Signal Too Low

ECM-4020 FUEL TANK PRESSURE SENSOR
SIGNAL TOO LOW

Engine control module (ECM)
Reading off the status of the diagnostic trouble code (DTC):



Note! When reading off the DTC status, other stored diagnostic trouble codes (DTCs) and their status will also be listed.

- Start the engine. Let it idle for at least 15 seconds.
- Read off the diagnostic trouble code (DTC) status. Check the status of the relevant diagnostic trouble code (DTC).

Was the status of the relevant diagnostic trouble code (DTC) permanent?
Yes - Continue below.
No - Signal Too Low - Intermittent Fault


Checking wiring and connectors



Check the signal cable between engine control module (ECM) connector terminal #B31 (#B41) and fuel tank pressure sensor connector terminal #2 for an intermittent short-circuit to ground according to [1][2]Checking Wiring and Terminals. Permanent Fault

Check the signal cable between engine control module (ECM) connector terminal #B10 (#B20) and fuel tank pressure sensor connector terminal #3 for an intermittent short-circuit to ground according to [1][2]Checking Wiring and Terminals. Permanent Fault

Other information:
- For connection of engine control module (ECM) breakout box, Connecting the Breakout Box (ECM)
- To access/replace the fuel tank pressure sensor, Fuel Tank Pressure Sensor, Replacing
- Voltage supply for the fuel tank pressure sensor #3 is approximately 5V. #1 is ground and #2 is signal.
- For information about signals, Pinout Values and Diagnostic Parameters


Verification



Hint: After carrying out the repair, check that the fault has been remedied.
- Ignition off.
- Reinstall connectors, components etc. Read off fuel tank pressure.
- Start the engine and let it idle.
- Activate the EVAP canister shut-off valve and allow it to open.

Activate canister purge (CP) valve. Open and shut the valve. Read off the fuel tank pressure and check if the values have changed.

Hint: When the canister purge (CP) valve is open the pressure in the fuel tank drops.

Note! If the EVAP canister is full the engine may stop when canister purge (CP) valve activation occurs because of the extra fuel supply.

Does the tank pressure change?
Yes - Testing Complete.
No - Continue below.


Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.