B1527

DTC B1527

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC B1527 00
- High Parasitic Load

Circuit/System Description

The body control module (BCM) monitors the state of charge (SOC) of the electrical system. If the BCM senses that the current draw was greater than 2 amps and the SOC at key-on is 30 percent lower than it was when the engine was last running, DTC B1527 00 will set.

Conditions for Running the DTC

The ignition is turned from OFF to Accessory or Run.

Conditions for Setting the DTC

* The SOC at key-on is 30 percent lower than when the engine was last running.
* The battery drain is more than 2 amps.

Action Taken When the DTC Sets

No actions are taken. This DTC serves only as an aid to the technician.

Conditions for Clearing the DTC

* The DTC will clear when the SOC is greater than or equal to 80 percent.
* A history DTC clears after 50 consecutive ignition cycles that the diagnostic runs and does not fail.

Diagnostic Aids

* This DTC indicates that the cause of a discharged battery is likely a parasitic current draw, rather than a defective battery.
* If the vehicle is equipped with an auxiliary battery (TP2), verify that there is not a fuse installed in the STUD 1 Fuse 70 position of the underhood fuse block. A plastic plug may be installed in this position instead of a fuse. If a fuse is installed in this position and any optional equipment is powered by the auxiliary battery, it will discharge the primary battery in addition to the auxiliary battery.
* Verify that all accessories are turned OFF, including optional accessories that the vehicle may have been wired for, but does not have installed, such as auxiliary lights. If an optional accessory switch is left in the ON position, it may energize a relay that will discharge the battery over time, even if the accessory is not installed on the vehicle.
* A battery discharging for no apparent reason while the vehicle is parked can be caused by an intermittent draw, such as a module waking up, or a continuous draw, such as a dome light or stuck relay. Look and listen for any components that may be operating when they should turn off, such as a fuel pump.

Reference Information
Schematic Reference

* Starting and Charging Schematics (Electrical Diagrams)
* Auxiliary Battery Schematics (Auxiliary Battery Schematics) (TP2)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Charging System Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Ignition ON, compare the scan tool BCM Prev. State of Charge and Start Up State of Charge parameters. The readings should not differ by more than 30 percent.

Circuit/System Testing

Refer to Battery Electrical Drain/Parasitic Load Test (Component Tests and General Diagnostics).

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.