All,
I have 2000 Volvo V40 with the 1.9T engine. The car has 4 wheel disc brakes and ABS. The ABS light is off and when I jam on the brakes at speeds higher than 5mph on dry pavement, the ABS engages properly. My problem is that if I’m braking fairly hard and the car hits a bump or a pothole (not uncommon for Massachusetts), the ABS kicks in and I tend to lose braking ability for a second.
This behavior started about a year ago and has gotten progressively worse. Since the ABS light isn’t on, I’m reluctant to say it’s a wheel sensor, but I’m not sure what else to go after other than the ABS module, which is a pricey fix for a guess. Ideas?
I should add that the car has new pads and rotors on all four wheels, and all four tires are in good condition. Brake fluid looks clean, too.
You might want to have the struts inspected.
If the struts are worn where they no longer hold the tires to the road when/after hitting a bump, the tire will stay suspended in the air longer. Since the tire isn’t on the road, there’s no rolling force applied to the tire. This then allows that brake to lock up easier. Since the ABS is designed to prevent locking up of the brakes, it’s going to engage the ABS under these conditions.
Tester
Agree with tester, it sounds like the ABS is operating properly. Perhaps there are more potholes, or bigger potholes?
Changes in the suspension due to age and miles is a likely cause for the tires not staying on the pavement as well now as in the past. Tires can affect the ABS function too if one of them is worn or air pressure is too low. It is like a chain, the weakest link breaks first. The tire with the least traction will slip and that activates the ABS system and you loose your braking power. Are the tires the current tires the same brand as you had before?
Still another possible is there is more loose dirt and stuff on the road. After spreading salt and sand to improve grip in winter the roads have this stuff left over and particulary in curves and intersections. The issue is traction and perhaps it is an issue with the roads and not the vehicle. In my area there seems to be much more loose gravel and sand on the roads than normal for this time of year. I wonder if budget cuts and the economy are impacting this area of road maintenance?
Heh, of all the things you could have said, I hate this option the most. This car has had so many suspension problems it defies belief. Apparently Volvo had a bad spring casting and I’ve had to replace all four coil springs, both rear shocks and the right front strut as well as the top strut mounts on both sides twice. It didn’t help that the car was driven over a pothole big enough to crack two rims in half a couple years ago. So, that points to the left front strut as a possible culprit since I already replaced the right one. Ok, I’ll take a look at it and let you know. Thanks guys!