Rear window defroster doesn't heat up

Symptoms

• Defroster button lights up but glass doesn't warm
• No condensation clearing from the rear window
• A visible scratch or break in one of the thin horizontal lines
• Defroster worked until recently, possibly after cleaning the glass

Likely causes

• CommonBlown rear defroster fuseA dedicated fuse for this feature can blow independently of other electronics.
• CommonBroken heating grid line on the glassThe thin lines on the rear glass are the actual heating element and can break from scraping ice or cleaning too hard.
• PossibleFaulty defroster relayThe relay controlling power to the defroster can fail.
• PossibleLoose connector at the edge of the glassThe connectors where the defroster grid meets the wiring harness can corrode or loosen.

What to do

1. Check the fuse box for a blown rear defroster fuse and replace with the correct amperage.
2. Look closely at the horizontal lines on the rear glass for any visible breaks or scratches.
3. Feel the glass a minute or two after activating the defroster to see if any sections warm up at all.
4. Check the small connectors at each end of the grid lines (usually visible at the edges of the glass) for looseness.
5. If only part of the grid isn't heating, a specific line break can sometimes be repaired with a conductive repair kit.
6. Avoid scraping the inside of the rear window with hard tools, which can damage the heating lines.
7. Have a shop test the defroster relay and connections if the fuse and visible lines look fine.
8. Consider a defroster grid repair kit for minor breaks, or glass replacement if damage is extensive.

Tools and parts

• Fuse puller or pliers
• Replacement fuses
• Multimeter (optional)

When to call a pro

If the break in the grid line is large or in a hard to reach spot, or if multiple lines are affected, glass replacement may be more practical than a repair kit.

Safety