Brake problem won't go away- need help
 

[EDIT- problem solved! See last post]

This brake problem is becoming frustrating. This on an a 2005 C6, Z51 (if that even matters). Stock brakes, aftermarket wheels with stock TPMS (programmed with TPMS tool no issues according to DIC), Callaway coilovers. Stock engine tune except for O2 codes turned off via HP Tuners, running long tube headers with cats.

Here's the condensed version:
ABS/Active Handling/Traction control lights all come on at same time.

Pull codes, C0040, right front wheel sensor (I think that's the right letter- it's definitely 0040 and definitely a brake system fault code)

Send to local Chevy dealer, tech finds intermittent dropout on right front wheel sensor while driving- recommends replace right front wheel sensor and auxiliary harness (the piece that goes from the wheel sensor to the main harness).

I purchase two SKF wheel bearings (the ZR-1 type bearings) and thus, two brand new ABS sensors. Install today, went for a drive. No problems. Install the second bearing, go for a longer drive- same three lights come on again. :toetap:

WTF do I do know? I spent $260 on diagnosis at the dealer, another $800 for wheel bearings (I was told that it is best to replace the wheel bearings in pairs). Still have the same issue, exact same code.

[update]
I replaced the aux wire harness for the right front, still has the issue, but now it doesn't happen like clockwork- it is intermittent and really only happens now on hard acceleration. Doesn't matter if I drive with traction off or on. I did notice in city driving that even with traction turned off, it seems to not give me full power in first gear- is that torque management?

I'm now suspecting the EBCM going bad, which is a common problem on C5s. I'm wondering how much different the C5 EBCM is compared to the C6 version- both are Delphi, both use the same basic system and same wheel sensors.

I could turn off torque management via HP Tuners.

Any advice on how to proceed? Thanks in advance!

What year is your C6???:confused2:

I looked in your profile but there's no info in there.

Bob :flag:

Very interested in how this develops, I've dealt with very similar frustrating abs issues on a different type of vehicle.

Could you tell me the logic in changing out both wheel bearings? I understand the one throwing the code.

Thanks and good luck

Sounds like you need to re-check what you did when connecting the second wheel bearing. Also spin the bearing and see if you can get a voltage reading from it. You may have gotten a bearing with a bad sensor.

Here is the diagnostic procedure for that set of codes.
DTC C0035-C0050
Diagnostic Instructions
DTC C0035 00 : Left Front Wheel Speed Sensor Circuit
DTC C0035 0F : Left Front Wheel Speed Sensor Circuit Erratic Signal
DTC C0035 18 : Left Front Wheel Speed Sensor Circuit Signal Amplitude Less Than Minimum
DTC C0040 00 : Right Front Wheel Speed Sensor Circuit
DTC C0040 0F : Right Front Wheel Speed Sensor Circuit Erratic Signal
DTC C0040 18 : Right Front Wheel Speed Sensor Circuit Signal Amplitude Less Than Minimum
DTC C0045 00 : Left Rear Wheel Speed Sensor Circuit
DTC C0045 0F : Left Rear Wheel Speed Sensor Circuit Erratic Signal
DTC C0045 18 : Left Rear Wheel Speed Sensor Circuit Signal Amplitude Less Than Minimum
DTC C0050 00 : Right Rear Wheel Speed Sensor Circuit
DTC C0050 0F : Right Rear Wheel Speed Sensor Circuit Erratic Signal
DTC C0050 18 : Right Rear Wheel Speed Sensor Circuit Signal Amplitude Less Than Minimum
Diagnostic Fault Information
Circuit ========== Short to Ground = Open/High Resistance = Short to Voltage Signal Performance
Left Front Wheel Speed Sensor Signal = C0035 00 = C0035 00 ===== C0035 00 == C0035 0F, C0035 18
Left Front Wheel Speed Sensor Low Reference = C0035 00 =C0035 00 = C0035 00 = C0035 0F, C0035 18
Left Rear Wheel Speed Sensor Signal = C0045 00 = C0045 00 = C0045 00 = C0045 0F, C0045 18
Left Rear Wheel Speed Sensor Low Reference = C0045 00 = C0045 00 = C0045 00 = C0045 0F, C0045 18
Right Front Wheel Speed Sensor Signal = C0040 00 = C0040 00 = C0040 00 = C0040 0F, C0040 18
Right Front Wheel Speed Sensor Low Reference = C0040 00 = C0040 00 = C0040 00 = C0040 0F, C0040 18
Right Rear Wheel Speed Sensor Signal = C0050 00 = C0050 00 = C0050 00 = C0050 0F, C0050 18
Right Rear Wheel Speed Sensor Low Reference = C0050 00 = C0050 00 = C0050 00 = C0050 0F, C0050 18
Circuit/System Description

