2008 F150 Dead Electrical Systems
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10-09-2013, 02:48 PM
Join Date: Oct 2013
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2008 F150 Dead Electrical Systems
Hi Folks.
I'm new here after scrounging the Internet looking for help with my neighbors 2008 F150 no start and Electrical problem. She brought (actually towed) the truck to me hoping I could help (being an Electronics Major and working 35 years w ATT/NASA/etc and now operate own electronics shop) anyway she had taken the truck to a fellow for a no start problem. It would crank and supposedly had power to systems but wouldn't start. The fellow changed out the Battery, battery cables, starter and fuel pump and now it won't even crank over and many electrical system are dead. He advised her to take it to dealer since he couldn't make it run but charged her a lot of $$$$.
After making her get me the 2nd original key since she had painted the first with Pink and Gold metal-flake paint ( don't paint Smart Keys!!!) I started checking things and found he had broken the starter selonoid during installation and even left out the top mounting bolt. She had bought a lifetime warranty on the starter so took it back, got another and installed it correctly. Also rewired the battery cables correctly (you don't use wirenuts and duct tape on battery cables or leave them laying on exhaust manifold)
The engine still won't even turn over. Broke out my meters and test leads and started checking things only having the owners manual to go by (that's why I'm here looking for wiring diagrams or real help, I don't want magazines, movies, games or any other bogus Internet junk thanks) ).
Going by Owners manual all the fuses are good, correct sizes and location for each circuit. I pulled each relay and tested them, all ok and contacts operate good with no intermittant operation.
With the key in the ignition and the run position almost nothing on the truck works except horn, headlights (they will light even without key in run, no running or stop lights though), no interior lights, no annoying bells or buzzers going off, only the Airbag light on the dash is lit but seems to go on and off. The red light on top of the dash is blinking a lot. The dash fan does operate though. The fuel pump isn't running either. She had the old pump so I checked it and found no problem, it runs ok with 12V on pump. I checked new pump after lifting bed up (they sure make these beds lightweight nowdays) and it also runs with 12V on pump pins on 4 pin connector (fellow even broke connector latch tab so had to tie-wrap it back together)
I checked the connector for the starter selonoid next to the engine and when the key is turned to run and/or start there is no 12V from the relay/fuse panel. Same with the fuel pump. Also the console shifter does not unlock with the key in run and brake pedal depressed. I found a partial starter diagram on another post here but it's for a different year and doesn't match this truck but there is 12V on the ignition switch.
What system or module would cause all these systems to be dead when there's 12V on fuses and relays? These wiring harness's run all over the place on this truck and I'm stuck without schematics. The local Auto parts manuals don't have real wiring diagrams, just some vague pictures and nearest Ford dealer is 45 miles away and want's an arm and leg for manual. Can anyone help?
From Texas Gulf Coast hoping you can help
Thanks
I'm new here after scrounging the Internet looking for help with my neighbors 2008 F150 no start and Electrical problem. She brought (actually towed) the truck to me hoping I could help (being an Electronics Major and working 35 years w ATT/NASA/etc and now operate own electronics shop) anyway she had taken the truck to a fellow for a no start problem. It would crank and supposedly had power to systems but wouldn't start. The fellow changed out the Battery, battery cables, starter and fuel pump and now it won't even crank over and many electrical system are dead. He advised her to take it to dealer since he couldn't make it run but charged her a lot of $$$$.
After making her get me the 2nd original key since she had painted the first with Pink and Gold metal-flake paint ( don't paint Smart Keys!!!) I started checking things and found he had broken the starter selonoid during installation and even left out the top mounting bolt. She had bought a lifetime warranty on the starter so took it back, got another and installed it correctly. Also rewired the battery cables correctly (you don't use wirenuts and duct tape on battery cables or leave them laying on exhaust manifold)
The engine still won't even turn over. Broke out my meters and test leads and started checking things only having the owners manual to go by (that's why I'm here looking for wiring diagrams or real help, I don't want magazines, movies, games or any other bogus Internet junk thanks) ).
Going by Owners manual all the fuses are good, correct sizes and location for each circuit. I pulled each relay and tested them, all ok and contacts operate good with no intermittant operation.
With the key in the ignition and the run position almost nothing on the truck works except horn, headlights (they will light even without key in run, no running or stop lights though), no interior lights, no annoying bells or buzzers going off, only the Airbag light on the dash is lit but seems to go on and off. The red light on top of the dash is blinking a lot. The dash fan does operate though. The fuel pump isn't running either. She had the old pump so I checked it and found no problem, it runs ok with 12V on pump. I checked new pump after lifting bed up (they sure make these beds lightweight nowdays) and it also runs with 12V on pump pins on 4 pin connector (fellow even broke connector latch tab so had to tie-wrap it back together)
I checked the connector for the starter selonoid next to the engine and when the key is turned to run and/or start there is no 12V from the relay/fuse panel. Same with the fuel pump. Also the console shifter does not unlock with the key in run and brake pedal depressed. I found a partial starter diagram on another post here but it's for a different year and doesn't match this truck but there is 12V on the ignition switch.
What system or module would cause all these systems to be dead when there's 12V on fuses and relays? These wiring harness's run all over the place on this truck and I'm stuck without schematics. The local Auto parts manuals don't have real wiring diagrams, just some vague pictures and nearest Ford dealer is 45 miles away and want's an arm and leg for manual. Can anyone help?
From Texas Gulf Coast hoping you can help
Thanks
#2
10-10-2013, 10:20 AM
#3
10-17-2013, 12:24 AM
Senior Member