2000 S70 GLT SE Volvo

I can drive it for miles after the codes have been cleared. The abs/ brake light comes on dimly.... Like it would do if the engine dies, but doesn't. The engine light comes on too. It always says something in regards to speed control.... But I have put a good one in and still get the engine light stuff. I have gotten codes that don't even show up on the devices they use.... Expensive ones. My mechanic checked out all the codes that were in and every one said their was a "communication problem". The question I would like answered is this.... Can a faulty speed control and/ or abs sensor cause this car to run bad. It doesn't make sense that a abs sensor or even a speed sensor would cause this car to run like crap. These lights have come on and rough running even before I move! When all lights have been cleared and its running smooth.... I can drive sometimes for miles before all of this stuff happens too. Sometimes I can just turn it on.... Let it run and these lights and rough running occurs before I even move. As I said... I have put a good speed sensor in already..... But the same stuff happens. When it running fine.... I'll be driving just fine.....then The abs/ brake lights come on... Dimly. 5 secounds later the speed ometer and tachometer go straight to zero..... Temp and fuel gage keep working. Everything beside this certain problem works. After the Gage's go to zero as I said.... It will eventually start running bad. My mechanic feels its a bad computer. He says his diagnostic tool keeps putting communication as a problem on all the codes. ( he doesn't have the cheap one like auto shack. If you can get these computer things or at least the one that works these problems showing up.... Its a chance I will take. When this car runs without all this stuff.... It runs great! Engine sounds great/ transmission feels great. But as soon as those lights start coming on..... I know it's gonna act up. Sometimes I can pull over and turn it off... Turn it back on and all is well. Then the lights start coming on and the next thing... It running bad. I saw a change in this routine when I sprayed electric cleaner on the ECM. I don't know what else to say. Don't forget.... Sometimes all of this can happen before I even take the car out of park. - yippy kiyay!.

 

Hi Adam, welcome to the forum.

You typed a lot of words but didn't say much. How do you know "a good one" was put in? I assume you are talking about the ABS module? Since that is the light that is coming on, and you have cluster issues, you should start there.

Also, if your mechanic can't read the codes from the OBD-II, go somewhere else and see if they can read codes for you. These cars are know for having bad ETM's but I would start at the ABS since those are the lights you see.