New alternator, fairly new batteries....after sitting 5 days or more, it cranks but no start.....put on charger for four hours, it fires right up...
Voltage on the multimeter shows 12.45 on both batteries......could there be something drawing down the amps? If so how do I find it?

 

Disconnect the negative battery cable, put your meter in series with the battery and negative cable, check the draw on amps.

 

Things to look at.
Any aftermarket stereo gear like an amp. Also alarm systems.




Sean

 

A buddy the other day was just telling me the switch to his seat was stuck, he was having the same issues, apparently his dog jumped in with muddy paws and mud was packed in the forward position , just another place to look.

 

Finding a draw can be a nightmare. You either need intimate knowledge of the electical system and how it works or some factory wireing diagrams both engine and body and a lot of luck. There are over 600 fused and relay circuits in the fuse boxes alone.[not all used] 3 circuits with inline fuseable links and several non fused circuits as well.
It can be a long drawn out process of elimination, very frusterateing.
Helm publishing makes the Ford manuals.

For the guy with the transit bus call Helm and see if they have released the current wireing diagrams yet. There has to be some somewhere otherwise how did they build the bus in the first place. May not be available for public purchase at the time you checked.

 

I do have a Garmin, after market radio and scan guage, however, they have been on here for over two years and this problem has just begun about a month ago.

 

Dual batteries and the delayed accessory circuit in the instrument panel makes testing a little more complicated. I suggest pulling the driver side (although it doesn't really matter which) negative cable off the battery first. Moving to the passenger side, loosen the negative clamp but don't remove it. Get your meter set up to measure amps and connect one lead to the driver side negative battery post and a bare probe on the other lead. Open the hood and drivers side door and leave open. When the interior lights go out you know the delayed accessory relay has timed out, when the under hood light goes off -that can take several minutes- the battery saver relay has timed out and your ready to take a measurement. Place the bare meter probe on the passenger side battery negative post and carefully slide the negative clamp up the post maintaining contact the whole way to the meter lead, then move the meter probe away from the battery post while maintaining contact with the negative clamp. If this goes correctly, you just switched power supplied without interruption and the under hood and interior lights will stay off and the meter will indicate parasitic draw. Should be less than 50ma or so. Obviously, if you want to pull fuses or do other testing while in this set-up you'll need to plan ahead and use clips for the temp connections.
The alternator is a common cause for battery drain, you may want to test it separately first.

 

Something else that can help cut down on diagnostic time is how big of a draw.
A lairge draw will limit the number of circuits you need to check.
Also keep in mind many DVOM can only handle 10 amp. Bigger than 10 amp you will want a amp meter rigged the same way Rusty described unles your useing a clamp-on that surrounds the wire.

 

My 2004 started the same thing several years ago and I found the drain stopped when insturment panel fuse was pulled (#38 irc and it includes windows, interior lights and a few others) I still havn't found exactly what item withing curcit is causing it. It could set a month without loosing charge if fuse was out. After tireing of pulling fuse I put a switch with in line fuse across that fuse position. The truck starts and runs fine with fuse missing but will turn check engine light on after a while. Many trucks had instrument clusters replaced under warranty (idk if this was the reason). After all that,your problem might be different but Rusty's approach is a good way to start.

 

I may haves found the drain, but now truck will not start. Left charger on to charge both batteries and I get crank but does not fire up.

 

I have the exact same problem with the instrument panel causing my my drain. If my truck is going to sit for more than a day I pull the fuse or connect a trickle charger. It will drain brand new batteries in a week of sitting to the point it won't turn over. I have heard of several others with the same problem.

 

The tech Got my truck started. He just shook all the wiring harnesses and it fired right up. He doesn't know what the problem is. The cam sensor checked out fine. Something kept it out of sync. He didn't really think it was the engine wiring harness but it could be chafing some where. He had me bring it home and drive it some to see if I can get it to do it again.