GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1999 🢒 Catera 🢒 DTC 🢒 DTC P1523 Throttle Closed Position Performance

Circuit Description

The ECM monitors the positioning of the throttle blade.

When the throttle is unable to return to its stop in a calibratable time, this DTC will set.

Conditions for Running the DTC
    • The vehicle speed is equal to 0 km/h.
    • The engine speed is less than 250 RPM.
    • The engine coolant temperature (ECT) is between 5°C-100°C (41°F-212°F).
    • The intake air temperature (IAT) is more than 5°C (41°F).

Conditions for Setting the DTC

The engine control module (ECM) determines that the throttle body valve is not in the closed position.

Action Taken When the DTC Sets

The ECM illuminates the malfunction indicator lamp (MIL) and records the operating conditions in the Freeze Frame on the first drive trip that the diagnostic runs and fails.

The vehicle will default to the limp home mode.

Conditions for Clearing the MIL/DTC
    • The ECM turns off the MIL after 3 consecutive drive trips that the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive drive trips that the diagnostic runs and passes.
    • The ECM battery voltage is interrupted.
    • The scan tool clears the MIL/DTC.

Diagnostic Aids

Inspect for a condition in which the throttle valve may have been held open. Inspect for conditions in which ice may have formed in the throttle bore.

Notice: Using the J 35616-A Connector Test Adapter Kit will prevent damage to the harness connector terminals.

Use the J 35616 connector test adapter kit for any test that requires probing the ECM harness connector or a component harness connector.

Check for the following conditions:

    • Poor connections at the ECM or at the component--Inspect the harness connectors for a poor terminal to wire connection. Refer to Engine Control Module Diagnosis , Checking Terminal Contact, for the proper procedure.
    • Damaged harness--Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may help locate the fault.

Refer to Symptoms for the Intermittents.

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
  1. Turn the ignition ON leaving the engine OFF.
  2. Inspect the throttle valve.

Is the throttle valve completely closed?

--

Go to Step 3

Go to Step 5

3
  1. Clear DTC Information using the scan tool.
  2. Turn the ignition OFF and wait 30 seconds.
  3. Turn the ignition ON and inspect for DTCs.

Is this DTC set?

--

Go to Step 4

Go to Diagnostic Aids

4
  1. Turn the ignition OFF.
  2. Disconnect the ECM.
  3. Disconnect the TP sensor connector.
  4. Test the TP sensor circuits for the following:
    5. • opens
    • high resistance
    • shorts to ground
    • shorts to other circuits
    • Poor terminal contact at the ECM connector
  5. Repair the wiring as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found and repaired?

--

Go to Step 7

Go to Step 6

5

Replace the throttle body assembly. Refer to Throttle Body/Throttle Position Sensor Replacement .

Is the action complete?

--

Go to Step 7

--

6

Important: 

   • Perform the Idle Learn Procedure when replacing the ECM or the throttle body.
   • This vehicle is equipped with a theft deterrent system that interfaces with the engine control module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle.

Replace the ECM. Refer to Engine Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 7

--

7
  1. Use a scan tool in order to clear the DTCs.
  2. Start the engine.
  3. Allow the engine to idle until the engine reaches the normal operating temperature.
  4. Select DTC and the Specific DTC function.
  5. Enter the DTC number that was set.
  6. Operate the engine within the Conditions for Running this DTC until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

--

Go to Step 8

Go to Step 2

8

Does the scan tool display any additional, undiagnosed DTCs?

--

Go to the applicable DTC table

System OK