The engine control module (ECM) / powertrain control module (PCM) receives 2 ignition inputs from the ignition switch, ignition 1 signal, and ignition accessory signal. The ECM/PCM receives the crank input from a serial data message from the body control module (BCM). The ECM/PCM determines the state of the ignition switch based on these 3 inputs. If the ECM/PCM detects an improper ignition accessory signal, DTC P1633 will set.
This diagnostic procedure supports the following DTC:
DTC P1633 Ignition 0 Switch Circuit
No class 2 serial data circuit problem.
The ECM/PCM detects an improper ignition accessory input voltage.
• | The ECM/PCM will not illuminate the malfunction indicator lamp (MIL). |
• | The ECM/PCM will store conditions which were present when the DTC set as Failure Records only. |
• | 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 |
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Schematic Reference: Engine Controls Schematics for the 2.0L engine, Engine Controls Schematics for the 2.2L (L61) engine or Engine Controls Schematics for the 2.4L engine Connector End View Reference: Powertrain Control Module Connector End Views for the 2.0L engine, Engine Control Module Connector End Views for the 2.2L (L61) engine or Engine Control Module Connector End Views for the 2.4L engine | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Does the scan tool display ON? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 |
3 |
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 ECM/PCM for an open or for a high resistance. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 7 | -- |
5 | Inspect for poor connections at the harness connector of the ECM/PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 7 | Go to Step 6 |
6 | Replace the ECM/PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 7 | -- |
7 |
Does the DTC fail this ignition? | Go to Step 3 | System OK |