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Discussion Starter #1
I've seen and searched posts about it, but never really found an answer. Not the same as P0380. But if anyone has had this, what did you replace?
When it first occurred, I had re-installed the DSP2 pin, is there a pin that is dedicated to the glow plug system that may not be making contact?

Everything was fine before and immediately after the code set and won't leave.
I haven't checked the pins, too busy, or em lazy. Trucks seems o start fine just turns over a lil longer.
 

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It's related to the wait to start indicator. Is it working properly? It says the code will go away after 40 warm up cycles if the condition that set it no longer exists.
It can be cleared with a scan tool.
The ECM sensed voltage being sent to the light was out of spec.
Check the connectors.
 

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Discussion Starter #3
I haven't seen the WTS lamp since it stored, I can keep the MIL from showing, but I'm tryin to figure out why it is actually setting.
I broke the lil clip inside the ECM connector, is why I'm dreading pulling it back off, it was a pain to keep all those lil pins down and in correctly.
I guess a defaulty glow plug or module wouldn't set this, huh? Probably a different code?
 

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DTC P0381

<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1457323&psdid=1058&evc=sm#ss1-1457323">Circuit Description

Ignition voltage is supplied directly to the wait to start indicator. The powertrain control module (PCM) 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 PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be low, near 0 volts. When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the DTC to set.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1457323&psdid=1058&evc=sm#ss2-1457323">DTC Descriptor

This diagnostic procedure supports the following DTC:
DTC P0381 Wait To Start Lamp Control Circuit
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1457323&psdid=1058&evc=sm#ss3-1457323">Conditions for Running the DTC

The ignition voltage is greater than 6 volts but less than 18 volts.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1457323&psdid=1058&evc=sm#ss4-1457323">Conditions for Setting the DTC

The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match.
The condition must be present for a minimum of 5 seconds.​
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1457323&psdid=1058&evc=sm#ss5-1457323">Action Taken When the DTC Sets

The PCM stores the DTC information in memory.
The PCM records the operating conditions at the time the DTC sets. The PCM displays the failure information in the Failure Records on the scan tool.​
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1457323&psdid=1058&evc=sm#ss6-1457323">Conditions for Clearing the DTC

The history DTC clears after 40 malfunction free warm-up cycles.
The DTC becomes history when the conditions for setting the DTC are no longer present.
The PCM receives the clear code command from the scan tool.​
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1457323&psdid=1058&evc=sm#ss7-1457323">Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.
The wait to start indicator illuminates only with the ignition ON and the engine OFF. The wait to start indicator will not illuminate during post-start glow plug operation.
The wait to start indicator will not stay ON for long at higher engine temperatures.
 
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