Tank Pressure Sensor - Inspecting and Replacing
SECTION2
GROUP
23
NO.
818
DATE
Nov. -95
Inspecting and replacing tank pressure sensor
800
REFERENCE: TP 2308201, SECTION 2 (23, 28), SFI ENGINE MANAGEMENT SYSTEM; MOTRONIC 4.4; 850 1996-
Inspecting and replacing tank pressure sensor
If the control module receives a signal from the tank pressure sensor corresponding to a pressure over 2.95 kPa (61.6 lbf/sq.ft)(high signal) or below -2.88 kPa (-60.1 lbf/sq.ft) (low signal) diagnostic trouble code (DTC) EFI-621 Tank pressure sensor, signal is posted.
Replacement values:
- leakage diagnostic is turned off.
Causes of fault:
Signal too high:
- signal cable short-circuit to supply voltage
- open-circuit in signal or ground cable
- contact resistance in connectors
- defective tank pressure sensor
Signal too low:
- signal cable short-circuit to ground
- A/C pressure sensor power cable short-circuit to ground
- accelerometer power cable short-circuit to ground
- open-circuit in signal cable
- open-circuit in power cable
- power cable short-circuit to ground
- contact resistance in connectors
- defective tank pressure sensor
Fault symptoms:
- none.
X1
Diagnostics:
Status message
^ permanent fault, signal too high, trace fault according to X2.
^ permanent fault, signal too low, trace fault according to X4.
^ intermittent fault, signal too high, trace fault according to X6.
^ intermittent fault, signal too low, trace fault according to X7.
X2
Permanent fault, signal too high:
Checking ground lead
- ignition off
- wait 150 seconds.
- disconnect tank pressure sensor
Connect an ohmmeter between tank pressure sensor connector terminal 2 (to the control module) and ground.
The ohmmeter should read approx. 0 Ohm
If the reading is OK
Check the signal cable X3.
If the reading not OK:
Check cable between tank pressure sensor terminal 2 and control module # B28 via connector 24/4 terminal E6 and connector 24/2 terminal C7 for an open-circuit according to KA2.
X3
Checking signal cable
- tank pressure sensor disconnected
- ignition on.
Connect a voltmeter between tank pressure sensor connector terminal 3 (to the control module) and ground.
Voltmeter should read approx. 6 V.
If the reading is OK:
Try a new tank pressure sensor, see method on page 5.
If the voltmeter reads approx. 12 V:
Check cable between tank pressure sensor terminal 3 and control module # B31 via connector 24/4 terminal E5 and connector 24/2 terminal C6 for a short-circuit to supply voltage according to KA4.
If the voltmeter reads approx. 0 V:
Check cable between tank pressure sensor terminal 3 and control module # B31 via connector 24/4 terminal E5 and connector 24/2 terminal C6 for an open-circuit according to KA2.
X4
Permanent fault, signal too low
Checking power cable
- ignition off
- disconnect tank pressure sensor
- ignition on.
Connect a voltmeter between tank pressure sensor connector terminal 1 (to the control module) and ground.
Voltmeter should read approx. 5 V.
If the reading is OK:
Check signal cable X5.
If the reading not OK:
- Check cable between tank pressure sensor terminal 1 and control module # B15 via connector 24/4 terminal E4 and connector 24/2 terminal C5 for an open-circuit according to KA2 and short-circuit to ground according to KA3.
- Check cable between accelerometer terminal 1 and control module # B1 for short-circuit to ground according to KA3.
- Check cable between A/C pressure sensor terminal 3 and control module # B29 for short-circuit to ground according to KA3.
X5
Checking signal cable
- tank pressure sensor disconnected
- ignition on.
Connect a voltmeter between tank pressure sensor connector terminal 3 (to the control module) and ground.
Voltmeter should read approx. 6 V.
If the reading is OK:
Try a new tank pressure sensor see Replacing Tank.
If value not OK:
Check cable between tank pressure sensor terminal 3 and control module # B31 via connector 24/4 terminal E5 and connector 24/2 terminal C5 for an short-circuit to ground according to KA3.
X6
Intermittent fault, signal too high
Checking cabling and connections
- Check tank pressure sensor and control module connectors as well as connectors 24/2 and 24/4 for loose connections according to KA5 and contact resistance and oxidation according to KA6.
- Check cable between tank pressure sensor terminal 3 and control module # B31 via connector 24/4 terminal E5 and connector 24/2 terminal C5 for an intermittent short-circuit to supply voltage according to KA4 and an intermittent open-circuit according to KA2.
- Check cable between tank pressure sensor terminal 2 and control module # B28 via connector 24/2 terminal E5 and connector 24/2 terminal C7 for an intermittent open-circuit according to KA2.
- Try a new tank pressure sensor.
X7
Intermittent fault, signal too low
Checking cabling and connections
- Check tank pressure sensor and control module connectors as well as connectors 24/2 and 24/4 for loose connections in accordance with KA5 and contact resistance and oxidation according to KA5.
- Check cable between tank pressure sensor terminal 3 and control module # B31 via connector 24/4 terminal E5 and connector 24/2 terminal C5 for an intermittent open-circuit in accordance with KA2 and an intermittent short-circuit according to KA3.
- Check cable between tank pressure sensor terminal 1 and control module #B15 via connector 24/4 terminal E4 and connector 24/2 terminal C5 for an intermittent short-circuit to ground according to KA3.
- Check cable between accelerometer terminal 1 and control module # B1 for an intermittent short-circuit to ground according to KA3.
- Check cable between A/C pressure sensor terminal 3 and control module # B29 for an intermittent short-circuit to ground according to KA3.
- Try a new tank pressure sensor see method.
TF Replacing tank pressure sensor
Special tools: 999 5972
TF1
Preparations
Wagon:
- Remove all floor hatches and fold back carpet.
- Remove the cover over the pump unit.
Sedan:
- Fold down right rear seat.
- Remove trunk carpet.
- Fold back corner of wheel arch panel by shock absorber mounting.
- Remove the cover over the pump unit.
TF2
Removing connectors
- Disconnect all connectors on the bracket.
- Remove rubber bracket around cables.
- Ensure that cables passing through the hole by the pump unit are free and are not obstructed when the tank is lowered.
TF3
Removing filler pipe
- Remove compression lock ring over rubber seal.
- Remove rubber seal from body.
TF4
Removing fuel tank
- Position mobile jack with fixture 999 5972 under the tank, ensure that the lifting platform is flat to avoid damaging the tank.
- Release tank retaining straps and lower tank slightly
TF5
Removing front mounting
- Remove the entire mounting from the bracket by pulling it towards the right of the car.
TF6
Installing a new tank pressure sensor.
- Remove the old tank pressure sensor.
- Install the new tank pressure sensor route cabling as before.
NOTE:
It is important to install the tank pressure sensor hose correctly to avoid leakage.
TF7
Installing fuel tank
- Raise the tank sufficiently so that the front mounting can be mounted on the bracket.
- Route cables through the hole by the pump unit so that they are not obstructed when the tank is installed.
- Raise the tank and mount onto the body
TF8
Installing rubber seal on filler pipe.
- Check that the inner seal is correctly seated and that the drain tube is inside the inner seal.
- Check the position of ring (1).
- Oil the rubber seal/filler pipe sealing surface (2).
- Install the rubber seal (ensure that it is the right way round).
- Install ring (4) and drain pipe (3).
- Connect fuel pump and level sensor connectors. Tank pressure sensor and ABS sensors.
- Install rubber bracket around cabling.
- Reinstall panels, covers and carpets.