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Mysterious Battery Drain. Double check my conclusion?
Ever since I got my FB running again after a ~2 year restoration the battery has had a severe drain. It can be completely dead in 48 hours. I swapped in an S5 engine with a Haltech and in the process I built my own engine harness, but left the original body harness and interior harnesses completely untouched.
I started troubleshooting by removing the battery and check continuity between the positive battery lug and the engine block (ground point), and I had continuity. Definitely a problem somewhere. I pulled fuses and lost that continuity when I pulled the 15a 'hazard' fuse under the dash. Following the wiring diagram, I then put the fuse back and unplugged the x-04 connector under the dash, and my continuity to ground returned. I also removed the 15a fuse and left the x-04 connector undone and tested continuity between the hazard pin on the connector and the firewall, and I got continuity. So my conclusion is that somehow my original, untouched body harness has developed a ground to the backside of the firewall between the fuse box and the x-04 connector, as improbable as that sounds. Am I right?
Below is the diagram excerpt. I pulled the fuse labelled 'hazard' in red. The LY[f] wire between the fuse and x-04 seems to be the problem...
Assuming I'm right, how hard is it to get that section of wiring out? It looks like a nightmare and I am tempted to run a new, separate wire
May not be the direct prob, but can contribute to all sorts of electrical gremlins:
Have you ever changed out the (+) and (-) main battery cables?? These can 'look' fine and be shot inside!
May not be the direct prob, but can contribute to all sorts of electrical gremlins:
Have you ever changed out the (+) and (-) main battery cables?? These can 'look' fine and be shot inside!
Stu A
80GS
AZ
I just made new ones last week to see if it resolved this problem, which it didn't but was still a good investment!
When you say you fitted a series 5 engine, I assume complete with alternator? If so, did you modify the charging circuit to suit when you re-wired? If you keep the standard 1st gen design, the "S" terminal of the new alternator is wired hooked to ignition 12V+ instead of battery 12V+ which is what the s5 alternator wants. Without correcting this you will get the same kind of parasitic drain you describe.
When you say you fitted a series 5 engine, I assume complete with alternator? If so, did you modify the charging circuit to suit when you re-wired? If you keep the standard 1st gen design, the "S" terminal of the new alternator is wired hooked to ignition 12V+ instead of battery 12V+ which is what the s5 alternator wants. Without correcting this you will get the same kind of parasitic drain you describe.
I did recently install an S5 alternator and I wired it correctly (at least I think so, I followed instructions on this forum) however the issue with drain started before I swapped the alternator. I originally got the car running with the GSL-SE 60amp alternator but it seemed unhappy running with the headlights on so I upgraded
I wound up replacing the Blue/Yellow wire shown in the diagram above between the fuse box and x-04 connector like I planned and it's working fine now. I just let the car sit for 4 days and it started right up again with a solid charge. I did not pull out the original harness in the dash but instead ran a new wire along the outside and zip-tied it on the back.
11-23-21, 11:52 AM
