ABS and Brake light on startup?

Hi,

It sounds like one of the wheel speed sensors has failed. What I would suggest is to have the can bus scanned. CAN stands for controller area network. Basically, the computers/modules are tied together via a few wires. This type of scan will retrieve codes regardless of the module storing them.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

If that isn't an option, then we need to first confirm the wheel speed sensors are good. Here is a link that explains how to test the sensor.

https://www.2carpros.com/articles/abs-wheel-speed-sensor-test


Let me know if this helps.

Take care,

Joe

Thanks Joe, if it was a wheel speed sensor or something like that wouldn't the ABS and brake lights stay on? The odd thing to me about this is that the ABS and brake light go off as soon as I drive about 100 ft. They won't come back on no matter how much I drive unless I turn the car off, and then the same thing repeats. It's always the same distance of driving, it doesn't matter if I idle for a long time before I drive or if I drive fast or slowly, the lights go off about 100 ft from where I start. Is this normal behavior for a wheel speed sensor failure?

Hi,

It is either a wheel speed sensor that is failing or there is an issue with the output speed sensor on the transmission. If the lights go off and the speedo starts to work, this is my first suspect. I question if the transmission output speed sensor would turn the ABS light on. That's why I'm thinking the wheel speed.

By chance, do you own or know someone that owns a live data scan tool? If so, you could check to see if the sensors are working by watching the individual speed of each wheel. If not, then we would have to check each one with the aforementioned procedure in the link above.

Let me know what I can do to help.

Take care,

Joe

Hey Joe, I connected my scanner and read the ABS module. No faults. Viewed live data: All 4-wheel speeds respond normally as soon as the car starts rolling. Vehicle speed stays at zero for the first ~100 feet of moving, then jumps to match the wheel speeds. If I turn off the ignition, and repeat, I get the same results. The scanner also gives the status of a bunch of ABS related relays and switches. I don't know the system well enough to know what status they should be in, but they seem nominal (?). Again, ABS and brake lights remain on after startup, then turn off after 100 feet of driving at the same time as the speedo starts working. Is this a normal or expected way for the transmission output speed sensor to fail?

Hey again, decided to take the transmission speed sensor out, but it looks like my car does not have one!? I found a guide on where it's supposed to be for the Toyota Matrix version of my Pontiac vibe, but instead of finding the sensor, I found what looks like a "delete" plug covering the hole. Any suggestions for where to look next to solve this issue? Thanks

Hi,

Take a look at the pic below. Are we at the same place? If so, do me a favor. Locate the production date of the vehicle. Maybe if it is an early or late production, something was done differently.

Let me know.

Joe

That does look like the same place to me. Here's a 10 sec video showing where I found the delete cover: https://photos.app.goo.gl/uxpPqcU4PwfRQcvU6

Car build date was 04/04 and the VIN is 5Y2SL62894Z470423

BTW - Really appreciate your help :)

Hi,

I did watch the video and believe you are looking in the correct place. I also looked up the sensor for a 2004 and 2006. Both are the same as what I attached.

So, I did more digging. You do have ABS. That means the sensor signaling the speedo is a wheel speed sensor and not one mounted on the truck. See pic 1.

When testing with a scanner, do all of the sensors start signaling a speed as soon as the vehicle starts moving?

Let me know.

Joe

I set the scanner to show live data from the 4-wheel speed sensors and "vehicle speed" while I started driving. The 4-wheel speed sensors reported similar speeds right away while the vehicle speed stayed at zero until about 100 feet of driving, when it and the speedometer jumped to match the wheel speed sensors. Thanks for finding confirmation that I don't have that sensor!

Hi,

No problem whatsoever. It was driving me nuts because I couldn't make sense of it. LOL I had to look up codes (guessing which would help) to look for variations. That's how I found it.

Since the sensors are sending a signal right away, I suspect there is a connection issue. At least, that is where I would start. The faster the vehicle moves, the higher the voltage to the speedo gets.

Have you checked behind the dash where the connectors attach to the cluster? If you haven't, remove the connectors and inspect the pins for corrosion, damage, or anything that prevents a solid connection.

If that is good, we need to go to the ABS module and PCM. We will cross that bridge when we reach it.

Let me know what you find.

Joe

Great idea, I will check the speedometer connectors. Is there any connector in the engine bay to check besides the big one on the ABS module?

Hi,

I suspect it will be either at the module or the cluster. As far as additional wires are concerned there really aren't any. The harness going to the ABS module includes everything.

Take care and I'll keep my fingers crossed for you.

Joe

Hey Joe,

I pulled the gauges and disconnected and reconnected the wiring connector block several times. I also pulled the wiring connector off the ABS module and hit it with spray contact cleaner and a toothbrush. Unfortunately, it didn't make any difference. Is there anything else you can suggest trying? Thanks

Hi,

I just read through the diagnostics for a speedometer issue. I attached them below for you. The diagnostics are basically what I explained to do. The interesting thing is there is no diagnostic trouble code (P0500).

If there is no code and the speedo doesn't work in conjunction with the speed sensors, they indicate replacing the cluster itself. If you have a chance, recheck to see if there are any codes that showed up.

Let me know your thoughts.

Take care,

Joe

See pics below.

Thanks, no codes. Would a speedometer problem cause the ABS and brake light?

As far as the lights are concerned, I don't see how it could. However, anything is possible. If you can, run through the diagnostics and see if there are any red flags. Maybe we are missing something simple.

Take care and let me know what you find.

Joe

The speedometer diagnostics seem to be basically, drive the car and see what the scan tool says. The scan shows wheels speed sensors to be fine and vehicle speed to be zero for the first 100' of driving, just like the speedo. Unless it's related to the ABS and brake lights staying on for the 1st 100' of driving, I'm not concerned about the speedometer not working for the first 100' of driving. I wouldn't even worry too much about the ABS and brake lights since they always go off and stay off after the first 100' of driving, but I need to ship the car, and they won't accept it like that.

I'm thinking of replacing the ABS module. Does that seem like the next step? They are available used for not too much.

Thanks!

Hi,

If they are inexpensive, it wouldn't hurt to try. I'm going to get in touch with the site owner and see if he has any suggestions. You may see a response from a different person.

Take care,

Joe

Just wanted to follow up. I got a salvage ABS unit and removed the black plastic electronics module from it, despite the sticker warning not to loosen bolts ;). I removed the black plastic electronics module from the ABS unit in my car and installed the salvage one. On startup ABS and brake lights went out as they should. Salvage ABS module scan showed numerous faults. Cleared the faults and test drove the car. Scanned again and no faults found. Seems to be fixed. :)

Thanks again for all your advice

Hi,

Excellent. Great job and thank you for the update. I know this will help others in the future.

Take care and feel free to come back any time in the future. You are always welcome.

Joe