Body, generic

B0237 Backup Lamp Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Neither the publicly available J2012 lists nor any public service literature mention B0237, so it remains unconfirmed. In the words of FMVSS 108, backup lamps light the road behind the car and warn pedestrians and drivers that it is reversing or about to. HELLA notes that the circuit may only be live with the ignition on and reverse engaged. Manual gearboxes close a plunger switch in reverse; on automatics the range sensor or the transmission controller supplies the signal. In patent US5065135A, held by Automotive Products, logic that decodes the selector position energises a relay feeding the lamp for as long as reverse is reported. A fault leaves the lamps dark in reverse, or lit outside reverse when the line is shorted to supply.

Likely causes

Reverse light switch on the gearbox worn or its plug corroded by road spray
Reversing lamp bulb burnt out or LED unit failed
Missing reverse signal from the range sensor or transmission module on automatics
Broken wire in the tailgate harness feeding the lamp

Symptoms

  • Reversing lamps stay dark with reverse gear engaged
  • Reversing lamps lit while driving forward

Repair estimate

DifficultyEasyDIY possible
Parts and labour€10–180
Time0.2–1.5 h

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

Parts involved

backup lampreverse switchbody wiring harness

Related codes

B0239B0235

References: law.cornell.edu, hella.com, patents.google.com.