Battery Drain problems. Wiring diagrams.

[nemo]

Where is a good source for car manuals and wiring diagrams. Looking for detailed information to troubleshoot a battery drain problem. Anyone use an online subscription service?

[redpoint5]

I don't have a source for that info, especially absent the make/model you're interested in.

That said, I find these things to be fairly easy to diagnose. Put a meter on the battery to see what the parasitic load is, then start pulling fuses until you find which one has an unreasonable draw. From there it's just a matter of locating the accessory on that circuit.

I found an aftermarket temperature sensor on my truck was drawing something absurd, like 150 mA. Once I threw that away my parasitic draw dropped to 5.5 mA, probably entirely my CD player.

[oil pan 4]

None.
Get an amp meter that will read DC amps down to 0.1.
Pull each fuse and stick the amp meter into the fuse contact points.
That's how I do it.

[Nedlom]

I don't have an answer on wiring diagrams, but this might be useful - was for me:

https://axleaddict.com/auto-repair/W...or-When-Parked

Never been able to find a decent wiring diagram for my vehicle - feels like the manufacturer wants to keep a secret, but then it's all canbus anyway so probably wouldn't make sense to me.

[Nedlom]

BTW my issue turned out to be point 5 "battery leakage" - something I didn't even know about. Dirty battery literally just leaking its charge out the case - I'd already done the pulling fuses thing looking for a parasitic draw, but found nothing.

[nemo]

Its the 2012 Fiesta.

If it were only as easy as pulling the fuses to locate the problem. In order to get the power drain to .01 amps.The radio fuse must be pulled .03 draw. While F6 (the body control module fuse for door locks) is out F28 (BMC for turn signals) must also be removed to drop it to .01. If F6 or F28 are pulled independently it will continue to draw .09. No other combinations yield the same result. Most likely something is wonky in the BMC but possibly some kind of feed back is causing the the BMC not to put those circuits to low power mode.

[nemo]

Originally Posted by Nedlom

I don't have an answer on wiring diagrams, but this might be useful - was for me:

https://axleaddict.com/auto-repair/W...or-When-Parked

Never been able to find a decent wiring diagram for my vehicle - feels like the manufacturer wants to keep a secret, but then it's all canbus anyway so probably wouldn't make sense to me.

Thanks for the link.

My source for that kind of stuff dried up. The information to the general public on the Fiesta is slim there are some auctions sites and some subscription services have manuals but have no idea if any are good. Interestingly I can find info on European models. My owners manual does not even seem to be correct, pull the fuse for the dome light and it still comes on.

[Nedlom]

Funny enough mine is a fiesta too - previous model to yours and UK spec though.
I've tried the auction sites and subscription thing - waste of money for me, its like ford won't let the info out into the public domain.

The systems all seem to be interconnected, with fail safes (?) built in.
I had a problem with the door ajar sensor - couldn't lock the car because it thought the door was open.
Pulled the Central locking fuse so I could lock it, but that made the indicators flash super fast - not straight away mind, but a few trips later.
Bypassed the door sensor so it always thinks the door is shut, then somehow it's figured it out again - if I open the door while moving I get a warning message.
It's like as if the canbus signal rerouts itself or something?
This is on a poverty spec model too (wind up windows, no power anything) I can only imagine its worse on newer, higher spec models.

I've given up on fault finding past checking for loose/dirty connections and damaged wires - anything else needs a computing degree 🙄

Merry Christmas btw

[teoman]

Did you try asking the car if it has a problem?

[oil pan 4]

Then if the fuse block trace doesn't work might need to use an amp clamp checking it at various times.