Conditions For Setting DTC

If the PCM detects a fail-safe condition, it will attempt to illuminate the "N" range indicator light. The PCM sends a 12 volts pulse for 60-180 milliseconds. If it does not detect a voltage drop during the pulse, it waits about 60 seconds and pulses 12 volts again for 60-180 milliseconds. If the PCM does not detect the voltage drop before the ignition switch is turned off, the PCM will consider it as a short in the "N" range indicator light circuit and DTC 56 will be set.