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ABS, Traction Control or StabiliTrak light on, speed sensor codes stored. Some 2007-09 GM cars and minivans may illuminate the ABS, Traction Control or StabiliTrak light on the dash and store one of more of the following wheel speed sensor Wheel speed sensors are sender devices used for reading the speed of the vehicle's wheel rotation. It usually consists of a toothed ring and pickup.
C0035, C0036, C0037, C0040, C0041, C0042, C0045, C0046, C0047, C0050, C0051, C0052. GM says lots of modules are being needlessly replaced as a result of the stored code(s), and has come up with a simple three-step diagnosis to help techs more easily nail the more likely culprit - an out-of-whack wheel speed sensor signal. Here's the drill:
With the ignition off, disconnect the harness connector halves at the speed sensor that contributed to the DTC
Now get out your trusty DVOM DVOM Digital Volt-Ohm Meter , set it to the ohms scale and check the resistance across terminals A and B of the pigtail A cable that has an appropriate connector on one end and loose wires on the other. It is designed to patch into an existing line or to terminate the ends of a long run. Contrast with patch cord. harness leading to the sensor. You should see 850 to 1350 ohms on the meter display. If you don't, replace the sensor; it's trash. If the resistance is within this range, try manipulating or bending the pigtail while you watch the meter display. If the resistance goes out of range, you're dealing with an intermittent in the wiring. Replace the wheel speed sensor.
If everything looks good up to this point, check the resistance between each sensor terminal and the steering knuckle. Now reverse the leads and check the resistance once again. Your DVOM should read infinity during both checks. If it doesn't, the speed sensor is shorted; get rid of it!
The final step in the diagnosis is to determine the output voltage from the wheel speed sensor, which is critical to the proper function of the ABS, Traction Control and StabiliTrak systems. To do it, set your DVOM to the AC volts scale, connect the two leads across the sensor terminals and spin the wheel while monitoring the voltage on the meter display. What you want to see is a minimum of 10Om V, with the reading increasing as you speed up the rotation of the wheel. GM doesn't say it, but a more accurate way of checking the output voltage is with a lab scope. Just connect the leads of the scope, set your time and voltage bases, then spin the wheel. You should see a sine wave A continuous, uniform wave with a constant frequency and amplitude. See wavelength.
Sine wave that peaks at 10OmV, with both the amplitude and frequency of the wave increasing as you increase the rotational speed of the wheel.
The following vehicles are prone to the warning light illumination and speed sensor codes noted:
2007-08 Cadillac XLR, DTS models; Chevy Corvettes, Impalas, Uplanders & Uplander EXTs; and Pontiac Grand Prix
Thank you for this post! I've looked all over the internet for info on the "0040" code.
I have a 2005 Pontiac Montana SV6. Occasionally the "Check ABS" and "Check Traction Control" lights would come on. The display (where the mileage is) would also alternate those two error messages. Sometimes after backing out of a parking spot, and putting the van in drive, the traction control would kick in for about two seconds.
I went to Auto Zone and got the new speed sensor. Took me a while to figure out where it was located, but found it plugged into the transmission. You can get to it by removing the right-front wheel. It is on the far back side of the right-front part of the van.
Anyway, when I pulled the old speed sensor out it was covered in black grease. Does anyone know if that is normal???
I put the new sensor in (un-greased) and so-far so-good, but it's only been a couple of hours.
Another hint for anyone else with a similar vehicle......the guy at AutoZone said they don't have a speed sensor for the 3.3 or 3.4 liter Montana's. They only had that part for the 3.5 liter van. You can tell if yours has the 3.5 if the 8th digit in the VIN is the letter "L"
I have intermittent "Service Brake Assist," "Service Brake System," and "Service Traction Control System" warnings. Every morning, and sometimes throughout the day. It happens more and more now, but still goes away. This should be somewhat helpful in determining which bearing/sensor is at fault. Thanks!
I have an update for my situation...
The day after installing the speed sensor the lights came back on.
I did more research and found it to be the right-front speed sensor. However, that sensor is integrated into the hub assembly. I bought a new one at Advance Auto Parts. Unfortunately, the lights immediately came right back on.
I took the van to a local Chevy dealer. They charged $45 to tell me what was wrong with it. Turns out the right-front ABS wire harness is bad. I went ahead and got that part ($100) while I was there and I'm going to install it tonight.
Got the van back from the dealer. Turns out one of the prongs in the EBCM module was loose and one of the wires was chafed around the front strut. The dealer fixed those issues and (I think) it finally resolved my issues.
In response to the intermittent "Service Brake Assist," "Service Brake System," and "Service Traction Control System" warnings.
I have a 2006 Buick Terraza with this issue, and found the problem to be water that gets in to the ABS wire that attachs to the wheelhub assembly. The warning lights did seem to appear after it rained. So the fix was to grease and rewrap the electrical wires with electrical tape and this fixed the problem. If you talk to mechanics this is a common issue with GM vehicles.