GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Epica 🢒 Engine 🢒 Engine Controls - 2.0L (L34 GMDAT) 🢒 DTC 029

Circuit Description

When the ignition is turned ON, the electronic control module (ECM) applies ground to the fuel pump relay coil side. The ECM will apply this ground for 2 seconds or until reference pulses are received by the ECM from the crankshaft position (CKP) sensor. This activates the fuel pump relay, applying battery voltage to the fuel pump.

Conditions for Setting the DTC

The fuel pump relay circuit is shorted to ground for at least 1.6 seconds.

Diagnostic Aids
    • Inspect the ECM wiring harness connectors for improper mating, broken locks, improperly formed or damaged terminals, a poor terminal-to-wire connection, and a damaged harness.
    • If the connections and the wiring harness are in good condition, connect a test light between the fuel pump relay connector terminal 85 and battery positive while moving related connectors. If the fault is induced, the test light will turn ON. This may help to isolate the location of an intermittent problem.

Step

Action

Yes

No

1

Perform the Diagnostic System Check.

Is the Diagnostic System Check complete?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2
  1. Disconnect the fuel pump relay.
  2. Connect a test light between the fuel pump relay connector terminal 85 and battery positive.

Is the test light ON?

Go to Step 3

Go to Diagnostic Aids

3

Disconnect the engine control module (ECM) connector.

Is the test light ON?

Go to Step 4

Go to Step 5

4
  1. Repair the short to ground in the wire between the fuel pump relay connector terminal 85 and the ECM connector terminal A12.
  2. Clear any DTCs from the ECM.
  3. Perform the Diagnostic System Check.

Is the repair complete?

System OK

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5
  1. Replace the ECM. Refer to Engine Control Module Replacement .
  2. Perform the Diagnostic System Check.

Is the repair complete?

System OK

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