1996 K1500 4.3 V6 No power to instrument cluster, Engine cranks, fuel pump cycles but no spark. Physically pulled every fuse (all good) checked the fuse relay center under the hood all fuses good but.. The ECM-1 and the ENG-1 both read under 1 volt with the ignition on. Does this mean the ECM is shot or is the ignition switch??

Take it to a qualified repair shop an have a full vehicle scan done . Do you know what that is ? Hooking up a factory or professional scan tool an checking for code's in all the modules on the vehicle , instrument cluster , SJB - smart junction box - ford's BCM , What do you mean it remains on empty ? What have you done ? Did you replace the fuel level sending unit in the tank ? Replace instrument cluster ?
Instrument Cluster Diagnostic Trouble Code (DTC) Index DTC Description Source Action B1202 Fuel Sender Circuit Open Instrument Cluster Go To Pinpoint Test B . B1204 Fuel Sender Circuit Short to Ground Instrument Cluster Go To Pinpoint Test B .
Instrument Cluster Self-Test Mode
To enter the instrument cluster self-test mode with the engine off, press and hold the odometer reset button (base cluster) or simultaneously press and hold the message center reset and setup buttons (message center cluster). Turn the ignition switch to the RUN position and hold until the display indicates tESt (base cluster) or TEST (message center cluster) usually within 3 to 5 seconds. Press the reset button once to advance to each stage of the self-test.
To exit the instrument cluster self-test mode, turn the ignition to the OFF position. If no DTCs related to the concern are retrieved, GO to Symptom Chart .

• Incorrect fuel gauge indication

• Circuitry
• Fuel pump module
• Fuel tank
• Instrument cluster

• Go To Pinpoint Test B .

Hi, have you checked or replaced the oxygen sensors?

You have no idea what your messing with . Theft light on , DTC'S - diagnostic trouble codes stored . Before you start replacing BCM an making matters worse ,do yourself a favor an take it to a qualified repair shop .
The powertrain control module (PCM) communicates with the instrument cluster using serial data over the UART serial data bus, CKT 800. When the instrument cluster determines a Pass Theft condition, the instrument cluster sends a coded password to the PCM. When the instrument cluster receives the correct password, the PCM enables the fuel injection system in order to allow the vehicle to operate normally. The PCM may allow the vehicle to start and stall quickly during a failed theft condition.

The Passlock™ lock cylinder is a locking cylinder that turns a rotating magnet past a stationary hall effect sensor. The rotating magnet creates a resistance code (R-Code) that the cylinder sends to the instrument cluster. The Passlock™ lock cylinder interfaces with the instrument cluster through a 3 wire connection. The 3 wires have the following functions:
• Power
• Ground
• Data
The THEFT SYSTEM indicator will not light under any circumstances.
Replace the instrument cluster.
For Chevrolet vehicles, refer to Instrument Cluster Replacement .
For Pontiac vehicles, refer to Instrument Cluster Replacement .
Multiple indicators light continuously.
Test for a loss of serial data. Refer to Data Link Communications System Check .
Instrument cluster DTC B1021 sets.
The DTC indicates a loss of powertrain control module (PCM) serial data. Refer to Data Link Communications System Check .
Instrument cluster DTC B1022 sets.
The DTC indicates a loss of SIR serial data. Refer to Data Link Communications System Check .
Instrument cluster DTC B1023 sets.
The DTC indicates a loss of ABS serial data. Refer to Data Link Communications System Check .
Instrument cluster DTC B1011 sets.
Refer to DTC B1011 Passlock Cyl Data Shorted This Ign Cycle in Instrument Panel, Gauges and Console.
Instrument cluster DTC B1012 sets.
Refer to DTC B1012 Passlock Bad R-code This Ignition Cycle in Instrument Panel, Gauges and Console.
Instrument cluster DTC B1013 sets.
Refer to DTC B1013 Passlock Bad Timing This Ignition Cycle in Instrument Panel, Gauges and Console.
Instrument cluster DTC B1014 sets.
Refer to DTC B1014 Passlock R-code Unprogrammed in Instrument Panel, Gauges and Console.
Instrument cluster DTC B1015 sets.
Refer to DTC B1015 Passlock Cluster Fail Enabled in Instrument Panel, Gauges and Console.
Instrument cluster DTC B1017 sets.
Refer to DTC B1017 Passlock R-code Learn Failed in Instrument Panel, Gauges and Console.
The indicator flashes and no instrument cluster codes are set.
Refer to DTC B1013 Passlock Bad Timing This Ignition Cycle in Instrument Panel, Gauges and Console.
So , do yourself a favor an have a qualified repair shop check it out .

Any lights lit or flashing on the instrument cluster when cranking the engine . SECURITY car an padlock symbol ? Some anti-theft system will stop injectors from squirting fuel if there is a problem . No lights check fuel pressure , go to you tube an check out videos on how to do it . Ford , Lincoln , mercury use a fuel inertia cut off switch ,cuts Battery power to fuel pump . All so your vehicle may have a FPDM - fuel pump driver module , the engine computer sends signals to the FPDM to tell it how fast to make fuel pump spin .Given the complexity of your vehicle an the special tools to diagnose it , I strongly suggest you take it to the dealer or a ASE certified repair shop . That's just my professional opinion .

Only the 1MZ V6 has this relay. On the 4-cyl, the fuel pump runs off the circuit opening relay, which is in relay block 6, behind the instrument cluster.

There is a disconnect for the fuel line in the engine compartment. Disconnect it at the motor and cycle the key. This will determine if your fuel pump is running. If it is not which I would assume it isnt then check the relay. If the relay is not clicking when you cycle the key then replace it. If you have low pressure then try replacing the fuel filter. This could cause low pressure and keep the vehicle from starting. If it is not fuel delivery then there is a problem with your timing or firing order.

NEED SOME MORE INFO... FIRST WHEN YOU TURN KEY TO THE RUN POSITION DOES THE CHECK ENGINE LIGHT LIGHT ON THE INSTRUMENT CLUSTER.. IF SO YOU KNOW YOUR COMPUTER IS POWERING UP... SECOND NEED TO KNOW WHAT IS MISSING...1...SPARK....FUEL OR INJECTION.. PULL ONE PLUG WIRE OFF COIL PACK HAVE SOME ONE CRANK CAR DO YOU SEE SPARK JUMPING ON COIL... SECOND SINCE YOU VERIFIED FUEL SYSTEM.. NEXT IS TO PLUG ONE PLUG AND SEE IF IT IS WET WITH GAS OR DRY LET ME KNOW AND I WILL HELP FURTHER

you must make sure the engine is creating the appropriate compression remove a spark plug and install a compression tester disconnect all other spark plug wires so the motor does'nt start during testing and check to make sure the motor is creating at least 100 - 150 psi on all cylinders if so the mechanical health of the motor is in tact. if not you may have to replace a timing belt. If it is an interference type motor and the timing belt is indeed broken or jumped a tooth the valves may be bent and extensive engine repair will be needed

this could be a bad pressure regulator that is what sends the signal that kicks in your relay

Does the pump cycle eventually if you keep cycling the key off/on, without trying to start the car ?