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2008 F150 Electrical Gremlins


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  1. Hey Scotty I seem to be having what can only be considered as an electrical gremlin. I have a 2008 F-150 XLT 4x4 with the 5.4 liter 3 Valve Flex-fuel. I just recently purchased it and already took it to the shop where I sat around 5 hours twiddling by thumbs and they did nothing. The symptoms:

Brake light is on and won't turn off despite the parking brake being disengaged. Checked the brake fluid levels and they are fine, what's weird is randomly the light fixes itself but only temporarily while driving. 

The second ghost would be the TPS light is also on, the air seems to be ok in all the tires and when I tried the reset procedure the light went from steady to flashing for about 5 minutes then back on solid.

Thirdly the dome lights or map lights will on the rarest occasion come on all by themselves. I know they have been monkeyed with by the previous owner because they installed aftermarket idiot lights in the colors of blue and green on a red truck 🤣

Any thoughts? Ideally, since they are bringing me back in next week, I would like to say "hey this is what's wrong, fix it!" Instead of wasting another 5 hours. Now I know I am a retired veteran but I certainly have better things to do than sit around a shop with my thumb up my bum drinking free coffee.


Thanks in advance.

1 Answer

The TPMS light's probably on because the 13 year old batteries are dead in the readers in the tires. Those are expensive to replace and pretty much useless compared to the price to fix. Dig out the old manual tire pressure gauge once in a while. 

Check the brake switch on the parking brake. That may be broken or shorting out, causing the light to come on. My 1999 Ranger has the opposite problem and doesn't turn on that light when the parking brake is on, but it comes on with low fluid and such. I don't care enough about it to fix it. Haha.

The interior light wires might not be put together correctly. If the previous owners spliced things together, make sure it's all soldered and insulated. Shorts can cause them to turn on. Vibrating truck + a metal body + exposed wires = electrical shorts 


Thanks for the tips. Hoping since I just bought it and they said they would address the issue, the dealer will replace the TPS lights but we'll see 🙄. Was kinda hoping that it wasn't that and somehow all the gremlins were pointing at another issue, doesn't appear to be the case yet.