97 Taurus: New Alternator, New Battery, Now What?

electrical-wiring

#1

Ok, I have a 1997 Ford Taurus GL Wagon with about 99500 miles on it. The transmission was replaced in Aug, and a couple weeks after that was done, the battery light started flickering occasionally. It wouldn’t stay on, just flicker on and off, especially at night and/or at low RPM’s. The problem got worse (my headlights started fading, I could definitely tell the engine was not getting enough power) until a little over 2 weeks ago, the car just died. I got a jump, got it to a parts store to check the battery and alternator. They said the alternator was fine but the battery was bad. I replaced the battery. All seems well. The next week (I really only drive my car on the weekends) I have the same problem, the mysterious flickering battery light. So, I went to another parts store for another opinion, this new store said this new battery was fine, but the alternator doesn’t work (for the record, he used a tool similar to the light bulb tool, only it had several LED’s, some lit up if the battery worked, and others lit up if the alternator was working He just placed each end of the tool on the battery terminals and did the test with my car off and then my car started). My dad and I suspected this all along, so I just replaced the alternator. I drive off to the grocery store no problem, I can feel the engine getting power and struggling less, and now I’m thinking I have beat the my electrical woes.



Not so fast, I pull into the grocery store parking garage, and the car just dies while going up the ramp. No warning, no nothing, the lights go out, the engine shuts off and the car just stops and won’t start again, no lights come on, nothing. I rolled it down the ramp to get out of people’s way, and jiggled some wires, waited a couple minutes, and tried again, and the car started up fine. I drove it up the ramp, then drove it home with no problem.



I drive the car again this weekend, only this time, the car is just randomly shorting out. I was on the freeway, I heard a click and could feel the car start to stall as my headlights go out, but I revved the engine and everything came back on (well, except for the power steering, that didn’t come back til I restarted the car) This shorting out happened a couple times during the 35 mile trip, and each time I just revved so it wouldn’t stall. When I reached my destination, the turned the car off and tried to start it again, and nothing happened. So, I waited for an hour, came back out, and the car started fine. I drove it back home for another 35 miles, and the shorting was happening on the way home. Only this time, when I reached my destination turned the car off and tried to start it again, it worked no problem.



So I have a 2.5 week old battery and a week old alternator, and I’ve still got electrical problems. I’m going to take it back to the parts store to get it retested, but I’m thinking that the guy there might have misdiagnosed the problem in the first place…it seems like the tool would only catch if the charging system was working…so if the alternator is working but there is a bad connection, the test would show the same result as if the alternator were just bad. So I don’t trust this guy (or am I misinterpreting the wool he used) and want to know how I find if its just a bad connection?



Other possibilities I’ve been told are a bad fuse, or a bad serpentine belt. The belt seems fine, but it wasn’t replaced with the alternator again, because it seemed fine (no squeaking or disable cracks). I haven’t checked the fuse yet.



Ideas?


#2

Are the battery cable connections clean and tight at BOTH ends? It sounds to me like you have a bad connection, or possibly a bad cable.

It’s possible that when the transmission was replaced an electrical connection was not tightened completely. Start checking all the connections, including grounds, you can find.


#3

How exactly do I check the connections? Is there a tool, or am I looking for something in particular? What if the bad part of the wire is covered?


#4

It may be a grounding strap/wire was damaged when your transmission was done. The straps are usually a braided aluminum wire that is wide and thin. I don’t know where they are on your car but look all (above and underneath) around the transmission and engine compartment for one that may be poorly connected, partially cut or damaged, corrosion etc.

When you had the battery and alt preplaced I assume you double checked all the connections are clean and solid.

You need to get a load test on the electrical system performed to thoroughly test it. The Autozone I frequent has the equipment to do such a test and will do it for free. It is tested at idle and higher rpm’s. The hand held test light that your guy used is limitted. You can do the same with a volt meter.

You could spray some belt dressing on your serp belt to rule out belt slipping. It is unlikely from what you are saying and it only works for a short time but to be thourogh you may want do it to rule it out.

good Luck.


#5

The problem you are having isn’t due to a short, that would blow fuses out. As Mcparadise stated, you have a bad or intermittent power connection causing the trouble. The first thing to do is clean the battery connections, even if they ‘look ok’ using a battery post cleaning brush. That will eliminate this very common source of trouble. Next check is the power wire between the battery and the main power panel under the hood. Make sure power is getting to the main fuses when this trouble happens. There could also be a power relay causing the trouble or maybe the ignition switch. In order to find the trouble you will need at least a test light probe to verify power is getting to places it should be while the trouble is occuring. I would first identify key places in the power system to check for power when the trouble happens again so you will be ready for it the next time. Investing in a service manual would be a good investment to make.

From your statements it sounds like the battery and alternator were both bad or at least in marginal condition so replacing them was a good thing. There possibly could be something wrong inside the new alternator causing the trouble but I wouldn’t think that is the case unless other things have been eliminated first.


#6

You take them off (remove the battery end first) then inspect both ends and where they attach to make sure the metal is clean and everything is tight when re-connected. Be careful, crossing wires can give enough current to weld with (for a short time).

If there is a question about the wire itself, attach a OHM meter and twist and pull on the wire, it should read close to zero.