As the wheel spins, the wheel speed sensor produces an alternating current (AC) signal. The electronic brake control module (EBCM) uses the frequency of the AC signal to calculate the wheel speed.
Conditions for Running the DTC

C0035-C0050 18
• The ignition is ON.
• Ignition voltage is greater than 8 volts.
• The brake pedal is not pressed.
• No other wheel speed circuit DTCs are set.
• At least two other wheel speeds are not 0 km/h.
C0035-C0050 0F
• The ignition is ON.
• Ignition voltage is greater than 8 volts.
• The brake pedal is not pressed.
• A DTC is not set for the other wheel speed circuit on the same axle.
C0035-C0050 00
• The ignition is ON.
• Ignition voltage is greater than 8 volts.
Conditions for Setting the DTC
C0035-C0050 18
The code is set when the following conditions exist:
• One wheel speed is 0 km/h.
• The remaining wheel speeds are greater than 8 km/h (5 mph).
• The difference between the remaining wheel speeds is less than 11 km/h (7 mph) from each sensor.
C0035-C0050 0F
The code is set when both of the following conditions exist:
• The EBCM detects a change in wheel speed that exceeds 20 km/h (12 mph) between two 10 millisecond wheel speed samples.
• The condition occurs 3 times in 200 milliseconds.
C0035-C0050 00
The code is set when either of the following conditions exist:
• An open or a short to ground is detected on the wheel speed sensor signal circuit by the EBCM.
• A short to voltage is detected on the wheel speed sensor signal circuit by the EBCM.
Conditions for Clearing the DTC
• A current DTC clears when the diagnostic runs and passes.
• A history DTC clears after 100 consecutive ignition cycles, if no failures are reported by this diagnostic.
Action Taken When the DTC Sets
If equipped, the following actions occur:
• The EBCM disables the antilock brake system (ABS) and the traction control system (TCS) for the duration of the ignition cycle.
• The ABS indicator turns ON.
• The traction control off indicator turns ON.
• If the other wheel speed sensor on the same axle sets an additional DTC, the EBCM disables the dynamic rear proportioning (DRP) for the duration of the ignition cycle.
• When the EBCM disables DRP, the red brake warning indicator turns ON.
Diagnostic Aids
C0035-C0050 18
Under the following conditions, 2 wheel speed sensors input are 0 and DTCs are set:

• The 2 suspect wheel speeds equal zero for 6 seconds.
• The other wheel speeds are greater than 16 km/h (10 mph).
• The other wheel speeds are within 11 km/h (7 mph) of each other.

