Hi all, its my first post here and I'm by no means a mechanic so apologies in advance if I make some faux pas, but hello! :) 

I've been scouring this forum and Youtube to try and help with my issue but I've ran out of ideas so I'm hoping someone can help. My car (2009 Diesel mondeo 2.0L Titanium X) has a massive parasitic drain that is completely killing my battery ( i installed a new one and in under a week and stationary on the drive it went from fully charged to 0.2V). I've plugged a multimeter in series with the battery to test and its showing >10A draw when the ignition is off. I've pulled fuses to see which circuits are bad, and I get roughly 13A across the R8 and R11 relays for the front windscreen wiper motor and >10A draw on the fuses that supply the passenger and luggage comp fuse boxes. I also believe that the rectifier in my alternator has gone since I replaced the battery to test whether it was just a rubbish battery as I get a current in both directions when testing across it with my meter on diode selection. 

I pulled the wiper motor out and it still showed the 13A draw acros each of the R8 and R11 relays, so I tested the relays themselves and they all work fine. I've pulled the radio, hunted for aftermarket mods and done everything I can possibly think of or find online to find the source of the drain. I eventually brought an OBDII reader and downloaded forscan, which is showing a bunch of DTCs and I'll be honest I'm not sure what to make of it. After looking on here I'm not sure whether it looks like it might be a faulty module itself or whether other working parts of the car is the true issue but I'm at a loss of how to continue troubleshooting.

I'm a student so trying to do this on the cheap by learning myself, so any advise (even if its to cut my losses) would be greatly appreciated. I've attached the DTC codes present on the test I ran for reference. It seems like most of them are ABS related but then on the advise sections it says about faulty charging system being a potential cause and so I'm not sure whether its just because the alternator might be knackered! I don't want to replace the alternator only to find theres some horrible short circuit anyway and the cars a write off 😞

Thanks all!

Alex

mondeo7-7test.txt

9 minutes ago, Hughesymendes said:

i installed a new one and in under a week and stationary on the drive it went from fully charged to 0.2V

Well that's killed that battery. It will never fully recover no matter how much or how long you charge it.

10 minutes ago, Hughesymendes said:

I've plugged a multimeter in series with the battery to test and its showing >10A draw when the ignition is off.

That's a serious amount of current if you are measuring it correctly. Most multimeters have the current range fused at 10A maximum.

12 minutes ago, Hughesymendes said:

I also believe that the rectifier in my alternator has gone since I replaced the battery to test whether it was just a rubbish battery as I get a current in both directions when testing across it with my meter on diode selection. 

I'm not sure how you can be fully testing the 3 phase rectifier of your alternator without removing it and opening up alternator to gain access to the 6 diodes. I think you may be not be getting a correct reading, although a failed diode in the alternator would cause a significant current draw on the battery.

6 hours ago, Hughesymendes said:

and done everything I can possibly think of or find online to find the source of the drain.

Here's a good video on methods for finding parasitic draws:

 

6 hours ago, Hughesymendes said:

I've plugged a multimeter in series with the battery to test and its showing >10A draw when the ignition is off.

Jeez, I hope you didn't and don't try to turn the ignition on in that setup. As unofix says, most multimeters only support measuring up to 10A. Some, like the ones I have, support 20A. (You've also got to check the measuring capacity of the probes, which may or may not match that of the meter). In the best case scenario your meter will have a good sand-filled fuse that'll blow safely and can be replaced. Many won't have even a basic glass fuse though.

If you google how much current a starter motor draws, the results say hundreds! I've just recently got a clamp meter (which can measure much higher currents) and having just gone out to my car out of curiosity, I measured just the battery chassis wire and saw about 60A when starting the vehicle.

