QuestionQUESTION: Hi Wayne,
I was using an OBD2 Car reader on my 95 Chevy Venture and cleared the code out of the system by accident. The problem(ABS) is still there but I can't get the code because the unit is in flashing condition/mode. The manual has instructed me to do a Drive Cycle for my car. Can you tell me the proper way to perform this procedure? The OBD manual does not say how this is performed and what i found on the Net is general(might not be for my vehicle. Is this Drive Cycle done with the OBD linked to the system? Anything that you can tell me would be very helpful.
Thanks much,
Tim
ANSWER: Hey,
What kind of code reader are you using? Depending on what kind of reader you are using it may not pull ABS codes or clear them. An ABS code does not need to be cleared to put the light out. When you turn the key on a self test is done and if all is good the light will go out. The code will be stored in memory but the drive cycle is just a matter of taking it up to a road speed greater than 30kph and cruising for 2 minutes. Global OBD2 scanners will not give you ABS, SRS, BCM or TCM codes.
w
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QUESTION: Hi Wayne,
The scanner is made by Innova Electronics Corp and you're right, I don't see a thing in the manual about ABS codes. The unit belongs to a friend and he informed me that it could be used for ABS codes. I don't think he ever used the thing to be honest. Anyway, the reason why I'm fooling with this tool is because our ABS light has been on for about a month. Sometimes it goes out, but it's on more than off. Last summer I fixed/replaced the ABS sensor on my 2001 Nissan after having my neighbor bring his scanner over to pull the ABS code(he works for Nissan). Anyway, as with my Nissan I was hoping to pull a code to point towards what sensor is acting up and then using my multi meter to confirm the problem. I enjoy trouble shooting these things and figured I'd get my research done and fix it once the weather warms. Outside of having the wrong scanner, do you feel I'm taking the right steps? Also, can you a recommend a scanner for this type of work? Thanks again.
Tim
AnswerHey,
I have a selection of scan tools and values at my shop that I have purchased over the years such as a SnapOn Modis, MT2500, OTC 4000E, Vedis, Genysis, and a Tech2. that can be used on GM vehicles. They range in price from 2500-15000 brand new with all of the options, cables and software. Here is an auction on ebay for a 4000e (http://cgi.ebay.com/ebaymotors/OTC-4000E-Auto-Diagnostic-Scanner_W0QQcmdZViewIte
Its is going for 143 bucks and would have OBD2, ABS and airbag for your vehicle.
Once way you can test ABS sensors with a DVOM is to disconnect the sensor and test resistance of all 4 and compare the readings. If you have a sensor that is way out of spec (lets say 9.4mohms when the rest are 2.5k) you know which one to replace. If you rotate the wheel on the AC scale on a meter with max hold option you will see what the maximum amplitude of the signal waveform will be. Make sure to use a steady rotation on all 4 wheels. I made an arbor for my cordless drill with a poly inline skate wheel so I can rotate all 4 wheels with the drill pressed up against the tire. It is very consistent and convenient. Consistency of the tire rotation speed is very important as amplitude increases with wheel speed on a magnetic reluctance sensor. This is a great way to test for weak sensors. If you rlight is coming on all the time it is probably an open sensor that you will find on your DVOM. Make sure to check the ABS harnesses very closely for rubbing on front end components and check the plugs for green corrosions.
Wayne
