Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC B1428: Ignition-Switched Power Relay 1 CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Ignition 1 Voltage | B1428 | B1428 | 1 | -- |
Ground | -- | B1428 | -- | -- |
1. DTC B1428 may or may not set for a short to voltage depending on the ignition key position when the short occurred. | ||||
Circuit Description
The body control module (BCM) controls the IGN 1 Relay which is located in the underhood fuse block. The switch contacts of the 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 relay when the vehicle is in the RUN or CRANK power mode. The BCM supplies B+ on the ignition 1 voltage circuit (control circuit) to energize the relay. The relay ground circuit is from G113. If a short or open/high resistance in the ignition 1 voltage circuit or an open in the ground circuit occurs, the BCM will set a B1428 and the relay will not energize.
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 ignition 1 voltage circuit of the relay when the output is controlled active. |
| • | A DTC B1428 sets when the BCM detects an open in the ignition 1 voltage circuit of the relay when the output is inactive. |
| • | The conditions above must be present for more than 0.3 second. |
Action Taken When the DTC Sets
The BCM stores DTC to memory.
Conditions for Clearing the DTC
| • | A current DTC clears on the next malfunction-free cycle. |
| • | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction. |
Diagnostic Aids
A history DTC maybe caused by an intermittent condition. Refer to Testing for Intermittent Conditions and Poor Connections .
Reference Information
Schematic Reference
| • | Engine Controls Schematics for the 3.8L engine |
| • | Engine Controls Schematics for the 3.6L engine |
Connector End View Reference
Master Electrical Component List
Description and Operation
Power Mode Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, disconnect the IGN 1 Relay 37.
- Test for less than 1 ohm of resistance between the ground circuit terminal C7 and ground.
- Connect a test lamp between the ignition 1 voltage circuit terminal A8 and ground.
- Command the Ignition Power Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If all circuits test normal, test or replace the IGN 1 relay.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp is always ON, test the ignition 1 voltage circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for module replacement, setup, and programming |
