What's going on with my car...? Electrical madness

[Ben Lessani]

Hi guys,

Being a dab hand with the electrics, this shouldn't be much of an issue for me - but it certainly confused me a little. The other day, I returned to my car, to find the battery was totally flat - and usually, its pretty good. So I bump started it with the assistance of a fellow sales assistant, and went on my merry way (get it?). I parked up the car when I got home, pushed the lock button on the alarm, and to my surprise the stereo turned on Along with the fan and any other associated IGN accessories. I had no idea what was going on, so I just turned he alarm off then on again, and it all went off. I can only assume when I was in work, my stereo was just playing away flattening the battery - super odd.

Also, I always assumed my MFA was goosed due to the fact it showed my speed continually as about 12 mph regardless of setting, and my mpg was always about 6. I was driving round one evening and suddenly all the gauges just turned off (apart from speedo), and they just stayed off, I kept driving anyway, and went to lower my window (electric) and the gauges all turned back on again, and now, even better with a reasonably accurate mph figure (showed 75 mph when I was doing 90 mph). I could only assume its meant to be a trip average (not the total average one), rather than current speed. But unfortunately, my mpg is still super poo @ 6.

And now, even weirder, my electric windows only work when the drivers door is open The wiring for them is so little its untrue, its only a 12v run off the IGN on the fusebox, and a GND attached to the GND just above the fusebox. But they only seem to operate when the door push switch (for the door) is open. I have no idea whats going on, but I will certainly be looking into it.



If anyone has any ideas, great, if not, I'll figure it out when I strip the dash out (again!) on Sunday and see if I can figure out this electrical madness.

[Thom89]

Simple, just call your car "Christine" and be done with it!
Tom

[Mr Blue]

rain water entered and attacked fuse box???

[VapourTrails]

id check out the alarm and wiring also might have been a bodged up job. pull the lower dash off under the steering wheel and check all the wiring if like blue said water got in there ull see melted wires and burn marks, if thats the case id dare say that the car would either catch fire or not work at all. it cant think of anything else apart from the alarm and fusebox that would link these systems and the speedo is cable driven and will work without power so i doubt thats related.

[Ben Lessani]

im going to get my head under it tommorow and see whats going on, hopefully I'll suceed.

[Agreeable Slick]

Check all your earths first, and that the power cables from the battery are all ok.

[Uku]

aye and look for those awful scotch lock type clips alarms have a tendency to be fitted with , these cause havoc , my womens car had electrical faults just like yours , i found two scotch locks in the ignition loom had seperated the wiring over time and wiggling them knocked out all the lights and windows!. promtly removed them and soldered instead. just try wiggling any wires that were used when patching in the alarm , i suspect one of these is at fault.

[Ben Lessani]

Ok, half of the crazyness has stopped, windows work as normal and stereo doesn't appear to be turning itself on. I checked for a parasitic load (because I think the battery is ok), and something was drawing 0.34A - which is pretty high. So, I went through the fusebox removing them one by one until I the current dropped to 0, and it was fuse number 3 causing the problem.

Odd thing was (I wired the alarm in myself), the alarm was connected to it, cigarette lighter, along with the boot light and stereo! I just thought the wire I traced was run off the fusebox (doh!). So I'll rewire the lot with new fuses and proper connections to the fusebox! Anyway, turns out the parcel shelf wasn't located right and covered the top of the boot close switch, so the boot light wasn't turning off.

After sorting that, the load dropped to 0.11A which was the alarm itself - I suppose its what you get for a cheapo alarm, but it does have ultrasonics, shock sensors etc. So, I'll take a little bit more of a look at it.