Pinpoint Test I : The Defrost System Is Inoperative - DATC (Dual Automatic Temperature Control): Notes

WARNING: This page is about a different car, the 2018 Ford Focus. However, it is still accessible from the selected car via links, so may be relevant.

Refer to Heated Window for schematic and connector information.

Normal Operation and Fault Conditions

REFER to: Glass, Frames and Mechanisms - Vehicles With: One-Touch Open Driver Window - System Operation and Component Description .

Possible Sources

Fuse(s)
Rear window defrost relay
Wiring, terminals or connectors
HVAC module
Isolator
Rear window defrost grid
BCM

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Conditions
B1C84:12	Heated Rear Window Relay Output: Circuit Short To Battery	This DTC sets when the BCM detects a short to voltage on the rear window defrost relay control circuit.
B1C84:13	Heated Rear Window Relay Output: Circuit Open	This DTC sets when the BCM detects an open in the rear window defrost relay control circuit.
B1C84:14	Heated Rear Window Relay Output: Circuit Short To Ground or Open	This DTC sets when the BCM detects a short to ground or an open in the rear window defrost relay control circuit.

Visual Inspection and Diagnostic Pre-checks

Verify BJB fuse 9 (30A) and 23 (5A) are OK.
Inspect the rear window defrost relay.
Inspect the rear window defrost grid and electrical connectors for damage.