B1428

DTC B1428

Circuit Description

The body control module (BCM) controls the ignition 1 (IGN 1) relay. The contacts of the IGN 1 relay deliver a B+ signal to the following components:

* The antilock brake system (ABS) functions
* The AC compressor relay
* The crank relay
* The HVAC control head
* The instrument panel cluster (IPC)
* The powertrain control module (PCM)
* The sensing and diagnostic module (SDM)
* The transmission solenoids

The BCM will energize the IGN 1 relay when the vehicle is in the RUN or CRANK power mode. The BCM supplies a B+ signal to the relays control circuit to energize it. The relays control circuit receives it's ground from G113. If a short or circuit malfunction takes place in the IGN 1 control circuit the BCM will set a B1428 and the relay will not energize.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1428 Ignition-Switched Power Relay Circuit

Conditions for Running the DTC

The ignition switch is in the RUN or CRANK position.

Conditions for Setting the DTC

* A DTC B1428 sets when the BCM detects a short to ground in the IGN 1 relay control feed circuit when it is trying to energize the IGN 1 relay.
* A DTC B1428 sets when the BCM detects an open in the IGN 1 relay control feed circuit when it is trying to energize the IGN 1 relay.
* The conditions above must be present for more than 0.3 second.

Action Taken When the DTC Sets

The BCM stores DTC B1428 in memory.

Conditions for Clearing the DTC

* A short to ground or a malfunction in the IGN 1 relay control feed circuit is no longer detected by the BCM.
* A history DTC B1428 will clear after the modules ignition counter reaches the reset threshold, without a repeat of the malfunction.

Diagnostic Aids

* If the DTC B1428 is a history DTC, the fault may be intermittent. refer to Testing for Intermittent Conditions and Poor Connections.
* The following conditions may cause an intermittent malfunction to occur:

- An intermittent short to ground in the IGN 1 relay control feed circuit
- The IGN 1 relay coil is shorted to ground internally.
- The BCM is shorted to ground internally.

Test Description

Step 1 - Step 12:

Step 13:

The numbers below refer to the step numbers on the diagnostic table.
2. Listen for an audible click when the IGN 1 relay operates. Command both the ON and OFF states. Repeat the commands, as necessary.
3. This step verifies that the BCM is providing voltage to the IGN 1 relay.
4. This step tests for an open in the ground circuit to the IGN 1 relay.
5. This step tests if voltage is constantly being applied to the IGN 1 relay.