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Ford F150 FX4: 2004 Ford f150 5.4L wont crank with key. Will

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2004 Ford f150 5.4L wont crank with key. Will crank and run by jumping starter
Hello, My name isXXXXX for using Just Answer.

The most common cause for this is a faulty PCM Power Relay. Here are some diagnostic steps to narrow down the issue. You will need a voltmeter or a 12v test light. Please let me know if this is clear or if you need more information. Feel free to reply back with your findings or with any follow-up questions if you need to.

1. Check fuse #32 (15), #33 (15A), and #34 (20A) in the Central Junction Box (CJB) (interior fuse panel) with key on for full battery voltage. These fuses receive power from the Powertrain Control Module (PCM) power relay.

2. If none of the fuses have battery voltage as they should, check fuse #28 (5A) for battery voltage with key on. This fuse feeds the PCM power relay to turn it on with the key.

3. If fuse #28 is OK, remove the PCM power relay (relay #203) and verify that there are two terminals with full battery voltage with key on- one from fuse #28, the other should be battery voltage at all times and is hard wired to the battery voltage input to the CJB. If both terminals have battery voltage as they should, swap the PCM power relay with either the Trailer Tow Parking Lamp Relay (#201), or the Fog Lamp Relay (#202) and recheck operation. If fuses 32, 33, and 34 now have battery voltage, verify the vehicle starts and runs and replace the PCM power relay as needed.
Customer: replied 3 years ago.

32,33,34 have power both sides


Are you able to communicate with the PCM with a scan tool?

Is the theft light flashing with the key on?

Please let me know.
Customer: replied 3 years ago.

scan tool had no codes, checked a couple days ago. (Truck hasn't worked for two weeks)

security light flashes with key off. turn key on and it comes on for a couple seconds then turns off

It doesn't sound like the problem is with the PCM, PCM power relay, or the theft system. I suspect either a wiring issue or a partially blown fuse that may still be lighting the test light, but the currect path inside may be very weak.

I will go ahead and opt-out of the question to see if another expert has a more precise answer. Please hang tight for another expert to respond.
Customer: replied 3 years ago.



new expert here. Lets check for power to the range sensor at pin 10(DB/OG) and pin 12(TN/RD)

Power starts at fuse f2 102 in the CJB, goes to the ignition switch and then through the trans range sensor to energize the starter relay. The switch side of the relay gets power from fuse f2 101. check these fuses and the trans range sensor and let me know what you find

lets start here

good luck

Customer: replied 3 years ago.

I don't understand, where are the pins? in cjb. where is trans range sensor. I did try starting in neutral.

they identify the wire location in the connectors with pins(male and female terminals) . I gave you the wire colors that go with the pins we need to check. You can carefully back probe the connector and see as you try to start if power is going in and out where I told you to check. Multi meter is better that a test light. I use special probing adapters, you can use a paper clip

CJB is the fuse box inside the truck(central junction box)

The trans range sensor is on the side of the trans (drivers side)

it is under the shift lever and cable.

it was good that you tried to start in neutral



Customer: replied 3 years ago.

I unplugged trans range sensor to check pins, reconnected then turned to start and it cranked over. Must have been a poor connection in connector. Or do trans range sensors sometimes work after not?

You probably have a poor pin fit or corrosion. You can spray some electrical cleaner and then use some dielectric grease. Make sure there are no green pins/terminals. Sometimes water does get into these.

good job

Ironmike, Ford Technician
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Experience: 30 years ASE Master tech L1 . Ford master
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