I'm having an intermittent starting/power issue on my 2000 Taurus and hoping someone may have seen something similar before.

Here's the background. The problem first showed up last June, my daughter went to start up the car and absolutely nothing happened, no crank, not even a click. I live in Arizona and have seen this before on other cars in the summer heat and it's usually a dead battery. Pulled the battery and took it in to be tested; it came up as noticeably depleted but still with more than enough cranking amps that it should easily turn the car over. We replaced it under warranty anyway, put the new battery in the car and it started right up. About a month later we had the exact same issue, pulled the battery again, thinking maybe we got a lemon, and had it tested. Battery tested out perfectly so we put it back in the car and it fired right up. Since then we've had two more incidents of the car running fine then the next time we go to start it it's completely dead. When it happens it's completely dead, won't start, no interior lights, can't even use the power door locks. In each case after pulling the battery cables and reattaching them the car starts right up. It doesn't appear to be the charging system since after reconnecting the battery it is obviously charged up and able to perform.

My thought is that this sounds like a relay or switch that's hanging up, then when it's de-energized by disconnecting the battery it resets and all is well until it hangs up again. I went over to my local Ford dealership and talked to a service adviser who said given the description their next step would probably be to recommend changing out the starter relay and see if that cures the problem since it's so intermittent and not something you can reproduce on command. I bought the relay and am doing that now, but as I'm thinking about it, it doesn't make sense to me that the starter relay would kill power to the rest of the car too, affecting the doorlocks and interior lights. I'm hoping someone with more knowledge can tell me 1) would a bad starter relay have this affect; 2) if not, is there another relay that might; 3) finally, if neither of those is the case, what else might cause this type of issue.

 

Seen this issue numberous times. Normally cured by removing the battery terminals and cleaning the battery posts and terminal connectors real good with scotch-brite pad. Then apply a thin coat of dielectrical grease to the battery posts and terminals connectors. Then reconnect and snug the terminal connectors. Since the battery posts are lead and terminals connectors are tinned copper, you get electrolysis and over time, this causes high resistance. Popping the connectors off and on will provide a small clean surface area that will give you the "some times it starts and some times it doesn't" symptoms.

 

ABSOULTLY...Friend had the same problem, and just cleaning the terminal connectors did the trick...also check the Battery cables sometimes they are corroded