Diagnose each wheel speed sensor individually.
C0035-C0050 18, 0F, 00
If the customer comments that the ABS indicator is ON only during moist environmental conditions: rain, snow, vehicle wash, etc., inspect the wheel speed sensor wiring for signs of water intrusion. If the DTC is not current, clear all DTCs and simulate the effects of water intrusion by using the following procedure:
1. Spray the suspected area with a 5 percent saltwater solution. To create a 5 percent saltwater solution, add 10 g of salt to 200 ml of water (2 teaspoons of salt to 8 fl oz of water).
2. Test drive the vehicle over various road surfaces: bumps, turns, etc., above 40 km/h (25 mph) for at least 30 seconds.
3. If the DTC returns, replace the suspected wheel speed sensor or repair the wheel speed sensor wiring.
4. Rinse the area thoroughly when completed.
Circuit/System Verification
Observe the scan tool Wheel Speed Sensor parameter. The reading should be the same speed on all sensors when driving in a straight line at a speed greater than 20 km/h (13 mph).
Circuit/System Testing
Ignition OFF, disconnect the harness connector at the EBCM.
1. Ignition ON, test for less than 1 volt between the 12-volt reference circuit terminal of the appropriate sensor listed below and ground.
• LF Sensor circuit terminal 21
• RF Sensor circuit terminal 18
• LR Sensor circuit terminal 33
• RR Sensor circuit terminal 19
⇒ If greater than the specified range, test the low reference circuit for a short to voltage.
2. Test for less than 1 volt between the signal circuit terminal of the appropriate sensor listed below and ground.
• LF Sensor circuit terminal 34
• RF Sensor circuit terminal 6
• LR Sensor circuit terminal 20
• RR Sensor circuit terminal 31
If greater than the specified range, test the signal circuit for a short to voltage.
3. Ignition OFF, test for infinite resistance between the 12- volt reference terminal of the appropriate sensor circuit listed below and ground.
• LF Sensor circuit terminal 21
• RF Sensor circuit terminal 18
• LR Sensor circuit terminal 33
• RR Sensor circuit terminal 19
If less than the specified value, test the 12-volt reference circuit for a short to ground.
4. Test for infinite resistance between the following signal circuit terminal of the appropriate sensor circuit listed below and ground.
• LF Sensor circuit terminal 34
• RF Sensor circuit terminal 6
• LR Sensor circuit terminal 20
• RR Sensor circuit terminal 31
If less than the specified value, test the signal circuit for a short to ground.
5. Ignition OFF, disconnect the harness connector at the appropriate WSS.
6. Test for less than 2 ohms between the appropriate 12-volt reference circuit terminals listed below.
• LF Sensor circuit terminal 21 at the EBCM harness connector, and terminal 1 at the WSS harness connector
• RF Sensor circuit terminal 18 at the EBCM harness connector, and terminal 1 at the WSS harness connector
• LR Sensor circuit terminal 33 at the EBCM harness connector, and terminal 1 at the WSS harness connector
• RR Sensor circuit terminal 19 at the EBCM harness connector, and terminal 1 at the WSS harness connector
If greater than the specified range, test the 12-volt reference circuit for an open or high resistance.
7. Test for less than 2 ohms between the appropriate signal circuit terminals listed below.
• LF Sensor circuit terminal 34 at the EBCM harness connector, and terminal 2 at the WSS harness connector
• RF Sensor circuit terminal 6 at the EBCM harness connector, and terminal 2 at the WSS harness connector
• LR Sensor circuit terminal 20 at the EBCM harness connector, and terminal 2 at the WSS harness connector
• RR Sensor circuit terminal 31 at the EBCM harness connector, and terminal 2 at the WSS harness connector
If greater than the specified range, test the signal circuit for an open or high resistance.
8. If all circuits test normal, replace the appropriate wheel speed sensor. If the DTC resets replace the EBCM.

Bill

This is a long shot, but do you have stainless steel brake lines? Sometimes those do funny things to ABS/wheel sensors.

not sure if bill dearborn's procedure is in the service manual, but it does look comprehensive.

Some C-5s had auxillary harness issues. I'd check the connectors, clean and apply dielectric grease.

Sorry, it's a 2005 C6

Thanks for the comprehensive message, Bill!

The weird thing was that I did the passenger front sensor first and it had no issues. Then I did the driver front sensor next. It was after I did the driver front that I had an issue with the passenger front throwing a code. Does that even make sense?

I'm guessing that I'll need a Tech2 to measure wheel speeds.

There is no calibration procedure needed when you replace an ABS sensor, is there?

I have stock brakes, lines, pads, calipers, rotors, etc. Only thing different now is that I'm using SKF hubs.

Phoenix performance told me that if I was going to replace one standard bearing with the ZR-1 type bearing, that I should do both on that axle, because the ZR-1 bearing spins more freely and may contribute to giving differing wheel speed outputs and also may affect braking from side to side. Since they are a very well-regarded Corvette racing shop, I trust Joe's advice and heeded it.

