97 E320 ABS Light Comes On - PeachParts Mercedes-Benz Forum

s491ja · #1 01-23-2008, 10:38 AM

I am new to the MB family. I just bought a 1997 E320 straight six. It seems to run good, but the ABS light keeps coming on every day. I turn the engine off and on and it goes away. Today it came on and the speedometer quit. I turned off and then on and it began to work again. Can someone give me an idea of what is going on

. Thanks

ja

suginami · #2 01-23-2008, 12:03 PM

A low battery / charging condition?

Arthur Dalton · #3 01-23-2008, 12:53 PM

Check the left/front wheel speed sensor........

s491ja · #4 01-23-2008, 12:59 PM

Thank You suginami! The car does crank right up. I will check the Voltage on the battery and AMPs comming from Alternator. ja

s491ja · #5 01-23-2008, 01:01 PM

Oooo thanks so much Arthur Dalton, can you help me as to how I can check the speed sensor? Thanks ja

s491ja · #6 01-23-2008, 03:49 PM

My wife just called and said the ABS light is on the speedometer is not working and the transmission is not working. Does this tranny have a speed sensor. I will put the computer on it to check for codes.

s491ja · #7 01-23-2008, 06:35 PM

I received a code PO720 "Output Shaft Speed Sensor Circuit". Can this be causing the ABS light to turn on? Where can I find this sensor and is it expensive? Help

Arthur Dalton · #8 01-23-2008, 06:44 PM

<>
Per MB/DOC..

Do a search on "P0720".

s491ja · #9 01-23-2008, 06:55 PM

Thank you so much. Would it be located on the outer top side of the ring gear location like most american built cars? and Is it a only a dealer item. Thanks for saving the day. I was reading another thread where they said it was in the transmission. Thanks again.

Arthur Dalton · #10 01-23-2008, 07:03 PM

Do the search..there are two..one in the trans and the other is at the differential.
Speedo sig should come from tran conductor plate turbine sensor.
I will check.

INFO:
http://www.peachparts.com/shopforum/search.php?searchid=1955544

I would suspect the trans sensor b/c you have a tranny complaint and a speedo problem. The differential speed sensor would be sispect if you had just ABS problem.

s491ja · #11 01-23-2008, 10:41 PM

Unfortunately the link did not work. Will you please re link. Thanks

Arthur Dalton · #12 01-24-2008, 01:12 AM

If the link does not work for you, just use the Search Feature on top of the page and use "P0720".

s491ja · #13 01-24-2008, 12:38 PM

I think I need to give a little history. The previous owner said the ABS light would turn on about once a month, he would turn off the engine and then back on and it would go away. This tranny was rebuilt a year ago and was running shifting great. When I bought last saturday it turned on like every other day. We turned off and on and it would go away. Last Tuesday we had the tires rotated. Discount tire guy says tires are almost to their limit. We did not buy new tires. It was after the rotation of the tires that the ABS light started coming on more often and the next day the speedo started to not work turned off and on and worked again. This followed by the ABS light staying completly on and the check engine light on (code PO720) and the transmission not shifting out of first (i beleive this is the Limp mode).

In reading through some of the forum their is indication that the ABS system can trigger the tranny to go into limp mode, is this true?

If so would it also initiate a PO720 code?

The forum threads also mention that the tires if not in good condition can trigger the ABS system to initiate, is this true or possible?

I also understand from the forum that I need to get the codes cleared in the tranny computer of which only a tranny or stealership can do.

Here is my question, if get new tires, get the codes in tranny cleared and clear the car computer (OBD II) will the car operate correctly?

(again the only thing we did was rotate tires and the issue developed

)

Arthur Dalton · #14 01-24-2008, 03:09 PM

Tire size and pressure must be equal all around..the computer looks at a comparison of the wheel sensors, so..coupled with your noticing the change
after tries rotated and they have wear, I would start there.
First check should be PSI ...

s491ja · #15 01-24-2008, 03:56 PM

Great, I will check pressure and even replace if need be. How do I clear tranny codes?

Also I found this statment on another forum, is this true?

"The ABS part of it is where the speed of all 4 wheels is known, then ABS knows what to do when its needed. The same signal is required by the gearbox to know what gear to be in, when the signal is missing it goes into the limp home mode (2nd)."

Thanks