C0268 ABS Code Chevy Avalanche

Röb Ambrösius · December 20, 2015

I have a 2005 Chevy Avalanche that the ABS light has been on for quite some time now. Today I took the positive battery cable off and ohm'd it out to the positive connection of the ABS pump and got infinite ohms. is this supposed to be open? I am assuming that the pump module should be supplied voltage all of the time and the module turns the pump on and off. Any thoughts?

Doug_Scott · December 22, 2015

If I am reading this correctly, you are checking with the key in the off position. Instead of using an ohm meter, use a volt meter with the battery connected and the key on. Using an ohm meter the way you are is not really the way to test it.

Röb Ambrösius · December 22, 2015

I was ohm'ing out from the battery cable (positive) to the end up of the positive abs pump cable. I didn't think about key. I just want to see if these wires are corroded.

tbarn · December 23, 2015

Check the 60A abs fuse in the underhood fuse box. On a functioning vehicle, you should have continuity from the disconnected batt cable to the abs module conn 1 terminal B red wire. Not how I would test it though. Just test for voltage at that terminal. Also check the ground on the frame. Front left body mount area .

Doug_Scott · December 23, 2015

To properly check for voltage drop across a connection you just connect a voltmeter (on 2volt scale) on either side of the connection. On the 12volt part of the automotive electrical system it is generally acceptable to see 0.1v on a connection, but 0.0v is preferred(obviously). With computers and sensors operating at 5volts, acceptable voltage drop is pretty much 0.0v or in the hundredths of a volt range (0.01volt). Keep in mind that the voltage drop is due to resistance. Resistance can be due to anything from a corroded connection to a light bulb(or any other load in the system).

Ground circuits are usually where you will find the largest voltage drops. This is simply due to most not even checking/maintaining ground circuits because they figure on the ground there is no power, so connection does not really impact anything. The opposite is true. Remember that when checking voltage drop, the electrical system must be completely connected. NOTE: Do not test volt drop using ohm meter.

What I used to do to check for something killing the battery overnight was to disconnect the ground cable from battery, and then taking a test light and connecting one end to negative battery post, and the other end to the terminal of the disconnected cable. If the light lights up, then there is enough of a drain on the battery to kill it overnight.