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AMEDEE
AMEDEE, FORD TECHNICIAN
Category: Ford
Satisfied Customers: 24399
Experience:  ASE CERTIFIED TECHNICIAN ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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I was repairing the wiring to the factory installed trailer

Customer Question

I was repairing the wiring to the factory installed trailer plug now the truck won't start fuses and relays are all good any ideas
Submitted: 8 months ago.
Category: Ford
Expert:  AMEDEE replied 8 months ago.

Hello and welcome! My name is ***** ***** I can assist you with your question. What size engine do you have? Does the engine crank over but not start or does it not crank over at all?

Customer: replied 8 months ago.
4.6 liter turns over very well new starter new battery within last year
Expert:  AMEDEE replied 8 months ago.

Ok, does the engine have spark when cranking? Does it run on starting fluid?

Customer: replied 8 months ago.
Haven't tried to check for spark or use start fluid
Expert:  AMEDEE replied 8 months ago.

Does the check engine light come on with the key on and does it go off while cranking?

Customer: replied 8 months ago.
No check engine light when cranking
Expert:  AMEDEE replied 8 months ago.

Ok this is the problem. The computer is not awake and therefore the engine will not start and run.

Expert:  AMEDEE replied 8 months ago.

The next step is to check all powers and grounds going into the computer. This includes all powers from all fuses, fusible links and even the ignition switch.

Customer: replied 8 months ago.
Ok where do they hide that computer
Expert:  AMEDEE replied 8 months ago.

The computer is under the hood right side of engine compartment

Customer: replied 8 months ago.
Behind the battery? does the battery box need to be removed
Expert:  AMEDEE replied 8 months ago.

One minute while I get you a pic

Expert:  AMEDEE replied 8 months ago.

It is number 52 in the pic

Customer: replied 8 months ago.
The pins and the connector all look good shinny no corrosion
Expert:  AMEDEE replied 8 months ago.

Right.. but that does not mean it has power going to it.

Customer: replied 8 months ago.
Just looking next to the power distribution box is another box full of relays can you tell me what they're for
Expert:  AMEDEE replied 8 months ago.

They are for a lot of various other components on the vehicle. However, relays usually do not prevent the engine from starting.

Customer: replied 8 months ago.
Okay I want to back up a little bit here I double-checked the 5 amp mini fuse under the dash with my test light I'm not getting any power on other side of the fuse and the fuse is good
Customer: replied 8 months ago.
If I understand you correctly when the ECM has power the check engine light should be on with the ignition switch turned in the on position
Expert:  AMEDEE replied 8 months ago.

YES, that is correct.

Customer: replied 8 months ago.
Ok did you read my question before the check engine light about no power at the 5 p mini fuse
Expert:  AMEDEE replied 8 months ago.

YES, I did. Which fuse does not have power? Keep in mind, sone of them will not have power and this is ok.

Customer: replied 8 months ago.
Sorry it's position #20 in the fuse panel under the dash in the owners manual fits identified as powertrain control module generic Electronic Module Central timer module
Expert:  AMEDEE replied 8 months ago.

Do you have an auto or a manual transmission?

Customer: replied 8 months ago.
Auto trans
Customer: replied 8 months ago.
2FTZX18W1WCA60470 IS THE VIN
Expert:  AMEDEE replied 8 months ago.

According to my wiring diagram, that circuit is only for a vehicle with manual trans

Expert:  AMEDEE replied 8 months ago.

Here is how to diagnose this condition.

Check for battery voltage on the solid Red wire that goes to the Idle Air Control valve. This is the same wire that powers up the PCM at pins 71 and 97 from the PCM power relay and feeds power to the primary side of the fuel pump relay. If no voltage is present, check for a blown fuse. Fuse 24 in the Battery Junction Box is a 30 amp fuse that should be hot at all times and feeds the secondary side of the PCM power relay. Fuse 30 is in the Central Junction Box (CJB) and is a 30 amp fuse that should be hot when the key is in the run position and feeds the primary side of the PCM power relay. Also check fuse 18, 15 amp fuse which is between the PCM power relay and the injectors.

Customer: replied 8 months ago.
Ok so does it run a common ground or does it on an insulated ground
Expert:  AMEDEE replied 8 months ago.

I am talking about the power circuits in my last post.. not grounds..

Customer: replied 8 months ago.
I understand I'm just trying to satisfy my own curiosity I am a licensed truck and Coach technician from the province of Ontario I've not had much to do with Ford's pick-up or cars for that matter
Expert:  AMEDEE replied 8 months ago.

Ok, no problem. However, I dont understand your question.

Expert:  AMEDEE replied 8 months ago.

Sure it could be a bad ground, but we need to check them (and the powers) directly at the PCM with the key on. Please do this and let me know what you find. Going to get some sleep. Talk to you in the morning!

Customer: replied 8 months ago.
Ok what time zone are you in I'm in mountain time
Expert:  AMEDEE replied 8 months ago.

I'm in eastern time zone

Customer: replied 8 months ago.
Good morning.....well I have no explanation I quit troubleshooting my electrical problems last night and went back at it this morning 1st thing I turned the ignition to the on position low and behold the check engine light illuminated so I turned the ignition to the crank position and the started and ran like nothing happened
Expert:  AMEDEE replied 8 months ago.

Hello! That is great news that the engine has started right up this morning! Lets hope it continues to start and run. If not, at least you now know what to test/check for when this condition occurs. Electrical components can and will do this when they start going bad. I see this all of the time working in this field. Intermittant issues are a mechanics worst nightmare

Customer: replied 8 months ago.
I agree back in the late 70s early 80s when electronic ignition first came out you had to carry a spare ignition module in your glove compartment for the Fords because they would just fry for no reason at all you obviously have a great deal of experience with these pickups do you think I might need to replace the PCM on this thing
Expert:  AMEDEE replied 8 months ago.

The PCM is a possible cause and they do bad bad. However, this is the last thing that should be replaced for this problem. Everything else needs to be checked and ruled out before the PCM gets replaced.

Expert:  AMEDEE replied 8 months ago.

I am glad I can help!

It has been a pleasure working with you. Please dont forget to honor your good faith deposit by rating my answer as "Excellent Service" for assisting you today.

Please let me know if you have any further questions.

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