P0720 and P0500

[dantedawg]

BAS/ABS .got this twice today after driving on freeway. suddenly i'm on first gear and won't change gears and i had to stop. i scanned and got p0720 output speed sensor circuit mulfunction and p0500 vehicle speed sensor A mulfunction.

any idea? good thing i have scanner in the car and i can just delete it. this happened about 2000 miles ago. i had the whole thing reset. i was told to turn the steering wheel all the way from left to right a couple of times to reset the ABS/BAS light. i did it today and gone after restarting. i hope it wont cost me a lot to fix it.
hope you guys can help. thanks

* i suggest you guys to get a scanner..this will help you save a lot of time and money. it's very helpful. :)

[sdpartz]

I bought a 97 C230 with a bad speed sensor putting the car in limp mode, resetting the computer is NOT a permanent fix, find out which speed sensor went bad & replace it.

[dantedawg]

Originally posted by sdpartz
I bought a 97 C230 with a bad speed sensor putting the car in limp mode, resetting the computer is NOT a permanent fix, find out which speed sensor went bad & replace it.

sounds good. thats exactly what happened, the car went on a limp mode. any idea how many sensors are related to the BAS/ABS problem? and the cost?

thanks again.

[adamsry]

I believe there are 2 one on the crank and the other on the cams the 2 dictate the ignition timing. This is pretty consistent across all 202's wether 220, 230, 230 Kompressor or 280 at least un-sure on the AMG models though. If you have DOC then possibly 3 crank and both cams intake and exhaust.

[dantedawg]

Originally posted by adamsry
I believe there are 2 one on the crank and the other on the cams the 2 dictate the ignition timing. This is pretty consistent across all 202's wether 220, 230, 230 Kompressor or 280 at least un-sure on the AMG models though. If you have DOC then possibly 3 crank and both cams intake and exhaust.

thanks for the input. this make all sense now. before i had a problem with the engine misfiring P0304. i replaced all ignition coils, spark plug wiring and connectors but i still get the code p0304 once in awhile. now you mentioned the ignition timing, is this somehow connected to the prior problem? regardless i still have to change all sensors related to the problem...im just trying to figure out how much money again is involved repairing.

[adamsry]

Well this is my understanding of the way the whole ignition system in Benzes work. Keep in mind I'm no expert but the Bimmers i owned in the past were similar... moving right along.

When your crank and cam/cams spin there is a micro magnet on them this inturn causes a micro switch to open or close when you use the crank and cam/'s together your able to generate ignition timing this is fed raw to the ecu allong with other emission related goodies O2 MAS etc ets and then based on all these illustrious variables the computer says hey fire cylinder X Y & Z .

Now Mercedes in there engineering feet's decided well what the hell lits just tie this puppy into the trannie to match throttle, power, and kick down ...Wooo this is brilliant gents ... well not so if something is broken. The system is a loop that even includes trannie sensors as well in the popori of confusion so .. should there be a failure well all things are Phucked =)

Hence the reason all kinda diog problems with older 202's and ignition trannie and the such ... you may not realize this but even the AC Compressor is on this same system ... is ant that just peachie keen ... supposedly the clutch dis engages to provide less paralistic drag when you floor it ..

Moving right along to answer your original question ... i seriously doubted that you needed to replace all those parts probably it was the timing that was messed up from the get go.

The switches on the inside are kinda like a spring system when the cam / crank comes in contact with the switch the magnet on the cam / crank causes the metal to open or causes a break in the circuit. over time the open and closing of the switch eventually causes wear.

Keep in mind that ever time the crank / cam turns the switch is opened and then closed it will eventually wears out ... I mean how many time u think you cam has turned just to get you 90k that is allot of turns and on and offs.

With that said replace both switches and save your self a real aggravation with these parts in my opinion if funds available replace them. They are kinda like head lights when one pops typically the others are not far behind.