I purchased GS 2019 few weeks ago, had the brakes worn message on the dash. I found that front brakes are almost done, so I moved with replacing the front brakes as well as the sensors. The message still there, and I found out that the previous owner cut both rear sensors "pre- wires" as well as removed the brakepad sensors, so I literally can't see where the rear sensors now can be connected and ai am trying to find out the right part number for these pre wires. what is driving me to go into this hassle is that the cruise control is not properly functioning, first I can't set it when the speed is over 90 km/h and even on lower speed it keeps getting deactivated and I have to recall the speed.

Is the message of Brakes Worn related to Cruise Control? No errors on the whole PCM except the brakes worn message

 

It's not hard to imagine that GM has some limitations on setting the cruise control if the car believes that there are some braking issues. My memory (sometimes faulty) is that installing new rear pads would give you the parts you need to reconnect the rear brake sensors. Unless you have CCBs, I don't believe that the pads are particularly expensive. Just out of idle curiosity, how many miles on the car?

 

Car got 94,000 KM as mileage, and the brake rotors are Carbon Ceramic. I paid a fortune on the front brakepads

 

In that case, I'd try to find the sensors and wires if available.

 

Those sensors plug into a harness that's on the control arms I believe. @Bill Dearborn knows more about this.

 

I am trying to find that harness, where it is connected. I can't find it at all, appearantly the previous owner did cut it 😀

 

Here are the part numbers for the sensors. I had these saved in my phone from about 4 years ago, so might want to recheck these online.

the plastic tab part inserts into the pad and simply wears away over time until the wire is exposed. Once the wire is exposed, you get the light on your dash. I can’t imagine someone so cheap to spend the ungodly amount of money on the pads, but to simply cut off the wires and stare at the warning all day.

Front 23316707
Rear 23300243

 

Thanks mate, I got the part numbers for the sensors. What I am searching for is the part number for the pre wires (the one that comes from the PCM) to the brake sensor clip

 

Ah, that I can’t help with. However, as mentioned above @Bill Dearborn is your man. He’s a wealth of knowledge on the Z06 and the z07 package specifically, which is on your gs.

 

Don't you just love bone heads that cut wires ***** nilly without ever thinking about consequences? I need to understand your terminology better. The FSM schematic for the Brake Wear Circuit is shown below:

When you reference Pre Wires are you referring to wires such as 1610, 1612, 1613 and 4081 that are shown connecting the sensors?

Bill

 

Correct, for the rear sensors only as the front are ok. What are they connected to? I mean the part number (pre sensors wire) I can search for as I already have the sensors

 

OP I closed the old thread you bumped. Please keep all your discussion here.

 

The wires are part of several harnesses. The FSM isn't clear on which harness they are part of. For instance, in the diagram above you can see connector X174 mentioned twice (Pins 34 and 40). That connector connects the Engine and Transmission Harnesses.








What we can see from the schematic is Wire 1612 goes from Pin 9 of the EBCM mounted on the driver's side in front of the serpentine belt on the engine. There is no indication whether this is just a single white wire dropping from the EBCM to the brake wear sensor connector on the driver's side of the cradle or if it's part of a harness that goes that way. The wire for the left front wheel speed sensor goes from the EBCM to the left front wheel so it seems logical there might be a harness that routes and protects those wires. Then we have wire 1613 traveling across the front cradle to reach the right front wear sensor connector. Is that a single thin wire or is it part of a harness? Now we get to the area we are interested in: the right front brake wear sensor is connected to connector X174 Pin 40 and from that pin to the right rear brake wear sensor through 1611. Connector X174 is located on the lower right side of the engine. As I mentioned before this connector connects two harnesses, the engine harness and the transmission harness there is no indication other than the Pin 40 reference that this wire passes through these two harnesses, there isn't any indicator but the schematic that indicates there may be two wires connected at Pin 40. From the FSM, I surmise there is more than one transmission harness. There may be several serially connected to go the distance from the engine to the transmission/other circuits located at the rear of the car. Then wire 1610 travels across the rear cradle to reach the left rear brake wear sensor. From the left rear brake sensor, wire 4081 travels to connector X174 Pin 34 and from there wire(circuit) 4081 connects Pin 34 to EBCM Pin 23. I doubt you would want to replace the harnesses as they would be a huge PIA to replace. Individual wires may be easier to replace but I doubt it would be easy. I suspect the break in your circuit maybe with the wire that runs from the right rear to the left rear brake wear sensors or in the 4081 circuit that is more than likely inside the harness that goes from the rear of the car to connector X174. If the problem is in a connector it could be due to a pushed pin or a broken wire. To start I would double-check the rear sensors to see if there is continuity between Pins 1 and 2 on each of the sensors, then check the continuity of wire 1610, then check the continuity of circuit 4081 from the left rear to the EBCM pin 23.

