GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The PASS-Key® III (VTD) module sets code B2955 if the ignition key data is illegitimate.

Conditions for Setting the DTC

DTC B2955 indicates that the VTD module detected illegitimate ignition key data.

This condition could be caused by:

    • An ignition key with no transponder pellet or a transponder pellet that can not be read.
    • A VTD module key reader malfunction.

Action Taken When the DTC Sets

    • The VTD module enters the fail enable mode and allows the vehicle to start and run.
    • The VTD module stores a DTC B2955 in memory.
    • The PASS-KEY telltale will be illuminated.

Conditions for Clearing the DTC

    • The conditions for the fault are no longer present.
    • A history DTC will clear after 100 consecutive ignition cycles if the condition for the fault is no longer present.
    • The use of the scan tool.

Diagnostic Aids

This code may indicate an internal processor malfunction.

Inspect the ignition key for any obvious problems.

Before replacing the PASS-Key® III module, clear the codes with the scan tool and retest the module.

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. Verifies the condition for setting DTC B2955 is current.

  2. The key must be a PASS-Key®III transponder key with an operating transponder for the system to work.

  3. The only method to confirm whether the transponder in the key or the VTD (PASS-Key®III) module is malfunctioning is to try a alternative component in the system. The vehicle was delivered with 2 keys.

  4. The possibility is unlikely that more than one key will be defective. If all keys do not work, the VTD (PASS-Key®III) module must be malfunctioning.

  5. If the vehicle has a malfunctioning VTD (PASS-Key®III) module that malfunctioned during an ignition cycle, the system will be "fail enabled" and the vehicle will start for all keys.

  6. If a new key must be tried, the key must have the proper mechanical cut and the VTD (PASS-Key ®III) module must "learn" the transponder value.

  7. If only one key was available for the vehicle and the replacement key does not work, the VTD (PASS-Key®III) module must be malfunctioning.

Step

Action

Yes

No

1

Did you perform the Pass-Key Diagnostic System Check?

Go to Step 2

Go to PASS-Key Diagnostic System Check

2

Is DTC B2955 set as a current code?

Go to Step 3

Go to Intermittents and Poor Connections Diagnosis in Wiring Systems

3

Inspect the vehicle's key for damage to the molded head and for PK3 embossed on the shank.

Is the head of the key damaged or missing the PK3 embossing?

Go to Step 7

Go to Step 4

4

Are more than one of the vehicles keys available?

Go to Step 5

Go to Step 7

5

  1. Attempt to start the vehicle using all of the vehicle's available keys.
  2. Using a scan tool, observe for any VTD DTCs.

Do any of the available keys start the vehicle?

Go to Step 6

Go to Step 9

6

Do all of the available keys cause DTC B2955 to set?

Go to Step 9

Go to Step 7

7

  1. Replace the damaged/inoperative/suspect key.
  2. Copy the mechanical cut of the available key on a pass key III replacement key.
  3. Perform the Learn More Keys Mode procedure if a learned master key is available. If a learned master key is not available perform the All Keys Lost procedure. Refer to Programming Theft Deterrent System Components .

Is the replacement completed?

Go to Step 8

--

8

Does the replacement key cause DTC B2955 to set?

Go to Step 9

Go to Step 10

9

  1. Replace the Pass Key III module. Refer to PASS-Key III Module Replacement .
  2. Perform the Pass-Key Programming procedure. Refer to Programming Theft Deterrent System Components .

Is the replacement complete?

Go to Step 10

--

10

Important: If an All Keys Lost Procedure was performed, all keys not learned at that time have been erased and will not be recognized. Perform the Learn More Keys Mode procedure or instruct the customer on how to perform the Learn More Keys Mode procedure. Refer to Programming Theft Deterrent System Components .

  1. Use a scan tool in order to clear the DTCs
  2. Attempt to start the vehicle.

Does the DTC reset?

Go to Step 2

System OK