I recently took my car in for a brake inspection. They said I need new brakes and rotors. Last night I was driving and my ABS light and brake light came on (note surprised) and my speedometer dropped to zero while I was driving. Then, tonight my DSA light came on. I was wondering if the speedometer thing is related to the brake malfunction, or if my car has other issues with the computer?

 

I'm willing to bet you have a bad speed sensor, all of those systems rely on signals from the wheel speed sensors for one reason or another.
ABS to detect if a wheel is locked up
DSA to detect individual wheel speeds to compensate and maintain traction
Speedometer...well you get the idea.

I would check to see if the speed sensor or the wire going down to it is still intact and in good shape.

 

Another poster used the OBD2 port and a Bluetooth dongle to check for correct internal speed signals as a check.

 

What is a bluetooth dongle? Why wouldn't you just visually inspect the sensor and if it looks ok, then check continuity closed circuit=good open circuit=bad. I would stick to the simple tests rather than trying to decipher a wave signal from a proximity sensor.

 

I agree with NFowler, all of that together makes the speed sensor or the wiring from it culprit.

It wasn't any effort on my part to see whether or not I was getting the speed. I usually have DashCommand open when driving. Speedometer was off and I was still getting readings.

 

Hi All,

Picked up a 2001 S40 last night as our spare car. It has ABS and Brake light on. Speedometer and Odometer not working as well.

Check speed sensor first?

Any feedback would be much appreciated. Thanks

 

check brake fluid level first, then scan for any codes (need a good scanner that can do more than just power train codes). Sounds like it may be the ABS controller board which can develop cracks in the solder joints.

 

Here's what I was thinking of:

ELM327 OBD2 II Bluetooth Auto Car OBD2 Diagnostic Interface Scanner Tool FTSS | eBay

That, combined with a smart phone app like https://torque-bhp.com/, will tell you if the car's internal systems are correctly tracking speed.

 

Hello,

So i've been driving the S40 for a few days now. And what I've noticed at first start up in the morning, the speedo/odometer works for a few minutes and then it stops (lights go back on). It will not work all day til the next morning.

Thinking its time to take out the speed/abs sensors right?

 

I have this... It works! but doesn't do ABS or Readiness...

 

When I posted back in 2014 I waited a year and half before replacing the cluster and that fixed it. I had no ABS / brake lights and the cluster would just stop tracking speed.

If you can confirm that it's tracking speed correctly with ODB2 I would say the cheap fix is to investigate the cluster. The abs bits are a bit more expensive, even used. If you already have the info center goodies hooked up you need a cluster that has the info center also to keep that feature. Also if you have fog lights enabled you might need to re-enable them.

If you have a dice unit. You can monitor the wheel speed of all 4 at once while driving and can see if any of your speed sensors are wonky. Does the ABS light go on right away as soon as you start driving? I believe you need to reach a speed of 40mph before there is enough difference to detect that 1 of the 4 wheel speed sensors is at fault. I had a sensor wrong also which was all crudded up with gunk and was causing my speeds to be reported wrong on the cluster. Even still the OBD speed was accurate.

The abs unit also has a history of getting water into it / having the soldering points go bad and some people will try to heat them up and resolder some fresh stuff but it is usually futile, you end up mangling the box.

 

I have a 2000 s40. My ABS and brake light are on and my speedometer won't work. The shop I took it to said I needed a new ABS system that was expensive, but not necessary. Told me to download an app to monitor my speed. ?????

 

Go to car-parts.com and look for a yard near you with an ABS unit for a 2000-2004 S40. I paid $60 for mine. If possible get a unit with both the valves as well as the controller. its likely your problem is the controller not the valve body - the controller bolts on to the valve/pump assembly so you can swap that out without opening the brake lines.