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Ford p71 crown vic 2004 crown vic p71 wont start unless i

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2004 crown vic p71 wont...
2004 crown vic p71 wont start unless i turn the key on and off a hundred times untill the check engine light comes on, then i can drive it and acts normal untill i let it sit for 3hrs or so, then it does it again
i replaced the pcm because it fried the old one,
any ideas?
thanks
Submitted: 6 years ago.Category: Ford
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Answered in 13 minutes by:
9/16/2011
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
AMEDEE
AMEDEE, FORD TECHNICIAN
Category: Ford
Satisfied Customers: 27,079
Experience: ASE CERTIFIED TECHNICIAN ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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Hello!

If the check engine light is not coming on with the key on, this is going to be your problem. Your computer is not even awake! Chances are you are missing a power or a ground to the computer causing it not to wake up. The only other possibility would either be a bad computer or the computer is being shorted out by another computer or a sensor. I would start by checking all powers and grounds going to the PCM. THis includes all powers from all fuses, fusible links and even from the ignition switch.
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Customer reply replied 6 years ago
thanx amedee, ive got a bunch of power wires and grounds that are good going into pcm, is there anyway you could tell me which wires i need to be looking at? i cant find a good wiring diagram for this, is there one just for turning pcm on? a friend found me a diagram once,and we checked all the grounds and they were good
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
There should be two or three wires that power up the PCM. I can tell you the color wires or PCM pin numbers they should be going into if you need.

I would recommend to verify this by checking checking for 5 volts at the tps with the key on when the check engine light does not come on before you run this test.
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Customer reply replied 6 years ago
checked throttle position voltage, ive only got 0.05v
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Did you check all three wires at the TPS?

Was this with the key on?
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Customer reply replied 6 years ago
key was on ,tripple checked all three
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
These three pins should have power with the key on at the ECM

Pin 55

Pin 71

Pin 97
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Customer reply replied 6 years ago
cant find what pins are what, could you send me a picture, or a site i could look up?
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
I cannot copy and past diagrams as it is against copy write laws. but you can go to alldata.com and purchase a one time subscription for your vehicle that will have all of this information and more.
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Customer reply replied 6 years ago
figured that out, ive got no power to 71 and 97 but ive got power at 55
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Hello!

Try to power it up on pin 97 and 71 and see if the computer turns on..
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Customer reply replied 6 years ago
i got a check engine and battery light on now but no fuel cap light and fuel pump isnt pumping
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Does the TPS have 5 volts when you power these pins up?
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Customer reply replied 6 years ago
yep the brown and white wire
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Ok.. good!

So both pins 97 and 71 do not have power with the key on..correct?
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Customer reply replied 6 years ago
no, i put power to them to get 5v at tps double checked to see if i had the right wires 97 and 71 too
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Sorry for the confusion.. but there is no power to pins 97 and 71?
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Customer reply replied 6 years ago
there is now because i cut them and put power too them, was that bad? do i need to have power to the other ends of the wires i cut you think, dont meen to be dodgy, but i figured that would be ok, seeing they didnt work anyway
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
No.. that was ok.. just as long as you have the ability to repair them..

So even with this done the fuel pump does not come on with the key on and cranking?
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Customer reply replied 6 years ago
no , and the gas cap light doesnt come on either, if that helps
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Does it run on starting fluid?
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Customer reply replied 6 years ago

dont have any starting fluid but i do have a negative pulse at the coils and fuel injectors, so it should run

Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
NICE!

Does the fuel pump relay click when cranking it over?
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Customer reply replied 6 years ago
no, not at all, but something wierd, if i power those two wires up with key off the check gas cap light comes on, but not with the key on, fuel pump relay never kicks on though
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Ok.. turn the key on and check to see how many powers are going into the fuel pump relay..
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Customer reply replied 6 years ago
only 1 has power,
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
What color wire has power?
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Customer reply replied 6 years ago
a big green with an orange stripe
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
According to my wiring diagram, the fuel pump relay does not have a green/orange wire going to it?
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Customer reply replied 6 years ago

could be looking at the wrong one, but im looking at relay 203 and the dark green with orange stripe wire goes to fuse 5

Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Can you tell me the other color wires going to the fuel pump relay?
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Customer reply replied 6 years ago
orange/black red/black and black
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
That should be it! Only the other wire you did not mention should be light blue and orange. The light blue/orange wire and orange/black wire should both have power with the key on and cranking.
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Customer reply replied 6 years ago
dont have a light blue and orange wire in the whole box? orange/black wire dimmly glows my test light for a millisecond when i turn the key on but thats it, nothing while im cranking, just dark green/ orange has constant power with key on
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Is this a Vin W motor?
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Customer reply replied 6 years ago
the vin no. is 2fafp71wx4x179825 is that what you mean?
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
yes..

I just double checked two reliable serious and they both say the same thing..

There should be a light blue/orange wire going into battery junction box that powers up the other side of this fuel pump relay.
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Customer reply replied 6 years ago

ive got .. black o/black

 

red/black

green/orange

 

 

 

the green /orange wire goes to fuse 5, the rest go into loom, orange/black is shrinkwrapped together with two other orange/blacks that go to the other relays, one is the pcm relay

Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Yeah.. the green/orange wire that goes to fuse 5.. does this wire have FULL battery voltage on it?
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Customer reply replied 6 years ago
yep,
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Ok.. then the relay should click with the key on and when cranking..
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Customer reply replied 6 years ago
green orange is the only one that ever has power though, none besides that have power while cranking
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Yeah.. the other wire wire that is not getting power comes from the PCM power relay..

It sounds like the PCM power relay is not working or does not have power going to it. I would check that next..
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Customer reply replied 6 years ago
pcm power relay is clicking on and off with the key like its working now after i connected those two wires you told me, ill chek again though
Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
Check to be sure there is full battery voltage coming out of the orange/black wire when cranking the engine over.
AMEDEE
AMEDEE, FORD TECHNICIAN
Category: Ford
Satisfied Customers: 27,079
Experience: ASE CERTIFIED TECHNICIAN ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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AMEDEE and 87 other Ford Specialists are ready to help you
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Customer reply replied 6 years ago

wow, funny i got my buddy to turn it again, didnt work again for 4 trys, then presto, now its running

its still kinda acting wierd, but ill take it !!

thanx a lot mate!!

Ford Mechanic: AMEDEE, FORD TECHNICIAN replied 6 years ago
EXCELLENT!

Glad to hear it is up and running!

Have a great night!

AMEDEE
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AMEDEE
AMEDEE, FORD TECHNICIAN
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