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Home >> Mercedes Benz >> 2001 >> ML430 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1178: Oil Sensor (B40), Oil Level Implausible >> Testing Procedure

Testing Procedure

  1. Oil Sensor Signal (Testing With Oscilloscope) -  Connect oscilloscope between ME-SFI control module connector "E" terminals No. 16 and 17 (socket box terminals No. 72 and 73). Turn ignition on. Adjust oscilloscope to measuring range 2 volts and time range to 50 milliseconds. Observe oscilloscope. See SIGNAL PATTERN IDENTIFICATION  . If oil sensor signal is okay, go step  3 . If oil sensor signal is not okay, possible causes are voltage supply problem, oil level, oil quality, wiring harness failure or oil level sensor (B40) defective. Repair as necessary. To check voltage supply, go to step  3 .
  2. Oil Sensor Signal (Testing With DVOM) -  Connect DVOM between ME-SFI control module connector "E" terminals No. 16 and 17 (socket box terminals No. 72 and 73). Turn ignition on. Observe DVOM. Voltage should suddenly rise (.3-3 volts). If oil sensor signal is okay, go next step. If oil sensor signal is not okay, possible causes are voltage supply problem, oil level, oil quality, wiring harness failure or oil level sensor (B40) defective. Repair as necessary. To check voltage supply, go to next step.
  3. Voltage Supply -  Connect DVOM between ME-SFI control module connector "E" terminals No. 16 and 15 (socket box terminals No. 72 and 71). Turn ignition on. Observe DVOM. Voltage should be 4.7-5.3 volts. If voltage is okay, test is complete. If voltage is not okay, possible cause is ME-SFI control module (N3/10) defective. Repair as necessary.
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