Service brake system

[Danzigman]

So I have been dealing with issues that came up in rapid succession. I had a front ABS sensor that went out. Today I swapped that out with the correct AC Delco part. While changing this one out I noticed that the pads needed to be changed so I plan on doing that next weekend. While changing this sensor out I compressed the caliper pistons to ease the reinstall. When I got in the truck I started it and started pumping the brakes to return the piston to the correct position. While I was doing this the service brake system soon light and then the whole service traction system light came on. I have ordered the new pads, my question is once I replace the pads will this light turn off or is there something that has to be done to reset it? I cleared the abs codes with my scanner to clear the wheel speed sensor code but these lights remained.

 

[Fless]

Will your scanner read the code that's triggering the light?

 

[Danzigman]

No, the only code it had was the abs sensor that I replaced.

 

[ivin74]

Could be the ABS module under the truck.

 

[Danzigman]

I hope not as this sounds like a pain in the ass and i don’t work on electronics. Also i don’t see how compressing the brake caliper would cause this all the sudden.

 

[Danzigman]

I did find this tech bulletin that was refered to on another site for this issue. #03-05-25-007C

It says if the speed sensor mounting surface isn’t throughly cleaned it can cause a gap issue. I am going to give this a try when I replace the pads.

 

[MassHoe04]

I did find this tech bulletin that was refered to on another site for this issue. #03-05-25-007C

It says if the speed sensor mounting surface isn’t throughly cleaned it can cause a gap issue. I am going to give this a try when I replace the pads.

That is a possibility. Crusty surface can create enough of a gap to make the sensor go too far out of range.

Some sensors ship with or need shims to make sure they are not grinding on the tone ring. There is also a possibility that an old shim is stuck on the hub. If the new one has a shim on it, two shims could be a problem. Sensor would be too far away from the tone ring.
Make sure you check the surface when you scrub it with a wire brush. If there is an old shim stuck on the hub, you can flick it off with a flat screwdriver, metal scraper or even a knife blade.

If there is no old shim stuck on the hub, the new sensor does have a new shim on it and still not working... You can try the new sensor without the shim it came with. Just be sure to look and feel to make sure the sensor is not grinding on the tone ring. Just slip it in without bolting it in. Turn the hub by hand gently. If you can see the sensor move the slightest bit or you can feel the sensor vibrate with your finger touching the top of the sensor as you rotate the hub... Don't just bolt it in there and drive on it! If it contacts the tone ring without the shim, you definitely need a shim on there to provide clearance.

I did my ABS sensor and found there was, in fact, an old shim still stuck to the hub. I tried no shim and could actually feel the sensor making contact. I added the new shim and was good. For a while...

ABS codes and lights and chimes were pinging on the highway. I ignored those signs, not knowing any better. Eventually the hub completely fell apart.

Keep in mind this: Sometimes, what looks like a simple ABS speed sensor code can be the leading clue that a hub is about to fail. Excess play in the hub can get sloppy enough where the ABS sensors have a hard time picking up the tone ring. Maybe not your issue at all. Just file this cautionary message for the future. Anytime you get an ABS speed sensor code/light/chimes... Be sure to carefully inspect the hubs for excess play.

 

[Danzigman]

Good advice! How much play should the sensor have? The original sensor had separated in the hole, I had to pull the outer plastic on the part in the hub out separately.

 

[Danzigman]

After doing some additional research I believe it is the hub. I can get the Moog hub here by Friday so I plan to get this one, the AC Delco will not arrive until Monday...

 

[MassHoe04]

Good advice! How much play should the sensor have? The original sensor had separated in the hole, I had to pull the outer plastic on the part in the hub out separately.

Sorry for the delay in reply... Close as possible, but not touching. Depending on the sensor, it may or may not need a shim.

Your new hub most likely comes with a new sensor pre-installed. If so, there should be no compatibility issues and be a plug-n-play install.

 

[Danzigman]

So I i stalled the new hub today. The old one definitely needed replacing as you could here the bearings rattling. I also installed the new pads. The old pads were just a hair away from the warning tabs. The brake feel is lot better. The Moog hub had the speed sensor installed so I didnt have to mess with that.. The lights and messages however are still there. I assume they would reset themselves if the problem was fixed. I checked and there is still no ABS error code. I tried to reset the codes with my scanner anyway but no change… Now more research I guess. I really thought the new hub would correct the problems as this set of lights only appeared after the previous sensor change.

 

[MassHoe04]

Some scanners will read but not clear ABS or ABS speed sensor codes.
If your scanner could clear the codes and there was still some issue, then the lights and messages would be off then come back on after clearing.

Do you know if the codes were actually cleared?

If the scanner is not able to clear them, then the stored codes might take a little driving to go away. They would still be stored, but not active anymore.

Is what you see active codes or just codes that have not cleared?

