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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Camaro 🢒 Engine 🢒 Engine Controls - 5.7L 🢒 Powertrain Control Module Controlled Generator Diagnosis

Object Number: 585396 Size: SF
Engine Controls Component Views
Cruise Control Module, ECT Sensor, Engine Oil Level Switch and Generator
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The L-terminal circuit from the generator is a discrete circuit (a discrete circuit has no splices and only one source and one destination) into the PCM. The PCM applies ignition voltage to the generator L terminal circuit. A small amount of current flows from this circuit through the generator windings to create a magnetic field which starts the generator process. When the generator is at operating speed and producing voltage, a solid state switch for the L terminal circuit in the generator opens and the PCM detects that the initial startup current flow has stopped.

The PCM expects to detect low voltage on the L terminal circuit prior to the generator rotating at operating speed and conversely expects the circuit to be at ignition voltage potential when the generator is operational. When the PCM detects a fault (circuit shorted to ground, or circuit shorted to a voltage), the battery lamp will illuminate.

Diagnostic Aids

Important: 

   • Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
   • For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616 . Using this kit prevents any damage to the harness connector terminals. Refer to Using Connector Test Adapters in Wiring Systems.

A generator fault, such as a shorted output diode, malfunctioning regulator, an open or shorted rotor, or an open sense lead may cause a low battery charge condition. Refer to Diagnostic Starting Point - Engine Electrical in Engine Electrical.

Test Description

The numbers below refer to the step numbers on the Diagnostic Table.

  1. This step determines if a fault is present.

    2.

  2. A poor connection at the generator causes no output.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Install a scan tool.
  2. Start the engine.
  3. Monitor the Generator L terminal parameter using a scan tool.

Does the scan tool display the Generator L terminal as Inactive?

--

Go to DTC P1637 Generator L-Terminal Circuit

Go to Step 3

3

Measure the voltage at the battery using the DMM.

Is the battery voltage within the specified range?

13-15V

Go to Diagnostic Aids

Go to Step 4

4

Probe the Generator battery feed circuit using the J 35616-200 test lamp connected to ground. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 5

Go to Diagnostic Starting Point - Engine Electrical in Engine Electrical

5
  1. Disconnect the electrical connector from the generator.
  2. Start the engine.
  3. Measure the voltage to ground at the generator harness connector terminal B using the DMM. Refer to Measuring Voltage in Wiring Systems.

Is the voltage the same or more than the specified value ?

10V

Go to Step 10

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C2 located on the opposite side of the manufacturer's logo. Refer to Powertrain Control Module Replacement/Programming .
  3. Test the continuity from the generator circuit at the PCM harness connector to the B terminal of the generator harness connector using the DMM. Refer to Testing for Continuity in Wiring Systems.

Does the DMM indicate continuity?

--

Go to Step 8

Go to Step 7

7

Repair the open/high resistance in the generator circuit. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

System OK

--

8
  1. Inspect the terminal contact tension at the PCM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If you find a poor connection, repair the connection as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

Go to Step 9

9

Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Is the action complete?

--

System OK

--

10
  1. Inspect the terminal contact tension at the generator electrical connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If you find a poor connection, repair the connection as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

System OK

Go to Step 11

11

Replace the generator. Refer to Generator Replacement in Engine Electrical.

Is the action complete?

--

System OK

--