Diagnostic Instructions
DTC Descriptor
DTC P0381: Wait To Start Lamp Control Circuit
Diagnostic Fault Information
Perform the
Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit
| Short to Ground
| Open/High Resistance
| Short to Voltage
| Signal Performance
|
Wait To Start Signal
| P0381
| P0381
| P0381
| --
|
Circuit/System Description
Ignition voltage is supplied directly to the wait to start indicator. The engine control module (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 zero 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. If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the DTC to set.
Conditions for Running the DTC
| • | The ignition voltage is greater than 10 volts but less than 16 volts. |
Conditions for Setting the DTC
| • | The ECM 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. |
Action Taken When the DTC Sets
| • | The ECM stores the DTC information in memory. |
| • | The ECM records the operating conditions at the time the DTC sets. The ECM displays the failure information in the Failure Records on the scan tool. |
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. |
Diagnostic Aids
Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine
how many ignition cycles that the diagnostic test reported a pass and/or a fail.
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.
Reference Information
Schematic Reference
Connector End View Reference
Component Connector End Views
Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the driver information center (DIC).
- Connect a test lamp between the control circuit terminal B3 and the voltage supply circuit terminal A3.
- Ignition ON, command the wait to start indicator ON and OFF with the scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
| ⇒ | If the test lamp remains ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | If the test lamp remains OFF, test the control circuit for a short to voltage or an open/high
resistance. If the circuit tests normal, replace the ECM |
- If all circuits test normal, replace the DIC.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for the ECM or DIC replacement, setup, and programming.
