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2003 ford expedition power steering loss and dimming lights

Continuing the discussion from Advice on buying a 1999 Ford Expedition with 30k miles:

Hi, sorry to jack the tread. My 2003 ford expedition with the 4.6 v8 engine is having an issue i cant seem to pin point. The lights will get bright and then dim and the engine will die and i will lose power steering and brakes, it will start back up when i put it in park. Also while im driving randomly the rpms will shoot up to between 3 and 4,000 rpms and go back down. I have seen a video on youtube that says the fuse box in this model is very likely to short out and ruin the circuit board. Mainly looking for any experience any of you have with a issue like this. The check engine light is on, Showing two codes for running too lean and a code for Idle air controll valve. Mileage is 239,000 Thanks for any information you may share.

A bad or dirty IAC makes sense. I would replace it and it should fix your stalling and erratic idle. Then you can look at the lean condition.

A dirty IAC is likely to be the cause of the stalling at idle speeds, but if your RPMs are erratic while driving, I think that points to a gunked-up Mass Airflow Sensor (MAF) or possibly to a bad throttle position sensor (TPS).

Thank you for the reply. I will get a new iac and post back with results.

also the engine sounds like a jet engine (very loud and windy if that makes sense) in park or neutral but goes away when placed in drive or reverse.

This is your IAC valve. Start it and if it is idling high tap it with the handle of a screwdriver. If the idle drops to normal when you rap it the IAC is bad. Normally this is just carboned up and fouled, and you may be able to clean it up and reinstall it.

Because you have dimming lights and the power stearing is lost, you may want to check that the belt tensioner is keeping the serpentine belt tight.


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I would be amazed if my engine died and I did not lose power steering and brakes.

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You may have multiple problems there OP. For the above two symptoms, I suspect a vacuum leak of some kind. That can create a whistling or wind-like sound. And would usually throw a lean code too. Use a length of garden hose as a stethoscope to narrow down where it is coming from maybe.

Yeah i know that is common when your engine dies but it makes the problem alarming at highway speeds.

Yes. That could be exciting.