Contour Enthusiasts Group Archives Forums General Troubleshooting Problems with ABS on '98 SVT Contour

The ABS on my 1998 SVT Contour is not working correctly this winter (it has worked fine previously). If there is only slight slip (1 or 2 wheels), the ABS works correctly. But if there is lockup at all 4 wheels, the ABS just quits working (the lights dim a lot, too). I've measure Voltage at the battery, and had about 11.5V when this happens. The car has a new battery and new alternator - the charging system seems to be in order. There are no other electrical problems. The ABS passes the self-test on start-up, and the ABS light does not light when this error occurs. Any thoughts? The repair manual does not offer a lot of insight into the ABS unit, other than testing the relays.

That's wierd about the draw...

I did notice that my ABS stops working if the tires spin a lot... The light will come on and stay on for a few hours, then it'll reset itself or something and be good to go!

How's the battery voltage at idle, no acessories, is it 13.8 to 14.8 volts? Should be above 14 on colder days.

As far as I know, the brake fluid has never been flushed. I absolutely hate bleeder screw, too - just got done trying to break one free on an '82 Tercel, and couldn't get it to budge even with an acetylene torch! Wound up bleeding it at the brake line instead...

Funny you should ask, because here's the rest of the story! About 2 months ago, my batter completely died without warning. It had just enough voltage to illuminate the gauges, so I push-started the car (I was about 15 miles from home and it was late at night) and limped her home (which she was not happy about at all - the engine kept trying to die every time I tried moving from a dead stop).

After I installed a new battery, I noticed that the voltage fluctuated quite a bit from idle to above 2500rpm (lights would go from dim to bright, which I never noticed before), and that the lights flickered at low RPM's with all accessories on (blower, rear defogger, lights, etc) when it was cold out (below freezing).

I tested the voltage at the (new Die Hard) battery with a voltmeter, and it was 14.5 V on a cold start, 12.5V with all accessories and lights on. AutoZone checked it, too, and said that the alternator was good, but I didn't like the lights flickering when it was cold outside (figured that a diode was bad or dying). So I cleaned all the battery terminals and replaced the alternator! No more flickering lights at cold temperatures (below freezing), and my voltages are still good, but the ABS still doesn't work if I lock up all the wheels (it works if only 1 wheel slips, though). It's just like the ABS pump shuts down (either that or the ABS pump is drawing too much amperage and the charging system shuts down, but I still think the ABS should work even if the engine's not running).

It doesn't matter what RPM the engine is at, either - the ABS just flat gives up if you lock up all the wheels. It wouldn't be so bad, but it kinda pumps up the pedal before it quits, so modulating the brakes is difficult once it quits working. It'd be easier if I just pulled the ABS fuse, but I hate driving with idiot lights on all the time.

Anyways, the battery and charging system are definitely in good working order. But it sounds like I should bleed the brakes and flush some new fluid through the system, like maybe that would help.

Any other theories on this one or advice?

Are you still reading 11.5 volts on the battery when this happens? If you are, you still have an electrical problem of some sort. I would try substituting a know good battery. Ocassionally batteries fail in very wierd ways.

My ABS doesn't like it when I play in the snow with the e-brake.