GM Service Manual Online
For 1990-2009 cars only

Refer to

Cell 20: Powertrain Control Module, IP Fuse Block, Fuel injectors and Fuel Pump Control


Object Number: 330334  Size: FS
Engine Controls Components
Cell 20: Cruise Control Circuits, Electronic Throttle Actuator ContRol Module
Cell 20: Crankshaft Position Sensor, Camshaft Position Sensor, Fuse/Relay Center, Powertrain Control Module
Handling ESD Sensitive Parts Notice
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Diagnostic Aids

    • The PCM has integrated circuits that are fault protected. Therefore, if a circuit has failed, the integrated circuits may not be damaged. If this is the case, the IC will keep the circuit open until you have corrected the fault in the circuit.
    •  When you have corrected the fault, reinstall the PCM.
    • Inspect the circuit.
    • Replace the PCM only if the circuit is still inoperative.

Test Description

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

  1. This step determines if the ignition feed circuit to the injectors are OK.

  2. This step determines if the injector control circuits are OK.

  3. This step determines if there is an internal PCM short to ground for an injector control circuit.

Injector Circuit Diagnosis

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Disconnect the injector harness at the rear of the intake manifold.
  2. Connect a test lamp to a ground.
  3. Turn ON the ignition leaving the engine OFF.
  4. Using the test lamp, probe the injector ignition feed circuits.

Is the test lamp on for both of the injector feed circuits?

--

Go to Step 6

Go to Step 3

3

Is the test lamp ON for only one of the injector feed circuit?

--

Go to Step 5

Go to Step 4

4

Check the injector fuse.

Is the fuse open?

--

Go to Step 10

Go to Step 11

5

Check for an open on the affected injector feed circuits.

Was a problem found?

--

Go to Step 12

--

6

  1. Install the injector test lamp J 34730-380 on the injector harness connector (PCM side).
  2. Crank the engine.

Does the injector test lamp flash for each injector?

--

Go to Fuel Injector Solenoid Coil Test

Go to Step 7

7

Is the injector test lamp on steady for any injector circuit?

--

Go to Step 8

Go to Step 9

8

  1. Install the injector test lamp.
  2. Turn OFF the ignition.
  3. Disconnect the PCM connectors.
  4. Turn ON the ignition leaving the engine OFF.

Is the injector test lamp OFF?

--

Go to Step 16

Go to Step 13

9

Check for an open injector control circuit.

Was a problem found?

--

Go to Step 12

Go to Step 14

10

Repair the short to ground on the injector feed circuit, that did not illuminate the test lamp.

Is the action complete?

--

Go to Step 12

--

11

Repair the open on both of the injector feed circuits.

Is the action complete?

--

Go to Step 17

--

12

Repair circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 17

--

13

Repair short to ground in the injector control circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 17

--

14

Check the terminal contact at the PCM.

Was a problem found?

--

Go to Step 15

Go to Step 16

15

Repair terminal contact as necessary.

Is action complete?

--

Go to Step 17

--

16

  1. Replace the PCM.
  2. Refer to Powertrain Control Module Replacement .

Is the action complete?

--

Go to Step 17

--

17

  1. Using the scan tool, select the DTC and the Clear Info.
  2. Attempt to start the engine.

Does the engine start and continue to run?

--

Go to Step 18

Go to Step 2

18

  1. Allow the engine to idle until normal operating temperature is reached.
  2. Select the DTC and the Failed This Ign.

Are any DTCs displayed that have not been diagnosed?

--

Go to the applicable DTC table

Go to Step 19

19

Use the scan tool in order to display the Capture Info and the Review Capture Info function.

Are there any DTCs displayed that have not been diagnosed?

--

Go to the applicable DTC table

System OK