Major electrical gremlins lurking
 

Gentlemen,

Newbie here. I purchased a 2003 4.6is about 7 months ago and it ran perfectly until 2 weeks ago. I am in need of help and hoping someone can help me solve my electrical gremlins. Here is a list of what happens once the car is started and travels about 5 miles: ( Also it never used to have these symptoms. Only in the last 2 weeks have the gremlins surfaced.)

1) trans fail safe mode illuminates
2) While driving the PRN"D" light will disappear sending it into Trans Fail Safe mode
2) self level susp inactive illuminates
3) When I use the key fob to open the door, the alarm goes off instantly with the push of the unlock button.
4) While driving, the a/c will will blow cold air and for some reason keep blowing but no more cold air.
5) the steering will feel great one minute and then become noticeably harder to steer
6) The needle on the temperature gauge jumps into the red immediately.
7) The needle for transmission temperature gauge jumps to hot.
8) We have had rain rain and more rain here in South Florida and behind the drivers seat the floor is wet.
9) 30amp Fuse for the self leveling suspension in the boot/trunk blows every time I replace it. ( the last fuse in the sequence of fuses). The 7.5amp fuse remains intact.

I purchased a new battery recently and just today put in another battery just to test and see if it was in fact a dead battery. The car displays the same symptoms. I have recently also changed the water cooled alternator 4 months ago. And yes the car does shut down and goes to sleep after 16 minutes..... Where could I possibly have a short in the system??? The rear trunk is dry as a desert. Also the radio works.

Thanks for taking the time to read. any suggestions will be greatly appreciated.

Sounds like a wiring harness damaged somewhere.

With the prndl light acting up I would first remove and clean the transmission connector under the car but you need to trace a number of wire harness and look for some damage like rodent chewed on etc.

If you feel it is directly related to all the rain, I would start with finding the source of water getting in. Often it is the sunroof drains plugged that allows water to get into the interior though I don't recall that causing the myriad of symptoms you are experiencing. I assume by rear bone drive means you checked the spare tire area. Since the self leveling fuse blows immediately that seems a good starting point for troubleshooting. Some of your symptoms sound like a bad ignition switch but you didn't mention anything about and starting issues. Did you drive through standing water?

(of course) it's most likely that a single problem is causing all the symptoms on that list - nice work on the detailed list.

Most of the things on that list seem like they could be explained by an electrical issue, except ...

#5 - steering. I don't have detailed knowledge of the systems in these E53s, but I don't know if that could be caused electrically. It definitely could be caused by a problem with the drive belt failing to drive the power steering pump ...

as could #6 - coolant temp suddenly rising (if the drive belt is failing to drive the water pump) and ...

#7 - ATF temp rising (since the coolant temp is high, heating the ATF via the ATF cooler)

So I'd consider a belt issue in addition to the other things. Since the problem is intermittent, maybe it's an issue with the tensioner (one of these for each belt).

But given item #4,

#4 - AC not blowing cold - at least on the M54 (sorry, different, but maybe similar on yours) the AC has its own separate belt.

on a separate belt, and if we're still assuming that only one thing failed, maybe look at the crank pulley / harmonic balancer. Those are actually two-piece designs, with a rubber connector to provide damping. The rubber can fail, leading to separation. If you can reach the crank pulley (will have two belts on it - one for AC, one for everything else), push or pry on it with something. It should feel completely solid. If it moves at all, that's a problem.

Similarly, if both belts get wet, they could both start slipping, causing the same problems. So similarly, looking very closely into the belts getting wet (BTW - can simulate that by simply spraying them with a hose) would be something to consider. Are you missing splash panels?

One question - it seems implied in your question, but not clear - do sometimes ALL of these problems go away completely, before ALL coming back at about the same time?

Thanks all for chiming in. I will check the wire harness and pull the transmission connector to see if any water is in there. The belts were all new as I replaced the when I replaced the water cooled alternator as well as the belt tensioner. The belts are all nice and tight. And it doesnt overheat at all. The needles just decides to move to that location. However I will recheck the power steering pump, alternator and the water pump again. Also my earth ground from the battery is clean and tight.

Electrical servo-assist steering rack.... :dunno: