Component Tests

 CAUTION: During in-vehicle tests, do not let tester terminal studs designated by arrows come in contact with vehicle ground. The gauge will be shorted to the ground, preventing an accurate test and possibly damaging the gauge.

1. Disconnect connector from the appropriate sender and hook onto the matching terminals on the tester.

2. Turn the vehicle ignition switch lock cylinder (11582) to ON position.

Fuel Gauge, F-150, F-250, F-350

If only the fuel gauge is inoperative or appears to be out of calibration, a calibration test can be conducted on the vehicle fuel gauge system.

Fuel Tank Sending Unit

With the sending unit float arm in the empty stop position, resistance should be 15 ohms (below E). With the sending unit float arm in the full stop position, resistance should be 160 ohms (above F). The fuel gauge should read empty at 22.5 ohms and full at 145 ohms.

Fuel Tank Second Sending Unit Test, F-Series Dual Tanks

On F-Series aft/axle (standard) fuel tank (9002), the fuel sender electrical connector can be disconnected and attached to a second test sender outside the fuel tank. The float can then be manually operated (up and down) while the fuel gauge operation is observed. Proper gauge function indicates a problem with the fuel tank sending unit located in the fuel tank. Improper operation indicates a problem with the fuel tank gauge or wiring. Refer to Pinpoint Test A in this section.

Fuel Tank Damage

If fuel indicating system components are functioning properly and inaccurate indications continue, check the fuel tank for damage which may have changed the fuel tank sending unit mounting angle and/or damaged the fuel tank sending unit. Make sure the fuel delivery module (FDM) is the correct model for the vehicle and that the FDM is not contacting the bottom of the fuel tank. Also inspect the vent hoses for kinks or obstructions.

Coolant Temperature Gauge

Check gauge calibration as follows:

• Using a Rotunda Instrument Gauge System Tester 014-R1063 or equivalent, with the key in the OFF position, disconnect wiring connector at the sender and connect tester to wiring connector.
• Set the tester to 74 ohms.
• Turn the key to RUN, and wait 60 seconds. The gauge should indicate on the COLD graduation.
• Set the tester to 9.7 ohms and wait 60 seconds. The gauge should indicate on the HOT graduation.

• If engine coolant temperature gauge tests within calibration, replace engine coolant temperature sender.
• If engine coolant temperature gauge still tests out of calibration, replace coolant temperature gauge.

Oil Pressure Sender

Check gauge operation as follows:

• With the key in RUN and the engine off, disconnect wiring connector at the switch. The gauge should indicate on the LOW graduation or below.
• Connect the wiring connector to the engine block ground. The gauge should indicate just slightly above mid-scale.
• If the oil pressure gauge tests within calibration, replace oil pressure switch.
• If the gauge still tests out of calibration, replace oil pressure gauge.

Battery Voltage Gauge

Test the battery voltage gauge as follows:

• Turn the key to RUN, turn the headlamps on, and set the heater blower/fan on high with the engine (6007) stopped. The gauge pointer should move toward the lower portion of the normal band (the white marked area).
• If no movement of needle is observed, check the fuse and the battery-to-circuit breaker and circuit breaker-to-cluster wire connections.
• If connections are tight and wire continuity is good, remove the instrument cluster (10849) from the vehicle.
• Check for flex circuit continuity and confirm flex circuit-to-clip and clip-to-gauge contact.
• If all connections are good, replace the instrument cluster.

Charge Indicator Lamp System

Normal Charge Indicator

With key off, charge indicator (battery symbol) lamp is off.

With key in RUN (engine (6007) not running), charge indicator (battery symbol) lamp is on.

With key in RUN (engine running), charge indicator (battery symbol) lamp is off.

1. If the charge indicator lamp does not light with the key in the RUN position (engine not running), check the I wiring circuit (ignition switch to regulator I terminal), for an open circuit or burned out charge indicator lamp.

2. If the charge indicator lamp does not light, disconnect the wiring plug connector at the regulator and connect a jumper wire from the I terminal of the regulator wiring plug to the negative battery post cable clamp.

3. The charge indicator lamp should light when the key is turned to RUN (engine not running).

4. If the charge indicator bulb does not light, check the bulb for continuity and replace if necessary.

5. If the bulb is not burned out, an open circuit exists between the ignition switch (11572) and the voltage regulator.

6. Check the 500-ohm resistor across the charge indicator lamp.

For additional diagnosis and testing procedures, refer to Section 14-00.