Dead battery

[DavidL]

I had a problem last week with my power locks not working but wasn't able to figure out what the problem was:

http://www.automotiveforums.com/vbul...d.php?t=659448

Now I'm having a problem with my battery going dead. Do you thing the two things could be related? The battery recharges while driving, but if the car sits for a couple of days, the battery loses its charge. I have disconnected the cables and cleaned the terminals. Also, I took the car to Advance Auto to have the battery checked. They said it tested okay, but I'm not sure how old this battery is (bought the car used 3 1/2 years ago). Is it possible their check was wrong?

[Huney1]

"Is it possible their check was wrong?" I doubt it because they test the alternator output and battery load test. One way you can check is when you're going to leave it sit a couple days take the negative battery terminal loose then after it sits hook it up and if it cranks OK then you have something in the car draining the battery and if it's dead you know the battery is bad.

Another check: With everything off, disconnect the negative cable and put a volt meter between the -battery terminal and cable and see how much juice is flowing and Shorod or one of the pros can tell you if it is to much juice.

I see you have a 99 and if the battery has never been replaced I'd say its time. My 03 battery died a few months back and had to get a new one.

[shorod]

I don't put much faith in the battery tests that the chain auto parts stores do. I had a co-worker get his battery load tested and he was told it was fine. However, when he tried to start the car, it turned over quite slowly. I put my meter across the battery and it would drop below 9V on a start attempt. I then put my current probe on the positive cable and the current draw was not abnormally high. He picked up and installed a new battery. His slow cranking went away. We verified there was not a current drain discharging the battery, and he's had no problems for the past 2 years with it.

If you don't have a multimeter, but do have a test light (one or the other is almost a necessity for troubleshooting electrical issues), install the test light in series with a battery cable and see how brightly the test light glows (as Huney1 suggested). While doing this, make sure all doors are closed, the trunk is closed, the key is off, glove box is closed, and if you have a hood light, remove the bulb. Basically, anything that could be drawing current with the key off should be in the "off" state. If the test light glows brightly and, even after 20 seconds, is still glowing quite bright, you probably have a drain somewhere.

If you have a current meter, then install it in place of the test light, but be very sure to not open a door or something with the meter installed if it is rated for less than 10 amps. You will blow the fuse in your meter.

I would expect your current draw with everything off to be around 70 mAdc or so (0.070 Amps DC). If it is much higher than that, you probably have a parasitic drain somewhere.

If the battery drain seems reasonable, then install the battery cable onto the battery, switch the positive lead on you multimeter to read "Vdc" and measure the battery voltage. Have someone attempt to start the car with the meter still reading battery voltage. If the voltage drops to below 9.5 Vdc during the start attempt, consider replacing the battery.

-Rod

[DavidL]

Thanks for the suggestions. I'll check these things out.

[Huney1]

When a battery is cold it doesn't have the amps (cranking power) a warm one does.
If you don't have starting problems in warm weather you may need a new higher amp battery.
The one you have may not have enough amps to turn over the engine when it is cold.
Batteries have ratings so get one with high amp cranking power. Also use a light wieght oil like 5W-20 because the thicker the oil the harder it is to turn over a cold engine.

[Scrapper]

when you take neg cable off take and touch it to battery if big spark..you have a short some where make sure everything is off in car and door is closed.

[DavidL]

I finally had a chance to look at the car again. It looks like the problem with the power locks (that I mentioned in my first message) is also causing the battery to go dead. When I do the check with the meter set on 10 amps, it pretty much maxes out the meter. When I pull the #4 fuse in the box under the hood, it stops the current. Just to confirm it, I have had the fuse pulled for a few days, and the battery is still good. Also, when I put the fuse back in, I can hear a noise in the doors that sounds like it's coming from the locks. It's like putting power back on the circuit causes the motors to "jump" or something, but the locks don't move. Any suggestions for how to track it down from here? I'm ready to take the panel off the door if that's what it takes.

[DavidL]

Okay, I've done a little more exploring. I located the RAP module and unplugged it. The current draw stopped, and the locks now work with the door switches (except for the passenger door lock, which is probably a different issue).

There is a black box with three relays mounted on the the same bracket as the RAP. When I use the door switch to lock the doors, one of the relays clicks. When I unlock the doors, the second relay clicks. With the RAP plugged in, the first relay clicks when I push the lock button, but the locks don't move. The second relay doesn't click at all. (The third relay is for the trunk lid release.)

Does this mean the RAP is the problem? The odd thing is that the remote still works for the trunk lid release. It seems like that wouldn't work if the RAP is bad.

I got the part number off the RAP module and tried to look it up online, but the Ford parts database doesn't recognize it. It's F87F-15K602-AA. I have double- and triple-checked to make sure I read it correctly.

[shorod]

Looks like the RAP module runs $128 from Fast Parts Network (http://www.trademotion.com/partlocat...99&catalogid=1)

Seems like it may be worth pulling the RAP module apart and checking for obvious shorts.

-Rod

Originally Posted by DavidL

Okay, I've done a little more exploring. I located the RAP module and unplugged it. The current draw stopped, and the locks now work with the door switches (except for the passenger door lock, which is probably a different issue).

There is a black box with three relays mounted on the the same bracket as the RAP. When I use the door switch to lock the doors, one of the relays clicks. When I unlock the doors, the second relay clicks. With the RAP plugged in, the first relay clicks when I push the lock button, but the locks don't move. The second relay doesn't click at all. (The third relay is for the trunk lid release.)

Does this mean the RAP is the problem? The odd thing is that the remote still works for the trunk lid release. It seems like that wouldn't work if the RAP is bad.

I got the part number off the RAP module and tried to look it up online, but the Ford parts database doesn't recognize it. It's F87F-15K602-AA. I have double- and triple-checked to make sure I read it correctly.

[DavidL]

Just to finish the story (better late than never), I found a used RAP module on Ebay for $20. I installed it and the remote entry works now, and the battery is fine.

[shorod]

Glad to hear you got your problems fixed, and for $20! Thank you for the follow-up!

-Rod