For 1990-2009 cars

### Circuit Description

The keyless entry receiver is integrated within the body control module (BCM). A different signal from the transmitter is sent to the receiver when any of the four buttons are pressed on the transmitter. Each signal contains a message to execute a command (e.g., LOCK/UNLOCK drivers door). The receiver transforms the commands and transmits the message to the BCM, which will execute the requested command.

### Conditions for Setting the DTC

A message is received with the correct transmitter ID but the accompanying security information cannot be validated. A message validation counter is increased each time the receiver receives consecutive incorrect security information. When the counter reaches 16, a DTC B2560 is set.

### Action Taken When the DTC Sets

• | Stores a DTC B2560 in the receivers memory.

• | The message validation counter is reset.

• | Receiver operation is disabled for a minimum of 20 seconds.

### Conditions for Clearing the DTC

• | The current status of the DTC becomes a history status when a valid message is subsequently received.

• | The use of a scan tool.

### Diagnostic Aids

The following conditions may cause intermittent transmitter or receiver operation.

• | Transmitter battery terminals not clean.

• | Poor contact with transmitter battery terminals.

• | Out of range vehicle battery or ignition voltage. Normal voltage range is 9.0-16.0 V.

### Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. A weak battery may cause the transmitter to malfunction. After replacing the battery, the transmitter is synchronized.

2. After replacing the battery the transmitter is tested again to see if the DTC resets.

3. Both transmitters might be out of sync. This test reprograms both transmitters. After reprogramming, both transmitters are tested again.

4. If the DTC resets after both transmitters were reprogrammed, the most likely cause is the receiver within the BCM.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Keyless Entry Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Remote Keyless Entry
2 | Does this DTC set with one particular transmitter? | -- | Go to Step 3 | Go to Step 4
3 |

1. Replace the battery in the transmitter that set the DTC. Refer to Transmitter Battery Replacement .
2. Synchronize the transmitter. Refer to Transmitter Synchronization .

Did you complete the battery replacement and synchronization?

--

Go to Step 5

--

4 | Does the DTC set with both transmitters? | -- | Go to Step 6 | --
5 |

1. Install a scan tool.
2. Use the scan tool in order to clear the DTCs.
3. Operate the transmitter through all four button functions.
4. With the scan tool read DTCs.

Does the DTC reset?

--

Go to Step 7

Go to Step 8

6 |

1. Install a scan tool.
2. Use the scan tool in order to reprogram both transmitters. Refer to Transmitter Programming .
3. Operate both transmitters through all four button functions.
4. With the scan tool read DTCs.

Does the DTC reset with both transmitters?

--

Go to Step 9

Go to Step 8

7 | Replace and program the transmitter. Refer to Transmitter Programming . Is the replacement complete? | -- | Go to Step 8 | --
8 | Verify keyless entry operation. Using the transmitter, lock/unlock the doors, release the trunk lid and fuel filler door. Does the keyless entry system operate properly? | -- | System OK | --
9 | Replace the BCM. Refer to Body Control Module Replacement in Body Control System. Did you complete the replacement? | -- | Go to Step 8 | --