As for replacing broken wires, I would rather splice them.

Bill

 

Thanks Bill for the detailed explanation, the issue I am facing is that there is even no wire in both rear brakepad wheels that I can connect the sensors too. Honestly I don't think a transmission wire is the one, I am thinking to take off the cover and try my luck to trace the wires.

Another question please, I couldn't find rear brakepad sensors, instead I found the front ones. Do you think they will fit? I am not sure if there is anything difference apart from the front seems to be longer?

 

I just looked under my 19 base Stingray. The pad sensor wires run parallel and are clipped to the rubber brake hose. Right next to where the rubber hose connects to steel brake line there is also a connector for the sensor wire. Both the wire connector and brake line joint are mounted on a black stamped steel bracket. After the wire connector the harness is wrapped in silver heat reflector. It runs on top of the alum subframe toward the rear of the diff and up each side of the diff

Wires from both calipers run similar paths and go up along the back surface of the diff. A pigtail comes off for each AFM valve. It looks like they join above the diff and go through a 2" grommet into the body of the car. I didn't have much luck getting light to the grommet so I did a green outline showing where it is. I hope the PO just removed the sensor wires at the connectors. If you have to get into the heat shielded harness that will not be fun.

 

I can't thank you enough for this , it is literally what I was looking for. To confirm my understanding, the "connector" and the "harness" in the first image is on both sides?

The connector seems to be 13580874 of a part number?

 

Yes, there is a similar bracket, connector on both sides of the car. BTW 20yrs working on Lexus cars I am not surprised that a brake pad warning cancels the cruise control. I don't have a list but I bet there are probably 5-6 items that cancel cruise. I remember one model would cancel cruise if a brake light bulb burned out. Our Honda Pilot has been getting the 'Snow' drive mode used quite a bit in the last 2 weeks. Being in that mode cancels cruise.

 

Is this the right part number for the connector? 13580874

 

I have no idea about part #s. I just looked under my car to trace the wiring since you were having a hard time finding the end of a cut wire.

 

The base car doesn't have electric brake wear sensors. The only cars that get those sensors have the CCM brakes which only come with the GS, Z06 and ZR1 models. I suspect those pictures are showing the ABS sensors instead.

The connectors for the brake wear sensors are located on the cradle near the Ride Control Suspension Movement sensor. Here is the left-side brake caliper showing the CCM pads, the location of the sensor on the pads and the sensor wire passing through a notch in the caliper body. From there the sensor wire runs alongside the caliper body until it turns and if I remember correctly (my CCM brakes have been in boxes for 9 years) is clipped to the ABS sensor harness until it reaches the cradle where it is connected to the car wiring. The connector is tied down tightly to the cradle so you have to loosen the covering some in order to remove the sensor half of the connector.


Here is a diagram from the FSM showing how the Brake Wear Sensor Harness is routed from the caliper toward the cradle:



If the sensor has been removed from the pad just follow the ABS sensor harness to the cradle and look at the top of the cradle for an empty connector. The rear wear sensor connectors are located further inboard on the cradle than the front connectors. I remember when I changed the stock pads at the track I could access the front wear sensor connectors from the wheel well while I had to crawl under the car to access the rear wear sensor connectors.

Some people may have removed the sensor pill from the brake pad and looped the sensor back along the ABS harness. The system has no idea if the sensor is located on the brake pad. It only knows if the electrical current path is broken. When I went to the AP Racing brakes I just looped my sensors back toward the cradle and made sure they couldn't come loose from the ABS harness.

Bill