CO) adjuster is only used on vehicles that use leaded fuel. The CO adjuster is used in place of the oxygen sensor.

Conditions for Setting the DTC
    • The engine control system is in Open Loop.
    • The CO potentiometer is greater than 250 counts or the CO potentiometer is less than 5 counts.

Diagnostic Aids

Inspect the engine control module (ECM) wiring harness connectors for the following conditions:

    • Improper mating
    • Broken locks
    • Improperly formed or damaged terminals
    • A poor terminal-to-wire connection
    • A damaged harness

Step

Action

Value(s)

Yes

No

1

Determine whether the Diagnostic System Check - Engine Controls has been performed.

Was the Diagnostic System Check - Engine Controls performed?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Adjust the carbon monoxide (CO) adjuster.

Is the CO adjustable and in proper adjustment?

--

System OK

Go to Step 3

3
  1. To test the ability of the engine control module (ECM) to provide a 5-volt supply to the CO adjuster, begin by turning the ignition to LOCK.
  2. Disconnect the electrical connector at the CO adjuster.
  3. Turn ON the ignition.
  4. Measure the voltage between the CO adjuster terminal 3 and ground.

Does the voltage measure within the specified range?

4.5-5.5 V

Go to Step 5

Go to Step 4

4
  1. Turn the ignition to LOCK.
  2. Test for a short to battery voltage, a short to ground, or an open in the wire between the CO adjuster terminal 3 and the ECM connector terminal D8.

Is the condition found?

--

Go to Step 7

Go to Step 5

5

Test for a short to battery voltage, a short to ground, or an open in the wire between the CO adjuster terminal 1 and the ECM connector terminal B2.

Is the condition found?

--

Go to Step 7

Go to Step 6

6

Test for a short to battery voltage, a short to ground, or an open in the wire between the CO adjuster terminal 2 and the ECM connector terminal D2.

Is the condition found?

--

Go to Step 7

Go to Step 8

7
  1. Repair the wire or the connector terminal as needed.
  2. Clear any DTCs from the ECM.
  3. Perform the Diagnostic System Check - Engine Controls.

Is the repair complete?

--

System OK

--

8
  1. Disconnect the electrical connector at the CO adjuster.
  2. Measure the resistance between terminal 1 and terminal 2 of the CO adjuster.

Is the resistance equal to the specified value?

12 ohms

Go to Step 9

Go to Step 10

9

To test the ability of the CO adjuster to vary the resistance in the circuit, measure the resistance between terminal 1 and terminal 3 of the CO adjuster.

Does the resistance vary with the turn of the adjuster screw?

--

Go to Step 11

Go to Step 10

10
  1. Replace the CO adjuster.
  2. Clear any DTCs from the ECM.
  3. Perform the Diagnostic System Check - Engine Controls.

Is the repair complete?

--

System OK

--

11
  1. Replace the ECM.
  2. Perform the Diagnostic System Check - Engine Controls.

Is the replacement complete?

--

System OK

--