Sorry as well!!

Initially I read that you were getting ZR1 hubs for your car, and I was concerned that if you had a pre-2009 C6 that the ZR1 hubs won't work - in 2009 they changed over from a Delphi to a Bosch ABS, and the wheel speed sensors aren't compatible. The spline count is different as well, but that only applies to the rear wheels.

I re-read your original post to see that you were getting the SKF hubs with the ZR1 type bearings. I know SKF makes those hubs with the Delphi compatible speed sensors for a C5 and C6 up through 2008, and I guess that's what you got!!:thumbs:

No idea why installation of the left one would affect the right one that was working fine before that!?!?:confused2:

No calibration is necessary after installing a new hub.

Bob :flag:

The problem was originally the passenger front wheel sensor. After I did that side, I test drove the car, no fault codes lit. So I thought all was good. Then I did the driver side, test drove again. That's when the problem resurfaced, this time with the brand new hub.

Don't assume you installed the second hub correctly. All it takes is somebody coming up and talking to you at the wrong time and you can mess it up. Been there and done that before.

Check the connector to see if everything is making contact. Also check the hub output with a DVM to see it produces a voltage when you spin it by hand.

The procedure I posted is from the Service Manual.

Bill

I understand what you're saying, but how does messing up the driver's side hub cause the passenger side one to throw a code?

It was really, really easy putting this stuff back together- it's like Chevy planned on making hub replacement an easy job.

I surely can't answer your last question but in the world of car computer electronics, it may have taken awhile for the passenger wheel to throw a code. Or maybe something is just slightly different left to right side of car hubs that you changed. Sounds like bill is saying go back over it slowly and make sure everything's aOK. You also don't get much better advice than phoenix perf.

or could it be it's not what was diagnosed? just guessing....tell us how it turns out.:cheers:

Replacing the bearings in pairs only applies to high mileage cars that assume they wore evenly and over time. If one fails premarutely, there is zero reason to replace them both. Replacing only one does nothing to affect the life of the other.

This silly old timer's myth was started back when wheel bearings were 20 bucks on your dad's impala station wagon. It was believed that when one failed the other wouldnt be far behind. Since they were cheap, you didnt have to keep track of which was replaced when you started hearing a howl from the front end and trying to figure out which was causing the noise. If you changed both, it saved you a future break down. If you only changed one, you stood the chance of possibly guessing wrong which was failing and causing the noise....hence you do both.

At 400 bucks you would have to be an idiot to tell a guy to change them as a matter of course on a low mileage car. If you get a code that says XYZ right sensor on these cars, you change the one that cuased the code, especially when you're guessing as to the cuase of the issue you're having.

I guess thats the problem with 60 year old tech guys at the local stealership. They all persist with telling you what their dad told them before a car had a computer that told you what you needed to know.

The problem with electrical problems is that they can be anywhere in the circuit. That means double checking any connection in the system. If there is a loose fitting pin/socket vibration could be causing the drop outs.

Thanks, Spinmonster. Technically, I wasn't guessing- I paid $260 for the diagnosis that the one sensor was bad, based on Tech2 live readouts showing intermittent dropouts on that wheel sensor.

Now I'm back to square one- I'm thinking about a couple things- 1. take the car back to the dealership and asking the service manager about the diagnosis being wrong; 2. taking the car to Phoenix and have them work on it at a lower rate; 3. buying better diagnostic tools and doing it myself (might be cheaper in the long run).

I don't feel that bad about the wheel bearings only because I know that they go bad and my plan is to take my car to the track with PCA or some other groups (road racing, not drag). I've eliminated one of the weaknesses in these cars with the bearings.

I'll definitely post an update once I find out what is going on.

Maybe that's why the dealer also recommended replacing the auxiliary harness to the wheel sensor?

I'm going to order that on Monday or Tuesday, depending on if they're open on the holiday. That way, if the dealer says I didn't do all of the repairs they diagnosed, they can't say that.