The DTC P1500 Start Switch Circuit diagnostic monitors the voltage signal that is sent from the ignition switch when starting the engine. When the engine is being cranked, battery voltage is applied to the powertrain control module (PCM). The starter signal is mainly used to increase the fuel injection volume for the starting injection control. This signal passes through the transmission range (TR) switch or the clutch pedal position (CPP) switch. If this signal is not detected during engine cranking, the PCM will still allow the engine to start.

The engine was started and is running.

The engine is running but no starter signal was detected when the engine was cranking.

OR

A high voltage is present at the PCM for at least 3 minutes after starting the engine.

If the DTC P1500 is intermittent, driving the vehicle under the following conditions can verify whether the fault is present. Perform the scan tool Clear DTC Information function. Road test the vehicle while monitoring the DTC P1500 diagnostic on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If DTC P1500 appears in the Not Ran Since Code Cleared list, the P1500 diagnostic has not yet run. When DTC P1500 does not appear in the Not Ran Since Code Cleared list, the P1500 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the P1500 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.

An intermittent malfunction may be caused by a fault in the starter signal sensor circuit. Inspect the wiring harness and the components for an intermittent condition. Refer to Intermittent Conditions .

If DTC P1500 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was first set.

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

1. The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. This step determines if a fault is present.

3. This step checks for the correct voltage on the crank signal circuit. While the engine is cranking, the PCM crank signal terminal should have a voltage reading of 6 to 12 volts and after the engine is started, the PCM crank signal terminal should have a voltage reading of 0 volts.

7. Clearing the DTCs by removing the DOME fuse also clears the PCM long term memory. Using the scan tool to clear DTCs leaves the long term memory active. DTC emitting diagnostics may not run to completion as expected unless the long term memory is cleared. Removal of the DOME fuse also clears the time display of the radio. The DTC P01500 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P01500 appears in the Not Ran Since Code Cleared list, the DTC P01500 diagnostic has not yet run. When the DTC P01500 does not appear in the Not Ran Since Code Cleared list, the DTC P01500 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC P01500 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.