Body, generic

B0490 Display Backlight Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

B0490 is not listed in any accessible J2012 source, nor does a carmaker's literature cover it, so public proof is lacking. The title covers the backlight of a display, today usually LED strings fed by a boost driver. TI's LP8866-Q1 and LP8872-Q1 flag open strings, shorted LEDs and LED shorts to ground and report them to the host; TI adds that quick short-to-ground detection avoids glare that could blind the driver at night. GM's 2011 9-4X logs B1289 when the radio finds the PWM brightness line to the rear-seat screens open or shorted 400 ms after enabling it, and the screens then fall back to a fixed brightness. A dark screen whose picture is still faintly visible in sunlight points here rather than to B0455.

Likely causes

LED string or single LED of the backlight failed
Backlight driver or its boost stage defective
Brightness control line open or shorted

Symptoms

  • Screen dark although content is faintly visible in bright light
  • Brightness cannot be adjusted or follows no day/night change
  • Uneven, flickering or partly dark backlight

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€150–1,200
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

display modulebacklight circuit

Related codes

B0455

References: ti.com, ti.com, ti.com, saabwisonline.com.