My Truck:
1999 Ford F-150 Extended Cab 4x4 5.4L V8

So the other day I was driving the truck and it just dies on me. Tried starting but it just cranked and cranked. Got it pulled over to a parking lot and then tried to start and I got it to run again. Died a couple mins later uo the road and it will not start at all anymore. I got it towed to my driveway and I've started diagnosing some things.

I dropped the tank thinking it was a pump I replaced awhile back. The pump wasn't running but jumped to conclusions and took it back to the auto parts store. They bench tested and it works fine. I checked for voltage at the pump connector. NOTHING. So I'm not getting power to Fuel pump. Then I checked the fuse and relay for the fuel pump. Everything was okay.

I did some research and decided to check for spark. NO SPARK. Another thing I noticed the other day was that the odometer is displaying all dashes. So I'm really unsure on what to really troubleshoot. I am going back to the truck tomorrow to check a few other things. I'm not sure if the Theft light is blinking or not so I will check that tomorrow and get back to you.

While searching the forums there is just so much that could be messing this up and I'm just confused on what path to take to start narrowing it down.

Any suggestions on what to check tomorrow? Any other relays or fuses besides the fuel pump? What about any modules to check like PCM, GEM, etc. Or I've heard the crankshaft sensor could be an issue. Please help. I appreciate your time. THANKS!

 

My 2003 wouldnt start one night, would just crank and crank. Theft light was going nuts... I cant remember if i had all dashes in the odometer but I think I did.

Try changing out the relay for the ECM. You can swap it with the trailer tow battery charge relay, or it might even still be with the trailer harness that came in the glovebox. That was my problem, Bad relay would not power up the ECM or PCM or whatever they call it.

 

So here's a quick update. Decided to go over there tonight and do a little more troubleshooting. I played musical chairs with the relay and still had no luck. I didn't try a relay from the inside as they are the same as well so I might do that tomorrow.

I did run a diag through the instrument cluster and it displayed the following codes:

9681 PATS Tranceiver Signal is Not Received (Not Connected, Damaged, or Wiring)
d147 SCP (J1850) Invalid or Missing Data for Vehicle Security PCM REFER to Section 419-01.
Missing SCP Message J1850 REFER to Section 418-00

So could the PCM not getting power be causing the errors with the PATS system or do you guys think it could be the PATS transceiver itself failing? Is there a way to test either? Maybe it still is a relay and I could jumper the relay points even though I dislike doing that.

 

The PCM not getting power would cause all 3 of those codes for me. I'd be willing to bet that if you hooked it up to a regular scanner that it'd throw at least another dozen codes at you just like mine did.

My PCM relay was in the fuse box under the hood, and was a large square one. You might check all your wiring harnesses and make sure you didnt have one come loose as well.

 

Okay I will definitely look into further today. Thanks for the info. I also forgot to add that the Theft light is blinking rapidly. so I will definitely check into the Relay and plug in a scanner. I will also check for any messed up harnesses.

 

Try your spare key also.

 

........I'll 2nd what Steve said...try another key..that rapid blinkning theft light is the PATS system not authorizing the truck to start

 

Tried the PCM relay and it's working properly even switched it with a working one to make sure. No joy. The relay itself is getting power but the switched power to go to the PCM when the relay is active is not there. I will have to go grab my spare key from the place I'm making payments to. I'm really feeling like the place I bought it from has jipped me with the condition of this car. I'll get back to you after trying the spare. Thanks again!

 

I'd be checking all fuses related to the PCM, etc at that point if you dont have the power at the relay... Based on your first first, theres a possibility that you had a weak (ie cracked) fuse that would let it work periodically, but has since given up. I pulled up your owners manual online and it appears that there are at least a half dozen fuses you'd need to check...

 

If the PCM isn't getting power, there are usually only two fuses that need to be checked: CJB F30 & F24.

 

So the relay and fuses checked good. I'm really stumped right now. I just even said to hell with it and checked ALL relays and the fuses. None were blown except for a maxi fuse for the tow/trailer lights? Only fuses I haven't found were the mega fuses.

 

Is there anywhere you have a loss of power such as lights?
What shows on the dash in the 'run' position before cranking?
Dash checkout lights and Theft lamp action?
Do you hear the fuel pump for a few second when turning to the Run position?
If yes, the PCM is getting power because the pump relay gets it's ground from the PCM. Your key to Run powers the PCM to do that.
Depending on what the situation is, you can check for fuel pump action by checking the fuel pressure at the port using mutiple 'key on' cycles.
I'm trying to get my picture to possibly help you out finding a direction to go..
Good luck.

 

Thanks for all your guy's help again. So No fuel pressure. No spark. All interior power is there though. Lights, cigarette lighter port, headlights and all work. The Instrument Panel lags. Fuel level and everything won't display until I leave it in the on position for about 30-45 seconds. The Theft light blinks rapidly indicating it's in theft mode.

 

..Once again..did you try another key?? The Pats system is not seeing the correct coded key, hence, giving you the rapidly flashing theft light

 

Do this and see what the result is.
Turn on the ignition to RUN.
Let it set that way for a few minutes.
If the Theft light begins to blink a two digit code,
be sure you count the flashes the same a couple of times and post what you saw.
Hopefully, there is a code that will tell me what the major issue is, then you will have someting to run with.
Good luck.