2004 Duramax - P0381 Wait To Start Lamp Circuit

[C172]

2004 GMC Duramax with code p0381, wait to start lamp control circuit, ignition voltage to indicator, ecm controls lamp by grounding the circuit via an internal switch called a driver. the rundown says to disconnect c2 connector at ecm and chech for voltage the pin is dk blue #36, going by the cluster schematic. think the ecm is on the left of fan shroud with a cover aroud it but checking both plug connectors dont see dark blue #36. can't find any pin diagram in shopkey, I'm confused.

Thanks jack

[Pauls Automotive]

I've been trying to look into this but haven't had much luck. Any chance you can give vehicle specific details, YMM and VIN?

[brianp87]

That code means either Wait to start circuit is shorted to ground, Wait to start circuit is shorted to voltage, ECM connector is damaged or ECM is bad.
With the key on the system voltage from 6-18v, and the ECM detected detects that the commanded state of the driver and the actual state of the control circuit do not match for 5 seconds. Ignition voltage is supplied directly to the Wait To Start indicator. The ECM controls the lamp by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the ECM. When the ECM is commanding a component 'on", the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding the control circuit to a component "off", the voltage potential of the circuit should be high, near battery voltage.

[C172]

found the connector diagram i will check it tomorrow when it comes in. jack

[brianp87]

Any luck?