HELP! Electrical problems (long)

[FarmFord]

I don't know where to go from here so I'm looking for serious technical suggestions. Vehicle is a 2005 Focus ST with about 99k miles.

Last Thursday night I was following a friend home who just bought a project truck to restore. I noticed my instrument lights appeared dimmer
than usual; I checked the dimmer switch to see if I had bumped it accidentally, but it proved to be at maximum illumination. So I kept going but remained alert.

My friend heard a knocking noise in the truck and indicated he needed to pull over. When we pulled to the shoulder of the highway, I shut off the Focus. When we tried to get moving again, it would not restart. The truck would also not restart, so we sat for about 40 mins trying to make troubleshoot both vehicles and come up with a plan for getting home. At the end of the 40 mins, the Focus restarted.

The instrument lights were still dim, so I left my friend behind and tried to make it to an exit. I suspected that the alternator or voltage regulator was failing, and I was running on the battery. I figured if I could make it to a shopping center, I could leave the car and come back for it the next day with my pickup truck and a car dolly.

I never made it to an exit. The Focus ran for another 13 miles, with auxiliaries cutting out one by one as the battery lost voltage. Eventually it lost engine power and was too dead to run even the 4 way flashers (hazard lamps). My friend rolled up with his classic pickup on a flatbed; the tow guy was able to tow another vehicle behind the flatbed, so the Focus went back to my friend's house with his truck.

Saturday morning I picked up a new alternator, battery, and serpentine belt and replaced them all. The old alternator was only putting out about 11V, so it was not charging properly; the new alternator, under full load with foglights, headlights, aux lights (pair of Hella FF75 behind the grille), HVAC, blower, stereo, etc was still maintaining 12.8V, so I considered that good. After I went out to dinner with his wife and my girlfriend, (took his car) the Focus would not start. I figured that the new battery may not have had a full charge from the auto parts store and jump started it to get it home.

On the way home Saturday night (a 40 min highay run) I went to flip the aux lights on and the car lost all electrical power. No lights, no ignition, nothing. I flipped the switch for the aux lights back to OFF and after a few seconds, the car came back on. Since I was still rolling and in 5th gear at about 50mph, the car roll started itself, so I did not need to use the starter motor. When I got home, I hooked a battery charger to the battery and left it on for 12 hours.

On Sunday I pulled the charger off; the indication said it had a full charge. Battery voltage at 13.1V. Focus still wouldn't start. I said to hell with it and drove my pickup all day Sunday and Monday.

Monday night I tried to start the Focus again, it would not start. I put a multimeter across the battery; Battery voltage at 12.8V with no load, engine off. While trying to start the engine I watched the meter; it never dropped below 12.3V. I don't think power was even getting to the starter motor. While trying to start it, the radio came on by itself several times, at 590AM, and also checking all slots in the CD changer (stock Audiophile headunit). I heard the solenoid click but no starter motor. Also, all gauges (temp, tach, speedo, fuel) fluttered at a high frequency between 0 and maybe 25% of their range. I heard the solenoid click, but no starter motor.

I disconnected the 12+V lead between the aux lights fuse box and the battery, isolating the hot side of all of my aftermarket wiring. No change, the car did the same bizarre things.

Not sure what to check from here. I need to get the Focus running again ASAP. Any sound technical suggestions would be greatly appreciated.

I DO NOT think it's starter, because that would not explain why the ignition cut out while driving after I replaced both the alternator and battery.

Regards,
Tony

[GapBoyPCS]

I'll move this to Team Tech for some more input.

[mikeeshaq]

OK get a cheap voltmeter. File the points of the test probes sharp like a needle. Stick one probe on end of the battery post NOT the battery clamp. The other end piece the insulation of the large cable going to the stater and make sure it contacts the copper in the cable. Crank the engine. You could also do this by turning on the headlights and piece the cable that would go to the fuse box. What you want to see is if there is any or rather how much voltage drop you get across those two points. My positive battery cable developed a bad connection right at the clamp. You could also do this on the negative battery post. I suppose you could even do this with a 12 volt light bulb (tail light type) in a socket in place of a voltmeter -highly subjective of course. If you do this this and you live up North where salt is spread on the roads, wherever you piece the cable be sure to place a spot of RTV over the cable to prevent salt laden moisture from getting in there. I do not know how much voltage is bad, I suppose you could try it out on a good car and see what a typical voltage drop is.