The powertrain control module (PCM) receives 2 ignition inputs from the ignition switch, IGN 0 and IGN 1. The PCM receives the crank request input with the ignition switch in the START position. The PCM uses a class 2 ignition mode message, and the voltage input from 2 separate systems to test the crank request circuit. If the PCM detects an improper input, DTC P0512 will set.
This diagnostic procedure supports the following DTC:
DTC P0512 Start Switch Circuit
No class 2 serial data circuit problem.
The PCM detects an improper crank request input.
• | The PCM will not illuminate the malfunction indicator lamp (MIL). |
• | The PCM will store conditions which were present when the DTC set as Failure Records information 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 |
---|---|---|---|
Schematic References: Starting and Charging Schematics Connector End View Reference: Engine Controls Connector End Views in Engine Controls - 4.6L or Power and Grounding Connector End Views in Wiring Systems | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Does the Crank Request parameter display No? | Go to Step 3 | Go to Step 4 |
3 |
Does the Crank Request parameter display Yes? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 5 |
4 |
Does the test lamp illuminate? | Go to Step 6 | Go to Step 9 |
5 |
Does the test lamp illuminate? | Go to Step 9 | Go to Step 7 |
6 | Test the crank voltage circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 8 |
7 | Test the crank voltage circuit for a high resistance or open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 8 |
8 | Inspect for poor connections at the ignition switch. 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 12 | Go to Step 10 |
9 | Inspect for poor connections at the PCM. 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 12 | Go to Step 11 |
10 | Replace the ignition switch. Refer to Ignition and Start Switch Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement? | Go to Step 12 | -- |
11 | Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 12 | -- |
12 |
Does the scan tool indicate that DTC P0512 passed? | System OK | Go to Step 2 |