6 hours ago, Hughesymendes said:

is completely killing my battery ( i installed a new one and in under a week and stationary on the drive it went from fully charged to 0.2V)

As unofix says, you may have trouble getting that battery recharged now. Some battery chargers will refuse to charge if the voltage has fallen below a certain level. In those cases you can trick the charger by hooking up a small 12v battery. However if it's been severely discharged as you suggest it has, then it may prove very difficult if not impossible to recover. Have a read of this: https://www.batteriesplus.com/blog/power/revive-a-dead-car-battery

6 hours ago, Hughesymendes said:

I also believe that the rectifier in my alternator has gone since I replaced the battery to test whether it was just a rubbish battery as I get a current in both directions when testing across it with my meter on diode selection. 

If your alternator's diode pack has become faulty, allowing current to flow in the wrong direction, then this could be the cause of the drain.

Why, if that's the case, you're getting large current flow across the relays and fuses you mention, presuming you're performing the measurements correctly, I'm not sure. I'd suggest disconnecting your alternator to check if that alone solves the problem, but you've killed your new battery so unless you manage to get it charged up, you'd have to get another before you can test again.

6 hours ago, Hughesymendes said:

I've attached the DTC codes present on the test I ran for reference.

Looking through the list of DTCs it's an unhelpful mess. Some are obviously related to low battery voltage. Others could be due to modules failing to operate properly as the voltage level has dropped to below the point where they can function properly. I don't think it's going to be too helpful focussing on them at this point.

 

How I suggest you proceed:

1. Disconnect your alternator. Take great care not to allow the red power cable to come into contact with any other metal. This'll take it out of the equation. (Not that much power will flow with a dead battery, so little danger currently, but it could be a big danger later if you reconnect a new battery and forget to isolate that loose cable).
2. Get that battery recharged, if at all possible, or otherwise get yet another new battery (and this time don't let it get so discharged).
3. Recheck for parasitic draw (with no alternator connected). (Maybe there's shorted wiring or a faulty module somewhere).
4. If there's then no parasitic draw and the alternator's rectifier is definitely faulty, you can assume that's the only fault and replace it.
5. If there's still a parasitic draw without the alternator, replace the rectifier anyway if faulty, and work on tracking down the other faults. Get that mess of unhelpful codes cleared and recheck with the voltage problem solved, maybe then something in what's left may help if needed.

13 hours ago, rd457 said:

Here's a good video on methods for finding parasitic draws:

 

Jeez, I hope you didn't and don't try to turn the ignition on in that setup. As unofix says, most multimeters only support measuring up to 10A. Some, like the ones I have, support 20A. (You've also got to check the measuring capacity of the probes, which may or may not match that of the meter). In the best case scenario your meter will have a good sand-filled fuse that'll blow safely and can be replaced. Many won't have even a basic glass fuse though.

If you google how much current a starter motor draws, the results say hundreds! I've just recently got a clamp meter (which can measure much higher currents) and having just gone out to my car out of curiosity, I measured just the battery chassis wire and saw about 60A when starting the vehicle.

As unofix says, you may have trouble getting that battery recharged now. Some battery chargers will refuse to charge if the voltage has fallen below a certain level. In those cases you can trick the charger by hooking up a small 12v battery. However if it's been severely discharged as you suggest it has, then it may prove very difficult if not impossible to recover. Have a read of this: https://www.batteriesplus.com/blog/power/revive-a-dead-car-battery

If your alternator's diode pack has become faulty, allowing current to flow in the wrong direction, then this could be the cause of the drain.

Why, if that's the case, you're getting large current flow across the relays and fuses you mention, presuming you're performing the measurements correctly, I'm not sure. I'd suggest disconnecting your alternator to check if that alone solves the problem, but you've killed your new battery so unless you manage to get it charged up, you'd have to get another before you can test again.

Looking through the list of DTCs it's an unhelpful mess. Some are obviously related to low battery voltage. Others could be due to modules failing to operate properly as the voltage level has dropped to below the point where they can function properly. I don't think it's going to be too helpful focussing on them at this point.

