GM Service Manual Online
For 1990-2009 cars only

Refer to Engine Controls Schematic

AIR Motor, AIR Valve, AIR Relay and Theft Deterant Module


Object Number: 588221  Size: FS
Underhood Accessory Wiring Junction Block, Secondary Air Injection PUmp Relay, Secondary Air Injection Valve Solenoid, Supercharger Bypass Valve, Heated Oxygen Sensors, MAF and EVAP
Underhood Accessory Wiring Junction Block, Secondary Air Injection PUmp Relay, Secondary Air Injection Valve Solenoid, Supercharger Bypass Valve, Heated Oxygen Sensors, MAF and EVAP
G101
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Engine Controls Components
Powertrain Control Module Description
HUD, Trip Calculator, I/P, BCM, CCM and VSS
HO2S #1 and HO2S #2
OBD II Symbol Description Notice
.

Circuit Description

The theft deterrent control module produces the theft deterrent fuel enable signal when ignition is ON and the proper transponder key value is detected. The powertrain control module (PCM) monitors the fuel enable signal during crank. If the proper signal is present on the theft deterrent fuel enable circuit, the PCM enables fuel delivery to allow the engine to start. If the PCM detects that the fuel enable signal is not present, or that the signal is incorrect while an attempt is made to start the engine, DTC P1629 will set. For further information on the content theft deterrent system, refer to .

Conditions for Running the DTC

    • DTC P1626 is not present.
    • An attempt is made to start the engine.

Conditions for Setting the DTC

    • The PCM detects an incorrect signal on the Theft Deterrent Fuel Enable Circuit.
    • The above conditions are present for longer than 2 seconds.

Action Taken When the DTC Sets

The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.

Conditions for Clearing the MIL/DTC

    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The history DTC clears after 40 malfunction free warm-up cycles.
    • The PCM receives a clear code command from the scan tool.

Diagnostic Aids

Inspect for the following:

Many situations may lead to an intermittent condition. Perform each inspection or test as directed.

Important: :  Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

    • Loose terminal connection
       -  Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
       -  Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
    • Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
    •  Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.

Test Description

Numbers below refer to the step numbers on the Diagnostic Table:

  1. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

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

Important: :  Before continuing diagnosis, ensure that the vehicle battery is fully charged.

Attempt to start the engine.

Does the engine crank?

--

Go to Step 3

Go to Diagnostic System Check - Engine Electrical in Engine Electrical

3

  1. Turn off the ignition switch.
  2. Disconnect the Theft Deterrent Module.
  3. Turn on the ignition switch.
  4. Using a DMM, measure voltage between the vehicle theft deterrent fuel enable circuit and the ground circuit at the Theft Deterrent Module harness connector.

Does voltage measure near the specified value?

5.0V

Go to Step 4

Go to Step 6

4

  1. Turn off the ignition switch.
  2. Reconnect the Theft Deterrent Module
  3. Turn on the ignition switch.
  4. Using DMM, probe the Theft Deterrent Module connector to measure frequency between the vehicle theft deterrent fuel enable circuit and ground.

Is the frequency between the specified values?

40-60 Hz

Go to Step 5

Go to Step 8

5

  1. Turn on the ignition switch.
  2. Clear DTC P1629.
  3. Attempt to start the vehicle.

Does the vehicle start and continue running?

--

Go to Diagnostic Aids

Go to Step 7

6

Test the vehicle theft deterrent fuel enable circuit for an open, short to ground, or short to voltage. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

7

Check the theft deterrent fuel enable circuit for a poor connection Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

8

  1. Inspect for poor connections at the BCM.
  2. If a problem is found, replace loose terminals. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Diagnostic System Check - Theft Deterrent in Theft Deterrent

9

Important: :  The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Did you complete the repair?

--

Go to Step 10

--

10

  1. Clear DTCs.
  2. Observe VTD Fuel Disable on the scan tool while cranking the engine.

Does VTD Fuel Disable display Active?

--

Go to Step 2

System OK