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. Component Tests and General Diagnostics
- 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. Component Tests and General Diagnostics

TEST DESCRIPTION

Step 1 - 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.