 

How I suggest you proceed:

1. Disconnect your alternator. Take great care not to allow the red power cable to come into contact with any other metal. This'll take it out of the equation. (Not that much power will flow with a dead battery, so little danger currently, but it could be a big danger later if you reconnect a new battery and forget to isolate that loose cable).
2. Get that battery recharged, if at all possible, or otherwise get yet another new battery (and this time don't let it get so discharged).
3. Recheck for parasitic draw (with no alternator connected). (Maybe there's shorted wiring or a faulty module somewhere).
4. If there's then no parasitic draw and the alternator's rectifier is definitely faulty, you can assume that's the only fault and replace it.
5. If there's still a parasitic draw without the alternator, replace the rectifier anyway if faulty, and work on tracking down the other faults. Get that mess of unhelpful codes cleared and recheck with the voltage problem solved, maybe then something in what's left may help if needed.

Thanks for the helpful reply! I've acctually watched that exact video (I've watched a lottttt of videos and tested fuses and common suss equipment from videos like the bluetooth module and radio etc) 🙂

I certainly didn't try and power on don't worry haha. I had the car in its key off state to try and get the modules to shut down so that I could get accurate readings but its now just maxing out the current reading on two separate meters (10A sensitivity and just spikes up then says 1. which the manual states is maxed out). I left it for about 20 minutes to see if it would go down but it doesn't. 

I should have clarified in my initial post but I've replaced the battery as I couldn't get my smart charger to charge (or even identify) the battery. The above tests were done with the alternator detached. Both the main power loom and the small power cable that communicates with the car (unsure of the module sorry!) were detached with the power loom insulated to ensure it didn't short, so I'm pretty sure there is a drain elsewhere. I think thats what caused the alternator to go, as I read constant cycling of a battery (as it initially kept going dead) can weaken the diodes as the alternator has to work harder, and then when the battery is replaced it can break them. I only started having issues with that after replacing the battery so I'm guessing it was that! I ended up disconnecting everything from the battery (ie the alternator and stripped every fuse + relay in the engine fusebox) and then plugged them in one by one to see where the current would pick up. When it did I left it for a few minutes to see if it would power back down and if not I noted the amount and the fuse, left it disconnected and moved on until I had as full a fusebox as possible with no current draw. That was how I noted the r8 and 11 relays as plugging them in immediately spiked the current to between 13-15A.

With regards to the codes, that was running the diagnostic reader on a brand new battery that was only installed a week ago so I'm not sure why its getting low voltage readings? I've tested the battery voltage and its showing 12.6V and the car is capable of starting first time, I've only had it connected to run tests to try and track down the source of the drain. 

At this point I'm at 'stage 5' but as you say, the DTC codes are an unhelpful mess!

 

19 hours ago, unofix said:

Well that's killed that battery. It will never fully recover no matter how much or how long you charge it.

That's a serious amount of current if you are measuring it correctly. Most multimeters have the current range fused at 10A maximum.

I'm not sure how you can be fully testing the 3 phase rectifier of your alternator without removing it and opening up alternator to gain access to the 6 diodes. I think you may be not be getting a correct reading, although a failed diode in the alternator would cause a significant current draw on the battery.

Yeah I replaced it immediately as I knew it was dead and my trickle charger wouldn't even identify it, would just error out saying no battery attached. 

 

To test the alternator I isolated it from the car (in situ, just unplugged the power loom and the smaller 12V cable) and then tested using my digital multimeter set to diode test. Putting the live on the live connection and then grounding the common, looking for a reading and then switching the probes round. With live on the live connection you should get no reading but I got a reading in both directions showing one or some of the diodes must have failed? With the alternator plugged in and no fuses connected I got a 5A draw from the battery too, however with the alternator disconnected and isolated I still got a +10A draw. 

4 hours ago, Hughesymendes said:

With regards to the codes, that was running the diagnostic reader on a brand new battery that was only installed a week ago so I'm not sure why its getting low voltage readings? I've tested the battery voltage and its showing 12.6V and the car is capable of starting first time, I've only had it connected to run tests to try and track down the source of the drain.

