The PCM doesn't supply power to the coil's ,it supply's a ground . A fuse supply's B+ power to the coil's . Your vehicle has what is called coil on plug ignition system , a coil for each cylinder . Should have plug wires ,has a spark plug boot . IT is common for these coil on plug system's to fry the driver (transistor) inside the PCM ,if the spark plug gap becomes so worn that the spark can not jump said gap. It shorts inside the coil sending high voltage to the PCM driver . There are video's on youtube showing how to test a PCM driver circuit . Your coil has two wires , one should have B+ voltage an the other goes to the PCM . If your coil fried i look for a short to ground on the control side circuit . This video is for a ford 5.4 l V-8 coil on plug system ,same thing just 2 more coils .
Ford 5 4 shorted coil primary winding and bad computer driver
First off you need to know how these thing's work , computer controlled . The SJB - smart junction box , a combination of fuse /relay & computer .
Do you know what DTC'S are ? SJB diagnostic trouble codes < not one's for the engine OBD 2 system . Need a factory or professional scanner to view these code's , Autozone , advance etc... can not read these code's .
Before replacing parts an taking the vehicle apart an checking wiring etc... Checking DTC'S should be the first step. So you know what diagnostic steps to use >
Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Index
DTC
Description
Source
Action
B1342
ECU Is Defective
SJB
CLEAR the DTCs. RETRIEVE the DTCs. If DTC B1342 is retrieved again, INSTALL a new SJB. REFER to Section 419-10 .
B1472
Headlamp (Low Beam) ON Switch/Circuit Short to Ground
SJB
Go To Pinpoint Test F .
B1510
Flash-to-Pass Switch/Circuit Short to Ground
SJB
Go To Pinpoint Test F .
B1570
Lamp Headlamp High Beam Circuit Short to Ground
SJB
Go To Pinpoint Test E .
B1797
Lamp Headlamp Low Beam Circuit Short to Ground
SJB
Go To Pinpoint Test D .
B2501
Headlamp, Left Low Beam Circuit Failure
SJB
If the low beam is inoperative, Go To Pinpoint Test D .
If the low beam is always on, Go To Pinpoint Test F .
B2503
Headlamp, Right Low Beam Circuit Failure
SJB
If the low beam is inoperative, Go To Pinpoint Test D .
If the low beam is always on, Go To Pinpoint Test F .
B2505
Headlamp, Left High Beam Circuit Failure
SJB
If the high beam is inoperative, Go To Pinpoint Test E .
If the high beam is always on, Go To Pinpoint Test F .
B2507
Headlamp, Right High Beam Circuit Failure
SJB
If the high beam is inoperative, Go To Pinpoint Test E .
If the high beam is always on, Go To Pinpoint Test F .
You would have no clue as to what you were doing without doing this first . Your best bet , take it to a qualified repair shop.
first the sensors on the exhaust manifold or before the cat converters are heated oxygen sensors ( not O2 sensors but HO2S sensors)
there are O2 sensors after each cat converter before any muffler
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I don't know what testing you have done? Make sure the battery has a full charge. If it cranks good but won't start, have a helper crank it while you check for spark at the plugs. If spark everywhere, use a gage and check proper fuel pressure. Also check fuel injector pulse.
How long since a tune-up? Any applicable trouble codes?
These codes are for coils 2 3 4 they are all bank 1 if you are standing in front of the vehicle looking at the motor bank 1 is the passenger side now disconnect the battery cables and then go to the connectors by the master cylinder unplug them and clean them also look for moisture inside the connectors they could be loose use alcohol and clean and let dry and also the other connectorside coming from the fire wall at the same location and inside the fender by the door you did not list what size engine you have but following what I'm telling you will cover all the bases here also check the connections to the computer making sure no pins are bent and no water inside also check the wire harness wires from those coils and for antifreeze or oil in those cylinders pull those spark plugs to inspect for fluids and for cracked insulators or cracked boots I know you said you changed the coils and was that complete with boots and are all new?I'm not there so I have to ask I'm really suspicious of fluid or water in those cylinders are your inner fender splash guards there did this happen after a heavy rain driving through puddles or the carwash? If so that's the problem those cylinders have water in them and it's shorting the firing + voltage to the - ground of the block please post back with more info and progress like I stated that I'm suspicious of this because it's 3 coils in a row the computer has separate pins for each coil if you have a 4.6 engine Vin code W I have an electrical diagram for a 2005 crown victoria 4.6 (W)they are the same but I don't think you need it check those 2/3/4 cylinders and plugs good luck stephen
I would check your "idle speed control" ISC on the intake manifold. It may just have to be cleaned. An ordinary can of carb cleaner should do the trick if the pintle valve inside is grunged up.
bad catalytic converter. The three coil's an spark plug's in the back ,under intake manifold . If the spark plug's on these coil on plug ignition systems don't get replaced the plug gap get's to wide an then the spark can not jump the gap . Shorts out the coil , find's shortest path to ground an it goes into the PCM an fries the computer . Your best bet , take it to a qualified repair shop
get the service and repair manual it will help you to locate and fix the problem by your own and you can get the manual from the given link http://toolsnyou.com/
Did you have the vehicle's control module system checked for DTC'S - diagnostic trouble code's ??????? Specifically the SJB - smart junction box , ford's BCM - body control module . Does the remote start/keyless entry still work ? Adding after maket system's to vehicle's (even your year ) isn't all ways a good ideal . It can cause major problems ! Having a qualified professional automotive technician check it out would be a good idea. Who installed these aftermarket systems ? Some of these place's have no idea what they are hooking to , any old place they can find B+ power .
Hello, is sounds like your issues are coming from within your turn signal/high-low beam switch. Most of the time the wires get worn or break and start rubbing around on each other causing troubles within the electrical circuit. Other times the contact switches inside the turn signal/high beam switch/lever wear and loose contact over time. You may be able to see wires leading from switch into steering colum. Check for bad wires, if none you may have to replace switch which you can get from any junkyard for bout 5 bucks plus learn how to take it apart in a junk car no one is worried about getting destroyed. BE CAREFULL WITH AIRBAGS when you pull your steering wheel to fix switch. It is not a difficult job to do.
