Powertrain Controls - ECM/PCM

Trouble Code 16 Chart:

PCM Voltage Circuit:

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) will perform a test of the ignition voltage applied to pin "C3" and "C4" of the PCM. A comparison is done between the voltage applied to the input and a calibrated voltage value. During the time a low voltage failure is present, all PCM outputs will become disabled. This may result in the additional setting of other seemingly unrelated Diagnostic Trouble Codes (DTC).

DTC 16 WILL SET WHEN
The PCM detects 8 volts or less on the ignition feed circuit 239 and 639, engine speed is greater than 1000 RPM with both conditions met for 5 seconds.

ACTION TAKEN (PCM) WILL DEFAULT TO
The Malfunction Indicator Lamp (MIL) will become illuminated.

DTC 16 WILL CLEAR WHEN
A current DTC 16 will clear when ignition feed voltage is detected above 8 volts. A History DTC 16 will clear after 50 consecutive ignition key cycles without a current DTC 16 being stored.

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

1. Test generator output to determine proper operation of the voltage regulator. Run engine at moderate speed and measure voltage across the battery. If less than 8 volts, repair generator.

DIAGNOSTIC AIDS
An intermittent may be caused by poor connections, chaffed insulation, a wire broken inside the insulation or poor PCM grounds.
^ Intermittent Test - Monitor "System Volts" display with a Tech 1 scan tool while moving related connectors. If the failure is induced, the display will abruptly change. This may help to isolate the location of the malfunction.