Riviera V6-231 3.8L VIN C SFI (1989)
Body Control Module: Initial Inspection and Diagnostic Overview
Fuel Level Is Low
Fuel Level Low Message
DESCRIPTION:
The ignition 1 fuse #14 supplies the fuel gauge (CKT 239) and fuel level reference (CKT #39) circuits with system voltage. When the fuel tank is full
there should be system voltage present at pin 2B8 (CKT #30) or the BCM, and when the fuel tank is empty pin 2B8 (CKT #30) should be grounded. The
voltage at pin 2B8 of he BCM should decrease as the fuel tank level goes from full to empty. A fuel level reference voltage, at pin 3D7 (CKT #39) of the
BCM, is received by the BCM from the same ignition 1 source as the fuel level sensor. The BCM will then create a ratio between the fuel level reference
voltage (pin 3D7) and the fuel level sensor voltage (pin 2B8) to determine how much fuel is in the tank. The BCM will then send the averaged
calculated amount of fuel to the IPC to be displayed as gallons or liters or fuel remaining in the fuel tank. When the averaged calculated fuel level
reaches 1.9 gallon the BCM will send the "FUEL LEVEL IS LOW" message to the CRT.
TEST CONDITIONS:
Ignition 1 voltage is present.
FAILURE CONDITIONS:
Calculated fuel level laess than 1.9 gallons.
ACTION TAKEN:
1.
Display the "FUEL LEVEL IS LOW" message on the CRT.
2.
Flash lowest bar of fuel gauge.
3.
Turn on the "See Diagnostic Center" indicator on the IPC.
