B2528

DTC B2528 Horn Relay Circuit:

DTC B2528 Horn Relay Circuit (Part 1 Of 2):

DTC B2528 Horn Relay Circuit (Part 2 Of 2):

CIRCUIT DESCRIPTION
The horn circuit is part of a standard born system except for the Body Control Module (BCM) providing a control circuit. The BCM grounds circuit 28, energizing the relay and turning ON the horns, allowing them to be used for alarm functions. The BCM monitors the voltage level on the born control circuit. When the BCM commands the horn relay on, the voltage level on the control circuit should be low, and when off it should be high.
If the BCM detects a short to voltage in circuit 28 when attempting to activate the horn during an alarm function, a fault condition is present and a DTC will set.

CONDITIONS FOR SETTING THE DTC
^ BCM detects a high voltage level (i.e, short to voltage or BCM shorted to voltage internally) in the horn control circuit (circuit 28).
^ The BCM can only test for this condition when the BCM attempts to energize the horn relay during an alarm activation.
^ All conditions must be present for more than 0.08 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ Stores a DTC B2528 in the BCM memory.
^ No driver warning message will be displayed for this DTC.
^ The BCM turns off its output to the horn relay.

CONDITIONS FOR CLEARING THE DTC
^ When the ignition switch is rotated from the OFF position to the RUN position, a current DTC B2528 is always cleared. If a short to voltage is still present in circuit 28 when the BCM attempts to ground circuit 28 during an alarm function, DTC B2528 will reset as a current DTC.
^ A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
^ Using a scan tool.

DIAGNOSTIC AIDS
^ The following conditions may cause an intermittent malfunction to occur:
- An intermittent short to voltage in circuit 28.
- BCM shorted to voltage internally.
- Horn relay coil shorted to voltage internally.
^ If the BCM is shorted to voltage internally, or if circuit 28 is shorted to voltage, the horn will remain off at all times.
^ If the DTC is a history DTC, the problems may be intermittent. Try performing the tests shown while moving wiring and connectors, this can often cause the malfunction to appear.
^ DTC P1626 will set in the Powertrain Control Module (PCM) when the ignition switch is in the RUN position with the BCM disconnected.

TEST DESCRIPTION
Numbers below refer to the step numbers on the diagnostic table.
1. Always perform the BCM Diagnostic System Check before attempting to diagnose a DTC B2528.
2. Checks for a short to voltage in circuit 28.
3. Determines whether the short to voltage is in the Underhood (UH) electrical center or in circuit 28.
4. Cheeks the coil side of the horn relay for proper resistance values.
5. Clears DTCs and rechecks the system for DTC B2528 to reset.