Fuel Tank Pressure Sensor
The following procedure is used to diagnose the Fuel Tank Pressure (FTP) Sensor -G400- which is controlled by Engine Control Module -J623-.
Special tools and workshop equipment required
- multimeter.
- Wiring diagram.
Test requirements
- The Engine Component Power Supply Relay -J757- OK.
- The Fuse -SF2- OK.
- The fuel filter OK.
- The parking brake engaged.
- The battery voltage at least 12.5 V.
- The selector lever of automatic transmission in position "P" or "N".
- All electrical consumers switched off.
- A/C switched off.
- The fuel tank at least 1 /4 filled.
- The ignition switched off.
Test procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK.
Start diagnosis
Checking voltage
Crank the engine.
-- Using a multimeter, check the Fuel Tank Pressure (FTP) Sensor -G400- electrical harness connector terminal 1 to Ground (GND) for voltage.
Specified value: battery voltage.
-- Switch the ignition off.
If the specified value was not obtained:
-- Check the wiring from the Fuel Tank Pressure (FTP) Sensor -G400- electrical harness connector terminal 1 to the Engine Component Power Supply Relay -J757- socket 8/87 for an open circuit or a short circuit to Ground (GND).
-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
-- If necessary, repair the wiring connection.
If no malfunctions are found in the wiring:
Checking wiring connections
If the manufacturers test box is being used, perform the following step.
-- Install the test box.
If the manufacturers test box is not being used, perform the following step.
-- Remove the Motronic Engine Control Module (ECM) -J623-. Refer to appropriate Service Information.
-- Using a multimeter, check the Fuel Tank Pressure (FTP) Sensor -G400- electrical harness connector terminal to the Engine Control Module (ECM) -J623- electrical harness connector T94 terminal for resistance.
| Fuel Tank Pressure (FTP) Sensor -G400- electrical harness connector terminal | Engine Control Module (ECM) -J623- electrical connector T94 terminal or test box socket |
|---|---|
| 2 | 54 |
| 3 | 52 |
Specified value: 1.5 Ω Max.
If the specification was not obtained:
-- Check the wiring for an open circuit, a short circuit to each other, Battery (+) or Ground (GND).
-- If necessary, repair the faulty wiring connection.
If no malfunction is detected in the wiring:
-- Erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY.
-- Perform a road test to verify repair.
If the DTC does not return:
Repair complete, Generate readiness code. Refer to READINESS CODE.
-- End diagnosis.
If the DTC returns and no malfunction is found in the wiring and voltage supply was OK:
-- Remove the Motronic Engine Control Module (ECM) -J623-. Refer to appropriate Service Information.
Assembly is performed in the reverse order of the removal, note the following:
Final procedures
After repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY.
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY.
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE.