Hello All,

Could someone give me a clue? I'm currently clueless after searching.

On the highway...going around 75mph, when I hit a bump the truck

Shifts to neutral and loses electrical power
Guages die
Radio dies

When going 35-45 and I hit a good bump the

Radio die
Guages die

Power loss I'm not sure yet if the engine is actually dying. I don't think so. I don't have to restart.

I did check a couple ground wires and reset computer by disconnecting battery.

Thanks,

bob

1999 F150
5.4L XLT Ext. Cab 2wd
199,800 ish miles

 

start off by checking your battery connections.

 

Done it, when I disconnected battery I cleaned connections too. I should have said that.

Thanks

 

Check the battery cable to starter motor solenoid relay switch on the firewall. Check the power from that switch to the Battery Junction Box in the engine compartment. Check the battery ground at the frame.

Regards

Jean Marc Chartier

 

had that same type problem on a old taurus..turned out it was just a loose main ground. drove me crazy for a week it would just suddenly die.

 

Thanks for the feedback guys...


I checked and cleaned the


Battery to solenoid connections

Battery terminals

Battery ground at the frame.

Visually checked the power from that switch to the Battery Junction Box in the engine compartment.


I'm gonna go for another test drive to get a better feel for what's going on. It takes a pretty good jar to make it happen.

Thanks,

bob

 

Just thought I'd add a picture to illustrate the check points made so far.

I'm still struggling to find this bugger...

 

ok so i'm going to assume your battery connections are tight and your grounds are tight. but are any of your ground straps ripped a little bit or are they close to other wires that could be touching them when you hit the bumps. and is your battery hold down tight and are the wires in your terminals tight. i just did a new terminal to a f150 4.6 because i could pull the positive wires right out of the terminal. those style terminals arent hard to break when they get some age on them. and is there any noise of shaking or anything going on under your hood. i'd go up to a speed bump and try driving over it and see whats going on if it does it a low speeds too.

 

Thank you Matts Ford.

The battery mounting is probably loose.

Strapping and wire I'll be checking tomorrow morning. (I'll climb in there and take a closer look I should say)

 

This post edited to prevent future user reference confusion. (the post was not related to the issue root cause)

 

...

 

i cant see what your trying to show too well. all i see is rust or something. but the whole problem still sounds like a loose or dirty ground connection somewhere to me.

 

Clarification edit. (Read on for root cause)

 

ok i re-read everything and you never mentioned if you checked the plug to the computer. check that for being loose or corroded terminals. i hate electrical problems. i'm out of ideas right now

 

check the ground wire on the engine block.
check the cab grounding points (outside the truck, from frame to cab)
and check inside the cab grounding points, both kick panel areas, will have to remove plastic trim to get to them.