Glass, Frames and Mechanisms — 2016 workshop reference 1229

Inspect the rear window defrost grid and electrical connectors for damage.

PINPOINT TEST K : THE DEFROST SYSTEM IS INOPERATIVE

K1 CHECK THE REAR WINDOW DEFROST GRID VOLTAGE

Ignition OFF. Disconnect: Heated Rear Window Element C402A (coupe) or C402 (convertible). Ignition ON. Activate the rear window defrost switch. For coupe, measure:

Click to display connectors

Positive Lead	Measurement / Action	Negative Lead
C402A-1		Ground

For convertible, measure:

Click to display connectors

Positive Lead	Measurement / Action	Negative Lead
C402-1		Ground

Is the voltage greater than 11 volts?

Yes	GO to K2
No	GO to K3

K2 CHECK THE REAR WINDOW DEFROST GRID GROUND

Ignition OFF. Disconnect: For coupe, heated Rear Window Element C402B. For coupe, measure:

Click to display connectors

Positive Lead	Measurement / Action	Negative Lead
C402B-1		Ground

For convertible, measure:

Click to display connectors

Positive Lead	Measurement / Action	Negative Lead
C402-2		Ground

Is the resistance less than 3 ohms?

Yes	CARRY OUT the Grid Wire Test. REFER to Grid Wire Test. REPAIR the rear window defrost grid or INSTALL a new rear window glass. REFER to: Fixed Glass (501-11 Glass, Frames and Mechanisms, General Procedures).
No	REPAIR the circuit.

K3 CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR VOLTAGE

Ignition OFF. Disconnect: Rear Window Defrost Relay. Ignition ON. Measure:

Positive Lead	Measurement / Action	Negative Lead

Source reference 1229

2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.