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Craziest Electrical problems 04 F-150V8 PLease Help!!!ATTEMPT 1
Hello all I appreciate each and everyone of you all! your my last hope!....bear with me, after I have described all the symptoms it will be rather long. My friend was driving his 04 ford f150 v8 towards a store close to him the f-150 with the truck just died and it wouldn't crank or start....so he called a tow truck and the tow truck driver recommended unplugging the throttle body assembly which is a "computer controlled throttle body pics below" after unplugging it, it did try and crank or rotate but never fired so it was towed back to his house.In the meantime he replaced the throttle body assembly and it did nothing he also replaced a sensor that attaches to the firewall I believe it was the evap solenoid (picture below) also replaced another component that had to do with the fuel system ill get the proper name of that component next time I talk with him. Nothing seemed to work but if you unplug the connector on the left going to the throttle body throttle motor its a 2 wire connector it will engage the starter and rotate it even fired up on starter fluid... he also put the stock throttle body back on when nothing had an affect on anything. He called me I am his friend and im also a mobile mechanic.. so when I arrived we tried the key and nothing happens no crank no starter, battery is full power. Again when we tried the key to prime the fuel pump I heard nothing and its not getting fuel at any time now too.. until the throttle body is unplugged from the right side (the two wire plug that goes to throttle body motor) it also likes to buzz when the key is turned to on position. When everything is plugged up to the throttle body it wont even engage the starter. How does the throttle body affect the starter? I checked the all fuses and relays they all look good.. when we tried the starter fluid and unplugging the right side of the throttle body it fired up and revved up due to the plate being partially propped open...this is strange to me something electrical is going on for sure.. also when the throttle body has both harnesses plugged into it the right and the left it will buzz and stop cranking the throttle plate doesnt respond to the gas pedal but it does return to idle position if manipulated manually. I plugged in the scan tool and only codes I've been getting are from the throttle body itself..is it a bad ground or shorted out wire. Also the gauge cluster dials will jump around at times and its definitely doing some crazy stuff electrically.. how does the throttle body 2 wire connector on the left have any affect on the starter engaging? no codes being thrown and all fuses and relays look good.. It even ran with starter fluid after I unplugged that 2 wire harness, He told me he put in a new throttle but it made no affect and he switched back whenever it did noting. everything else seems to work and it will run once it cranks on starter fluid with throttle body 2 wire harness is unplugged otherwise it does nothing at all no cranking or anything.. I didn't hear the fuel pump at any time so I thought it was that until he told me when it died it also didn't crank. So its electrical that seems connected to the throttle body somehow doesn't let it activate the starter??? what's going on I am totally perplexed. Here are some pictures below of the Throttle body with both connectors also the evap solenoid which shouldn't cause this?? please help I'm currently charging the battery tonight and doing some research online.. how can the throttle body cause the starter to stop unless unplugged on the left side (the 2 wire connector that goes to the motor for the throttle body) thanks for your help much appreciated. thanks again ATTEMPT 2
yes that does make sense because I cannot hear the fuel pump prime or any noises coming from the fuel tank area....the strange thing is that the truck wont crank the starter unless the throttle body's 2 wire harness on the left side is unplugged....so that is my first problem how could the throttle body stop the starter from turning the engine over. Only until the engine will turn over and allow the starter to spin will I be able to find why it isn't getting fuel. there's something going on with the throttle body to where it wont even try to start until its unplugged???? I would think that the starter would engage all the time but its dead when the throttle body is plugged in. this is the 2nd throttle body, same issue.
ATTEMPT 3
I tried to connect my screw driver to the one that's really low by the fuse block is connected to straight rust nothing happened, ill fix that today.... there's another on the drivers side ill check that too.... thanks i've got some more tests to do today and ill gather more pictures but how in the hell does the throttle body plug stop it from cranking lmao its killing the fuel pump and the starter until I unplug the left side throttle body 2 wire blk/rd connector then the starter will come back but not the fuel pump it did fire up with starting fluid after I unplugged the connector. i think he replaced the fuel pump driver module..
MORE INFO: oh yeah this is the 4.6 liter v8 not the 5.4 liter... im getting ready to gather some more info at the truck itself, swap some relays and check grounds thanks guys
ATTEMPT 4 yes I did alot more today but got nowhere,....charged up the battery all the way last night so we could make sure everything was properly energized, its still doing the same thing if that 2 wire harness is plugged in at all it kills any contact to the ecu my scan tools wont read or anything...tried swapping ecu relays with no luck.. so I tested the 2 wire harness that goes to the throttle body the red wire gets about 3.44 volts and the black wire when connected from ground to 12 volt source shows about 8.14 volts.. so I ran jumper wires to the red wire from the battery, then I grounded the black wire to the negative terminal on the battery. Once i did that then it would start to crank but not fire its not getting fuel no matter what I do. My buddy is checking fuel pressure at the fuel filter to see if the pump is pumping at all even when the ecu comes online when that harness is unplugged or given voltage and ground from the battery. If I plug it in to the throttle body it kills the ecu completely showing check gauges on the gauge cluster but when I unplugged the 2 wire harness it cranks but doesn't start.... I did get codes from the ecu that include some low voltage codes and codes for the throttle body itself. So we went ahead and got another throttle body and its still doing the same thing.. when plugged in that motor on the throttle body buzzes and it doesn't respond if you hit the gas pedal. We also checked the grounds coming from the fuse box which was basically grounded to rust before we re located the ground there and the drivers side ground at the kick panel is also okay and good looking.... Now if I can get the ecu to stay alive while the throttle body is plugged in.. I figure its still going to need to have the fuel pressure diagnosed because no matter what set up we tried it wouldn't start just crank and rotate ill look up some of the codes we pulled as well and share them with you...but nothing jumped out at me mostly throttle body codes because of it being unplugged there was a couple low voltage codes too... I tried erasing them and even giving that 2 wire harness 12 volts from the battery and grounded the black wire and it kept the ecu communicating and the check gauges display to disappeared but it still wont work even with a new throttle body installed which will be the second new one we have tried.... Im so perplexed lol please help ill try to get more data I have quite a bit of live data from my Launch crp909x scan tool which would only work if plug was unplugged or if that 2 wire harness was jumped otherwise I loose the ecu Completely...
Last and Latest attempt:
please anymore suggestions would help can anyone point me towards the ecu wiring pin out diagram or any wiring diagrams that would help... i need to follow all throttle body wires and test them from the ecu to the harness because its got to be that or the ecu itself??? please help me find some wiring diagrams that are eligible to download and clear enough to read, if you unplug the ecu harness connectors will the ecu need to be re programmed? IF i can get the wiring diagrams from the throttle body to ecu it might help significantly
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