GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The diagnostic test checks for an engine stall or near stall and sets DTC P1599 if a stall condition is detected. A partial start where engine RPM exceeds 400 RPM and the engine does not start, will also cause DTC P1599 to set. This DTC is designed to capture snapshot data of the stall condition.

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

    •  Engine speed drops below 152 RPM after exceeding 400 RPM this ignition cycle.
    •  No references pulses have been received for 0.75 second.

Action Taken When the DTC Sets

    •  The Malfunction Indicator Lamp (MIL) will not illuminate.
    •  The PCM will command a message to be displayed.
    •  The PCM may record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records.

Conditions for Clearing the Message/DTC

    •  The PCM will turn the message OFF after one run and pass of the diagnostic test.
    •  A History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using the scan tool Clear DTC Information function.

Diagnostic Aids

Since many things can cause a stalling condition use the snapshot taken of DTC P1599 to compare the values taken when the DTC set to the Typical Scan Data Value table. Look for conditions that could have caused the stall and how long ago the stall occurred.

DTC P1599 may be set if the engine speed drops below 400 RPM, near stall, and then recovers.

If the condition is intermittent, refer to Intermittent Conditions in Symptoms.

Test Description

The number below refers to the step number on the diagnostic table.

  1. If any other DTCs are set, diagnose those DTCs first.

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Are any other DTCs set?

--

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Symptoms