ABS light

Need technical Q/A then you're in the right place

Moderator: martauto

ETERNITY
E30 Zone Camper
E30 Zone Camper
Posts: 1402
Joined: Thu Apr 23, 2009 11:00 pm

Post Thu Jun 26, 2014 12:06 pm

I had a flat battery and then once I got the car running the abs light appeared.

6 months prior to this I had the abs relay replaced.

any idea?
325i sport tech 2, lach silver, 1989, BBS RS 16 split rims,

[URL=http://s878.photobucket.com/user/ETERNI ... 0.jpg.html][img]http://i878.photobucket.com/albums/ab35 ... 46cc30.jpg[/img
User avatar
Brianmoooore
E30 Zone Team Member
E30 Zone Team Member
Posts: 49359
Joined: Mon Jan 10, 2005 11:00 pm

Post Thu Jun 26, 2014 1:22 pm

Sounds like the relay may have done what it was designed to do - protected the ABS ECU from electrical spikes. Unfortunately, it was designed to be a 'one shot' device, giving up its life in the process.
How did you "get the car running" after the flat battery.
ETERNITY
E30 Zone Camper
E30 Zone Camper
Posts: 1402
Joined: Thu Apr 23, 2009 11:00 pm

Post Fri Jun 27, 2014 12:58 pm

I used jump leads. So I have to replace the relay again
325i sport tech 2, lach silver, 1989, BBS RS 16 split rims,

[URL=http://s878.photobucket.com/user/ETERNI ... 0.jpg.html][img]http://i878.photobucket.com/albums/ab35 ... 46cc30.jpg[/img
User avatar
Brianmoooore
E30 Zone Team Member
E30 Zone Team Member
Posts: 49359
Joined: Mon Jan 10, 2005 11:00 pm

Post Fri Jun 27, 2014 3:13 pm

ETERNITY wrote:I used jump leads. So I have to replace the relay again
That would do it! These things are an absolute menace with modern cars!
There is a zener diode inside the relay which goes permanently short circuit in the case of a serious power surge, but it should have survived a minor one caused by the use of jump leads.
The diode will have blown an internal fuse link in the course of doing its job though. This link is not designed to be replaceable, but with a bit of ingenuity and a soldering iron, it's possible to replace it with an externally mounted 7.5A blade fuse.
I suspect these fuses are slower acting than the original, so if you do it again, you probably will kill the zener diode.