Code No.B1201:
Fuel information problem
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Whenever the ECU is replaced, ensure that the
communication circuit is normal.
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TROUBLE JUDGEMENT
With the ignition switch at the ON position and diagnosis code No. U1190 is not set, if
the combination meter detects the abnormal resistance of fuel level sensor circuit for 64 seconds continuously,
diagnosis code No. B1201 is set.
PROBABLE CAUSES
- Damaged harness wires and connectors
- Malfunction of fuel pump and gauge assembly
- Malfunction of combination meter
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STEP 1. Check of fuel pump and gauge assembly circuit
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(1)Disconnect the fuel pump and gauge assembly connector.
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(2)Use the special tool Check harness (MB991219) to connect a test lamp (12 V - 3.4
W) between the wiring harness connector terminals.
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(3)Turn the ignition switch to the ON position.
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(4)Check if the test lamp illuminates.
OK: Illuminates
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Q.
Is the check result normal?
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 Go to Step 6.
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 Go to Step 2.
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STEP 2. Fuel pump and gauge assembly check
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Check the fuel pump and gauge assembly (Refer to  ).
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Q.
Is the check result normal?
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Go to Step 3.
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Replace the fuel pump and gauge assembly. (Refer to GROUP 13D - Fuel
Tank ).
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STEP 3. Resistance measurement at the fuel pump and gauge assembly
connector
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(1)Disconnect the fuel pump and gauge assembly connector, the measure at the harness
side.
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(2)Measure the resistance between the fuel pump and gauge assembly connector (earth
terminal) and the body earth.
OK: Continuity exists (2 Ω or less)
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Q.
Is the check result normal?
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Go to Step 5.
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Go to Step 4.
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STEP 4. Check of open circuit in body earth line between fuel pump
and gauge assembly connector and body earth.
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Q.
Is the check result normal?
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Go to Step 7.
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Repair the connector(s) or wiring harness, and then go to Step 7.
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STEP 5. Check of open circuit in F/G line between combination meter
connector and fuel pump and gauge assembly connector.
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Q.
Is the check result normal?
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Go to Step 6.
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Repair the connector(s) or wiring harness, and then go to Step 7.
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STEP 6. M.U.T.-III actuator test
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- Item 03: Fuel gauge (target value): 0 →100%
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OK: The fuel gauge operates.
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Q.
Is the check result normal?
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Go to Step 7.
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Replace the combination meter (Refer to ).
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STEP 7. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set in the combination meter.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(3)Check if diagnosis code is set.
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Q.
Is the diagnosis code set?
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Replace the combination meter (Refer to ).
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The diagnosis is complete.
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