I’ve got a head scratcher. I have a Honda dc2 integra type r uk model with an electrical problem.
It has no obvious symptoms other than a long standing parasitic drain issue that only reared it’s head once I stopped using it daily. A couple of weeks ago the battery wouldn’t hold charge and would drop to 10v after 24 hours of being charged and not connected to the car. I got it replaced under warranty but obviously there’s an issue that caused it that needs to be fixed. I suspect there is a short but I’m no electrical guy, more mechanical.
I put a multimeter between the negative terminal and negative battery clamp to measure voltage. In the past it would say around .6v and would drain the battery over a few days or less in winter. Now after killing the battery it shows the full 12.6v with the multimeter in series with the negative battery terminal and clamp.
I’ve been mucking about with this for a couple weeks and now I suspect I might have been measuring things incorrectly… but I’m not sure. Should I be checking it in this way, multimeter in series on negative terminal to read the volts? My assumption is that if all is correct and no short is present the multimeter should be reading close to 0v?
I have cleaned the ground strap from engine to chassis and fitted another one nearer the gearbox in addition to the existing one that looks old and is inaccessible.
The car has two fuse boxes, one by the battery and another under the dashboard. I’ve pulled all the fuses, most relays (some have covers on I can’t get off) and unplugged everything in sight one by one that I’ve been able to.
The battery has three leads from the positive terminal, one to the starter, one to the fuse box and another to the abs unit.
The main 100amp battery fuse drops the voltage to 0.3v when pulled. The 40amp ignition fuse drops the voltage by 1v when pulled out and 15amp radio backup drops about .5v when pulled. There is no change from any of the fuses under the dash being pulled. There is one big plug with a bunch of wires that drops the voltage a small amount but I don’t know what it links to as I’ve not been able to trace it (it’s tight under the dashboard)
I assumed that the ignition may be at fault in some way as that fuse and radio/backup appear to be affected. I disconnected the aftermarket alarm by pulling the two fuses spliced to the ignition switch and disconnected the ground in case that was at fault. No change. Unplugged the ignition switch cables all together and no change.
The radio has been disconnected and that drops the voltage in the same way the fuse does, just by about .5v Disconnected the powered dab aerial which was linked to the 12v supply for the rear lights and no change.
Have disconnected the alternator and starter but that didn’t change anything. Alternator diode is good as polarity shows only in one way and reads a good voltage raise when engine is running. The starter has it’s own supply direct from the battery and was not affected by pulling the 100amp battery fuse. When the battery fuse was removed the voltage dropped to around .3v
Now a few days ago when pulling the battery fuse the multimeter still read 12.ish v. The only other thing attached to the battery is the starter and abs unit. Disconnected the starter again and it drops to around 5-7v and raises again to 12v when touched to the starter. Disconnecting the abs does nothing to change anything.
The only thing that changed here was that I started the car to make sure it was still starting ok after disconnecting the alarm and ignition switch.
Since then it reads 5-7v ish as above. So I guess this is a short as The battery is only really linked to the ground at this point.
I really am stumped on this, I think I may have found the issue then nothing seems to affect the reading on the multimeter.
Any one have any ideas and am I going about this the right way?
It has no obvious symptoms other than a long standing parasitic drain issue that only reared it’s head once I stopped using it daily. A couple of weeks ago the battery wouldn’t hold charge and would drop to 10v after 24 hours of being charged and not connected to the car. I got it replaced under warranty but obviously there’s an issue that caused it that needs to be fixed. I suspect there is a short but I’m no electrical guy, more mechanical.
I put a multimeter between the negative terminal and negative battery clamp to measure voltage. In the past it would say around .6v and would drain the battery over a few days or less in winter. Now after killing the battery it shows the full 12.6v with the multimeter in series with the negative battery terminal and clamp.
I’ve been mucking about with this for a couple weeks and now I suspect I might have been measuring things incorrectly… but I’m not sure. Should I be checking it in this way, multimeter in series on negative terminal to read the volts? My assumption is that if all is correct and no short is present the multimeter should be reading close to 0v?
I have cleaned the ground strap from engine to chassis and fitted another one nearer the gearbox in addition to the existing one that looks old and is inaccessible.
The car has two fuse boxes, one by the battery and another under the dashboard. I’ve pulled all the fuses, most relays (some have covers on I can’t get off) and unplugged everything in sight one by one that I’ve been able to.
The battery has three leads from the positive terminal, one to the starter, one to the fuse box and another to the abs unit.
The main 100amp battery fuse drops the voltage to 0.3v when pulled. The 40amp ignition fuse drops the voltage by 1v when pulled out and 15amp radio backup drops about .5v when pulled. There is no change from any of the fuses under the dash being pulled. There is one big plug with a bunch of wires that drops the voltage a small amount but I don’t know what it links to as I’ve not been able to trace it (it’s tight under the dashboard)
I assumed that the ignition may be at fault in some way as that fuse and radio/backup appear to be affected. I disconnected the aftermarket alarm by pulling the two fuses spliced to the ignition switch and disconnected the ground in case that was at fault. No change. Unplugged the ignition switch cables all together and no change.
The radio has been disconnected and that drops the voltage in the same way the fuse does, just by about .5v Disconnected the powered dab aerial which was linked to the 12v supply for the rear lights and no change.
Have disconnected the alternator and starter but that didn’t change anything. Alternator diode is good as polarity shows only in one way and reads a good voltage raise when engine is running. The starter has it’s own supply direct from the battery and was not affected by pulling the 100amp battery fuse. When the battery fuse was removed the voltage dropped to around .3v
Now a few days ago when pulling the battery fuse the multimeter still read 12.ish v. The only other thing attached to the battery is the starter and abs unit. Disconnected the starter again and it drops to around 5-7v and raises again to 12v when touched to the starter. Disconnecting the abs does nothing to change anything.
The only thing that changed here was that I started the car to make sure it was still starting ok after disconnecting the alarm and ignition switch.
Since then it reads 5-7v ish as above. So I guess this is a short as The battery is only really linked to the ground at this point.
I really am stumped on this, I think I may have found the issue then nothing seems to affect the reading on the multimeter.
Any one have any ideas and am I going about this the right way?
