Hi Guys. I'm having a problem with my 2002 F-150 that I can't figure out. I hope one of you have had something similar.

Jumped into the truck tonight and turned on the key. The dash lights came on and everything was normal for a second or two. After that, it seemed that all power failed. I had a couple dash lights left on, but they slowly dimmed out. The battery saver relay in the interior fuse panel clicked a few times and then went silent.

After the electrical failure, I cleaned the battery terminals and checked that the battery was charged. By the time I got all that finished, whatever relay failed had reset. I put the key back in the ignition, turned it and had the same result as before. Everthing was fine for a second or two and then the power failed. A few clicks of the battery saver relay and then nothing.

Anyone seen this before?

Thanks for your help.

 

Might need to replace the battery. Take it out and have it checked.

 

Agreed, have the battery checked. Check the voltage at rest and then turn the key and test it after things fade away. Each cell should produce 2.1 volts. So an ideal voltage would be 12.6. Anything between 12.4 to 12.8 is OK. I suspect that your voltage will be considerably less. Anything below 10.5 and the battery is fully discharged. While you are having the battery checked have the alternator checked too. Jumping the battery may have damaged it.

 

Agreed, have the battery checked. Check the voltage at rest and then turn the key and test it after things fade away. Each cell should produce 2.1 volts. So an ideal voltage would be 12.6. Anything between 12.4 to 12.8 is OK. I suspect that your voltage will be considerably less. Anything below 10.5 and the battery is fully discharged. While you are having the battery checked have the alternator checked too. Jumping the battery may have damaged it.

 

Thanks for your help. I'll check out the battery tonight after work.