Oh okay. You need to manually clear codes to get a clean slate. That'll get rid of all the old stuff relating to the previously dead battery.

4 hours ago, Hughesymendes said:

I should have clarified in my initial post but I've replaced the battery as I couldn't get my smart charger to charge (or even identify) the battery. The above tests were done with the alternator detached. Both the main power loom and the small power cable that communicates with the car (unsure of the module sorry!) were detached with the power loom insulated to ensure it didn't short, so I'm pretty sure there is a drain elsewhere. I think thats what caused the alternator to go, as I read constant cycling of a battery (as it initially kept going dead) can weaken the diodes as the alternator has to work harder, and then when the battery is replaced it can break them. I only started having issues with that after replacing the battery so I'm guessing it was that! I ended up disconnecting everything from the battery (ie the alternator and stripped every fuse + relay in the engine fusebox) and then plugged them in one by one to see where the current would pick up. When it did I left it for a few minutes to see if it would power back down and if not I noted the amount and the fuse, left it disconnected and moved on until I had as full a fusebox as possible with no current draw. That was how I noted the r8 and 11 relays as plugging them in immediately spiked the current to between 13-15A.

Okay, that's made things clearer, thanks.

4 hours ago, Hughesymendes said:

I ended up disconnecting everything from the battery (ie the alternator and stripped every fuse + relay in the engine fusebox) and then plugged them in one by one to see where the current would pick up.

There's also another fusebox in the passenger footwell (CJB, aka BCM/GEM). Unplugging modules & sensors could also help, especially the BCM.

4 hours ago, Hughesymendes said:

and then plugged them in one by one to see where the current would pick up. When it did I left it for a few minutes to see if it would power back down and if not I noted the amount and the fuse, left it disconnected and moved on until I had as full a fusebox as possible with no current draw. That was how I noted the r8 and 11 relays as plugging them in immediately spiked the current to between 13-15A.

Okay so yes you obviously seem to have a fault on something common to those circuits then. Question is what. It would be ideal if we had wiring diagrams to consult but I don't think we have any for a Mk4 Mondeo, so the best we can do is hope things are organised similar to a vehicle of similar age.

---

Going back over the list of DTCs, ignoring those relating to voltage, we're left with the following ones of possible interest:

• ABS C1A92 - Left Rear Wheel Speed Sensor - Circuit Current Out Of Range
• ABS C1A93 - Right rear wheel speed sensor - Circuit Current Out Of Range
• BCM B1097 - Heated Windshield Relay - Circuit Short To Ground Or Open
• BCM B10AF - Blower Fan Relay - Circuit Short To Ground Or Open
• BCM B1133 - Heated windshield LED - Circuit Short To Battery
• BCM B1C84 - Heated Rear Window Relay Output - Circuit Short To Ground Or Open
• BCM B1D17 - Battery Backed Sounder - Component Internal Failure
• PDM B1165 - Left Front Puddle Lamp Output - Circuit Short To Battery Or Open
• DDM B1166 - Right Front Puddle Lamp Output - Circuit Short To Battery Or Open
• RFA B10E7 - Ignition On Relay - Circuit Short To Battery
• RFA B11E8 - ABS Power Supply - Circuit Short To Ground
• RFA U3004 - Accessory Power Relay - Circuit Short To Battery
• IPC U0415 - Invalid Data Received from Anti-Lock Brake System (ABS) Control Module 'A'

Only the last one was actively present at the time of the scan, but is probably just related to ABS module power supply issues. It's interesting that both rear ABS sensors have current range issues, but perhaps the current is simply too low due again to power supply issues. Let's put the ABS stuff to one side for now.

As to the rest, there's a lot of stuff relating to the BCM here. Heated windscreens are controlled by the BCM (or at least are for my Mk2.5 Focus). Lights tend to be. The windscreen wipers too. Another common factor is the fusebox in the engine bay of course which could have a fault internally, but given that the Mk4 Mondeo is susceptible to water ingress in the BCM, I'm suspecting that this will be the problem. See the below video: