Diagnostic Instructions
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 swich 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
Connector End View Reference
Component Connector End Views
Description and Operation
Charging System Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References
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
.
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
