ABS/ Brake light Question

[MassHoe04]

UPDATE....I pulled the front driver caliper where I had my issue during the brake job. I had my son get in and push the brake pedal so I could see if both pistons moved freely without leaking fluid. We did not get any fluid to leak, but what I did find is one of the pistons moved outward as it should, but the other does not. I'm going to assume this is not correct, and that pistons should move together. I'm also assuming this may be causing my lights because maybe its sensing a lack of pressure in one of the 4 corners?

Does anyone feel like I'm on the right track here?

The one that did not push out is probably hanging. That is what my rear calipers were doing and they locked up.

You don't want that...
Really should be considering caliper replacement.

You could rebuild DIY, but for the money differential and time to do it, you can get new ones with a warranty.

As far as the lights and sensing low pressure on one corner... I personally don't think so.
Cylinders would fill until pads hit rotors and pressure would hold steady until the brakes are released.

But the hanging caliper is going to need attention to have brakes function properly. Hanging caliper on the front can be a real safety issue, because your steering is involved.

 

[Blk00ss]

The one that did not push out is probably hanging. You don't want that...
Really should be considering caliper replacement.

You could rebuild DIY, but for the money differential and time to do it, you can get new ones with a warranty.

I agree, but do you know if this could cause our ABS/ Brake lights to be on? I'm gonna replace it today, but I'm wondering does the system have the intelligence to recognize this, and throw lights?

 

[Fless]

It's possible if that wheel isn't braking at the same rate as the others. This would cause that wheel to continue to turn faster or slower than the others and the ABS system may sense that if it's extreme enough.

Good that you're fixing the caliper, but I'd be calling auto parts places to ask if they have a scanner that can read ABS codes, and get that code.

 

[Blk00ss]

It's possible if that wheel isn't braking at the same rate as the others. This would cause that wheel to continue to turn faster than the others and the ABS system may sense that if it's extreme enough.

Good that you're fixing the caliper, but I'd be calling auto parts places to ask if they have a scanner that can read ABS codes, and get that code.

I've done that. I have Oreillys and Autozone near by. Both places scanned and only picked up my evap code. Not really interested in using a stealership to do it. Plus, I want it done today if possible.

 

[Doubeleive]

I agree, but do you know if this could cause our ABS/ Brake lights to be on? I'm gonna replace it today, but I'm wondering does the system have the intelligence to recognize this, and throw lights?

I don't think so, if this was a 2021+ maybe as they have new types of brake sensors
the brake codes MUST read with a ABS capable scanner and when the abs/brake light is on/active, you probably will not get a historical brake code depending on the issue as I explained previously.
if you need to go buy a scanner, use it as needed and then return it later, no harm no foul put it on a cc

 

[OR VietVet]

Agree with @MassHoe04 here. That stuck piston is not good and is obvious problem and hopefully is THE problem. Don't try to rebuild, unless you have done before but I would bet that the parts house has reman calipers before rebuild kits. Again, I would use OE or AC Delco calipers. If the light goes out after, great. If not, at least you fixed a KNOWN problem.

 

[MassHoe04]

Harbor Freight has one with a sale coupon for only $79.

ZR8s OBD2 Code Reader with Live Data

Amazing deals on this Zr8S Live Data Obd2 Code Reader at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Worth every penny to keep until the day you might get a fancier bi0-directional reader or maybe even a Tech 2 scanner.

For $79 you can save a lot of time and gas running to the parts stores to have them do it for you...

I bought the one up from that until I got my Tech 2 clone. Now I keep the Zurich in the console, just in case I want to scan a code on the road and not wait until I get home from somewhere.

 

[purp]

Our '05 with 175K on it has started doing this. Brakes work great, no change when this light comes on. Just did a front/ rear brakes a few weeks ago. I can disconnect battery and get the light to turn off for a few days, but then it comes right back. I went ahead and cleaned the two ground connections under driver side door. We don't live up north and our truck is quite clean, but I cleaned them up anyway. Light still comes on. Can this be a wheel sensor? Or is this definitely EBCM related? I don't solder (I suck at it), so I'd probably consider a new or reman one. But, do they require a reflash?

I'll just vent for a second...these vehicles now days run forever. Maybe thats part of the reason vehicles are so expensive these days. But as I've stated for many years...its not the mechanical stuff that craps out. Its everything around it.

View attachment 384305

I've been dealing with a similar issue on my '03 Yukon. Started off with replacing the EBCM and the light was still on. Had another tech look at it, wound up being an electrical issue. Some wires got damaged under the engine bay fuse panel. Hopefully this helps a bit.

 

[Blk00ss]

I've been dealing with a similar issue on my '03 Yukon. Started off with replacing the EBCM and the light was still on. Had another tech look at it, wound up being an electrical issue. Some wires got damaged under the engine bay fuse panel. Hopefully this helps a bit.

You mean the main fuse block under the hood? How did they get damaged? Just curious

 

[MassHoe04]

You mean the main fuse block under the hood? How did they get damaged? Just curious

Hungry mice, clumsy mechanics are common causes for damaged wires.

Corrosion inside the fuse box connections can also cause a lot of electrical headaches.
Mouse urine and droppings are really corrosive, if they ever got in the fuse box to set up house...

Lift the box out and give a good inspection inside, top and bottom. See if anything jumps out at you as a possible problem with terminals, connectors or damaged wires.