 

[Danzigman]

When I scanned for codes there weren’t any. There was originally a right front wheel speed sensor circuit malfunction code (C0040). I cleared that code last weekend when I installed the new sensor. I drove the truck approximately 100 miles last week then swapped the hub. I then checked for any abs code and there was not one present. I drove the truck maybe 10 miles yesterday to see it the light would clear but it did not. I wonder if that was not enough. The light came one last weekend as soon as I hit the brake pedal to pump up the brakes after compressing the brake caliper. It comes on as soon as you start the truck it never went away. No new code ever appeared. When I scan it, it shows no code currently.

 

[Danzigman]

So i have been thinking about this. Could there be air in the line/abs controller from compressing the brake caliper pistons somehow? The passenger side pads installed without issue. When i installed the drivers side pads last weekend, i compressed the caliper pistons and it caused fluid to flower from the master cylinder fill cap. I thought this was odd but thought since the caliper pistons were extended that it may have caused me to add more fluid at some point.

 

[ivin74]

So i have been thinking about this. Could there be air in the line/abs controller from compressing the brake caliper pistons somehow? The passenger side pads installed without issue. When i installed the drivers side pads last weekend, i compressed the caliper pistons and it caused fluid to flower from the master cylinder fill cap. I thought this was odd but thought since the caliper pistons were extended that it may have caused me to add more fluid at some point.

That's normal. When the pads wear out the oil gets low and if you Indeed added oil at one point installing the new pads would have caused the oil to over fill the reservoir.

 

[Doubeleive]

When I scanned for codes there weren’t any. There was originally a right front wheel speed sensor circuit malfunction code (C0040). I cleared that code last weekend when I installed the new sensor. I drove the truck approximately 100 miles last week then swapped the hub. I then checked for any abs code and there was not one present. I drove the truck maybe 10 miles yesterday to see it the light would clear but it did not. I wonder if that was not enough. The light came one last weekend as soon as I hit the brake pedal to pump up the brakes after compressing the brake caliper. It comes on as soon as you start the truck it never went away. No new code ever appeared. When I scan it, it shows no code currently.

please clarify if there is only "service brakes" message or ABS light on AND "service brakes" message.
no abs light denotes a different condition.
1. brake fluid level sensor bad
2. prop valve stuck
even a tech2 would only show" service brake ill yes/no" in the readout for this condition
if there is no ABS light on then try unplugging the brake fluid sensor
the service brakes message should go away, this would confirm the 2 possibilities above
if then testing the brake fluid sensor operation or replacing the brake fluid sensor does not correct the issue try doing several emergency stops over a few days, preferably on gravel, this can possibly un-stick the prop valve and correct the issue.
my 03 prop valve got stuck doing the same thing, in my case I had just finished doing the brakes and I had forgot to pump the brake pedal and drove off then realizing I had no brakes I stomped on the pedal, this caused a immediate "service brakes" condition.
after digging around the internet quit a bit I found the above information to be accurate and confirmed with my tech2, I did a number of emergency stops over a couple days and on the 3rd day when I started it up the message was gone
now i make sure to slowly give it pedal after doing brakes until they are pumped back up.

 

[Danzigman]

please clarify if there is only "service brakes" message or ABS light on AND "service brakes" message.
no abs light denotes a different condition.
1. brake fluid level sensor bad
2. prop valve stuck
even a tech2 would only show" service brake ill yes/no" in the readout for this condition
if there is no ABS light on then try unplugging the brake fluid sensor
the service brakes message should go away, this would confirm the 2 possibilities above
if then testing the brake fluid sensor operation or replacing the brake fluid sensor does not correct the issue try doing several emergency stops over a few days, preferably on gravel, this can possibly un-stick the prop valve and correct the issue.
my 03 prop valve got stuck doing the same thing, in my case I had just finished doing the brakes and I had forgot to pump the brake pedal and drove off then realizing I had no brakes I stomped on the pedal, this caused a immediate "service brakes" condition.
after digging around the internet quit a bit I found the above information to be accurate and confirmed with my tech2, I did a number of emergency stops over a couple days and on the 3rd day when I started it up the message was gone
now i make sure to slowly give it pedal after doing brakes until they are pumped back up.

The abs light is on as well. You described the exact scenario that happened with me. I forgot to pump the brakes before putting it in gear. So i should try some emergency stops?

 

[Doubeleive]

The abs light is on as well. You described the exact scenario that happened with me. I forgot to pump the brakes before putting it in gear. So i should try some emergency stops?

abs light means there is a different problem then, you need to pull the code with a scanner that can read abs, most of the cheapy ones and bluetooth ones will not read abs codes.
you need one that specifically states it can read abs, because abs and obd are different, so is srs (airbag).
if you bled the brakes at any point it's possible there could be air trapped in the abs pump

 

[Danzigman]

I have not bled the brakes. My new XTool scanner doesnt show any abs codes for some reason. I will try it again this weekend. In the meantime, the brakes function without issue and the pedal feels fine.

 

[Danzigman]

Thinking about this, my old scanner (an Innova scanner with abs reader) didn't read a code either after I cleared the original speed sensor. The light doesn’t come o. Until I start the truck. I wonder if I need to scan with the truck running?