GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 Body and Accessories 🢒 Theft Deterrent 🢒 DTC B2780 Wrong Resistor Before Good

Object Number: 333545 Size: MF
Instrument Cluster: Analog Schematics

Circuit Description

When a key is inserted into the ignition switch, the terminals located in the steering column lock cylinder contact the resistor pellet in the ignition key. The IPC measures the resistance of the key pellet and then compares the resistance to the one stored in the IPCs memory.

Conditions for Setting the DTC

The IPC determines that one of the 15 valid key pellets was detected, but the current key pellet resistance value does not match the resistance of the one stored in the IPCs memory.

Action Taken When the DTC Sets

The IPC displays the STARTING DISABLED, DUE TO THEFT SYSTEM, REMOVE IGNITION KEY message on the driver message center and prevents the vehicle from starting. The IPC then starts the 3 minute delay sequence with messages.

Diagnostic Aids

If this DTC is set as current, the vehicle ignition switch may have been tampered with. Ensure that all ignition keys for the vehicle are available and that every key sets the same malfunction DTC code.

Step

Action

Yes

No

1

Did you perform the Theft Deterrent Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2
  1. Install a scan tool.
  2. Turn ON the ignition with the engine OFF.
  3. Select the Display DTCs function for the IPC.

Does the scan tool display DTC B2780 as a current DTC?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3

Does the scan tool display DTC B2710 or B2711 as a current DTC?

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Step 4

4

Inspect the ignition key for dirt or obvious damage.

Does the ignition key appear dirty or damaged?

Go to Step 11

Go to Step 5

5
  1. Turn off the ignition.
  2. Disconnect connector C202. (Note which half of the connector is the vehicle harness side and which half of the connector is the steering column harness side.
  3. Back out the terminals for the key resistor input circuit and key resistor reference ground circuit from the vehicle harness side of the connector.
  4. Reconnect C202.
  5. Connect a J 35628-A Vats/Passkey Interrogator using terminal adapters from a J 35616 to the key resistor input circuit and key resistor reference ground circuit.
  6. Note: This step may take as long as 45 minutes due to a trial and error process. Turn the rotary switch on the J 35628-A to each code number (1-15) and attempt to start the vehicle with each code number. (After each failed starting attempt, you must wait 3 minutes before the next attempt.)

Does the vehicle start with one of the codes selected on the J 35628-A?

Go to Step 6

Go to Step 7

6
  1. Note the code number on the J 35628-A that successfully started the vehicle.
  2. Obtain and cut a new ignition key with the correct key code value.
  3. Attempt to start the vehicle with the new ignition key.

Does the vehicle start?

Go to Step 14

Go to Step 8

7

Test the following circuits in the vehicle harness portion for an open or a short:

    • The key resistor input circuit
    • The key resistor reference ground circuit

Was a condition found and corrected?

Go to Step 14

Go to Step 10

8

Test the following circuits in the steering column harness portion for an open or a short:

    • The key resistor input circuit
    • The key resistor reference ground circuit

Was a condition found and corrected?

Go to Step 14

Go to Step 9

9

Inspect for poor connections at the harness connector of the ignition lock cylinder. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 12

10

Inspect for poor connections at the harness connector of the instrument cluster. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 13

11

Clean or replace the ignition key as necessary. Refer to Programming Replacement Keys, Ignition Cylinder, or Powertrain Control Module .

Did you complete the procedure?

Go to Step 14

--

12

Replace the ignition lock cylinder. Refer to Steering Column Lock and Ignition Switch Cylinder Replacement - On Vehicle in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 14

--

13

Replace the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.

Did you complete the repair?

Go to Step 14

--

14
  1. Use the scan tool in order to clear the DTCs.
  2. Attempt to start the vehicle.

Does the DTC reset?

Go to Step 2

System OK