GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2004 🢒 ION 🢒 Engine 🢒 Engine Electrical 🢒 DTC P1633

Circuit Description

The powertrain control module (PCM) receives 2 ignition inputs from the ignition switch, ignition 1 signal and ignition accessory signal. The PCM receives the crank input from a serial data message from the BCM. The PCM determines the state of the ignition switch based on these 3 inputs. If the PCM detects an improper ignition accessory signal, DTC P1633 will set.

Conditions for Running the DTC

No Class 2 serial data circuit problem.

Conditions for Setting the DTC

The PCM detects an improper ignition accessory input voltage.

Action Taken When the DTC Sets
    • The PCM will not illuminate the malfunction indicator lamp (MIL).
    • The PCM will store conditions which were present when the DTC set as Fail Records only.

Conditions for Clearing the DTC
    • The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using the scan tool Clear DTC Information function.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics in Engine Controls 2.0L (LSJ)

Connector End View Reference: Powertrain Control Module Connector End Views in Engine Controls 2.0L (LSJ)

1

Did you perform the Diagnostic System Check - Engine Electrical?

Go to Step 2

Go to Diagnostic System Check - Engine Electrical

2
  1. Turn ON the ignition with the engine OFF.
  2. With a scan tool observe the Ignition Accessory Signal parameter in the Engine Data list.

Does the scan tool display ON?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3
  1. Turn OFF the ignition
  2. Disconnect the PCM.
  3. Connect a test lamp between the accessory voltage circuit of the powertrain control module (PCM) and a good ground.
  4. Turn the ignition switch to the accessory and ON positions.

Does the test lamp illuminate with the ignition switch in both the accessory and ON positions?

Go to Step 5

Go to Step 4

4

Repair the accessory voltage circuit of the PCM for an open or for a high resistance. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 7

--

5

Inspect for poor connections at the harness connector of the powertrain control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

Go to Step 6

6

Important: Program the PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 7

--

7
  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.

Does the DTC fail this ignition?

Go to Step 3

System OK