Brake warning light flashing intermittently (bad hub or speed sensor?)

Capote

Gold Supporter
#1
Hey people, had a strange occurrence tonight while driving home. I stopped on the way back from work at Mcdonalds tonight. And while I was sitting in the drive-thru my Brake Light flashed and dinged for less than a second out of nowhere. I was very surprised and cautious. Then about 2 or 3min later it happened again for a split second. Then one more time about another 3 or 4min later. Drove down the road and once again it popped up, but this time with the ABS light also flashing for a split second (ABS light didn't flash the previous 3 times). Nothing happens for about 5 minutes, then again the Brake Light flashes for a split second with a quick ding. Probably less than a second. The remainder of the drive home this didn't occur again. No CEL on the dash. When I scanned for codes on Dash Command, the Chassis code for the Vehicle Speed Sensor shows up. I've had that code for months though and never had this flashing Brake Light issue before. Could this be a sign of a bad wheel hub or vehicle speed sensor. I replaced the VSS once already after I swapped in my 2nd transmission rebuild a while back. I have a feeling it might be a wheel hub and it's tripping the Brake Light and also tripped an ABS warning quickly the one time it happened tonight. I can check my hubs this weekend when I have time for wheel play. I know i'd have to get a Timken brand hub if I don't want them crapping out sooner rather than later.
 

Tiggerr

Gold Supporter
#2
I've never heard of a hub tripping a brake light.....
Could your e-brake "on" switch be off a bit and the lever moving a bit cause it?
How's your pedal? Could your master cylinder be about to puke? Maybe not putting out quite the pressure it should and tripping the sensor?
 

Capote

Gold Supporter
#3
I've never heard of a hub tripping a brake light.....
Could your e-brake "on" switch be off a bit and the lever moving a bit cause it?
How's your pedal? Could your master cylinder be about to puke? Maybe not putting out quite the pressure it should and tripping the sensor?
My brakes are crap, shuddering as I'm braking, no matter what speed. I have to really brake earlier than normal (brake fluid is at the full level). Brake pedal isn't spongy, but braking isn't abrupt. The rotors seem warped or the pads aren't worn evenly maybe? The pads are more than likely why braking isn't biting as hard, its to the point where they squeak at very low speed braking or at a crawl. So they're needing to be replaced anyway.

Now about the brake light, perhaps the optical sensor that reads the brake fluid level is acting up somehow? Idk
 
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Tiggerr

Gold Supporter
#4
My brakes are crap, shuddering as I'm braking, no matter what speed. I have to really brake earlier than normal (brake fluid is at the full level). Brake pedal isn't spongy, but braking isn't abrupt. The rotors seem warped or the pads aren't worn evenly maybe? The pads are more than likely why braking isn't biting as hard, its to the point where they squeak at very low speed braking or at a crawl. So they're needing to be replaced anyway.

Now about the brake light, perhaps the optical sensor that reads the brake fluid level is acting up somehow? Idk
Could be.... didn't know these had an external sensor like that...
kinda along the lines of what I was think about your e-brake too .. I'm sure there's switch somewhere that lights the brake light when e-brake is on...maybe a bad contact there or switch loose and not staying properly aligned...

Kind of an odd issue... not one I've ever had except with a failing master cylinder...
 

littleblazer

Well-Known Member
#5
The hub and other sensors should only act up while stopping not while stopped. To me that's something else. Maybe the brake switch failing? It's weird.
 
#6
If you're getting a code for speed sensor, that's the one out of the tranny/TC. If that one fails, it should trip the ABS light. I'd be checking that. The hubs can also trip the ABS but it would be a different code and the usual issue is ABS activation while slowing down for no reason.

If it was flashing/intermittent, I'd be checking the wiring to that sensor.
 

Capote

Gold Supporter
#7
ABS light or brake light never came on today while driving to work.
Only thing I did different yesterday was pulling up into McDonalds in 3rd and then staying in 3rd while idling. I never use 3rd unless I was actually in busy stop and go driving in towns, or behind some really slow moron going less than 50mph and I can't pass. Could someone being in 3rd instead of D while sitting there in the drive-thru have somehow caused some sort of hiccup with something? Seems really unlikely though as how though. But as I said, no issues today as of yet.
 

Capote

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#9

Capote

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#10
Once I started my truck tonight both the ABS and Brake light go off with chimes for 4 seconds then they both dissapear. I'm really puzzled here. No codes other than the hidden chassis code for the Vehicle Speed Sensor I've had forever.
Truck is braking no different than any other day.
 
#11
Do you read the codes right away without shutting off the truck? Those codes should stay in memory as long as you keep the ignition on.
 

Sir ffeJ

Well-Known Member
#12
I can't remember, but isn't there something to do with dirt getting in a sensor some where? I'll see if I can find what I think a read.
 

Capote

Gold Supporter
#13
Do you read the codes right away without shutting off the truck? Those codes should stay in memory as long as you keep the ignition on.
Yup that's exactly what I did, no codes.
I can't remember, but isn't there something to do with dirt getting in a sensor some where? I'll see if I can find what I think a read.
Would appreciate that man.

-Checked to see if my pads are extremely worn out, they're getting low, but not to the point where it's in risk of crumbling to pieces. Heard that can trip the ABS and Brake Light too because of the pistons having to be out more than normal, causing the brake fluid in the reservoir to be lower than it's supposed to be. The fluid is at the full mark. And it terms of it being related to the parking brake, where would the sensor be in relation to that? I do use it every night as my truck sits on a slight incline. Have pulled on it a little too hard on a few occasions.

-Once again the they both popped up once I started the truck on two occasions. And again no issues with braking or ABS shudder.
 
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#14
IIRC, the switch for the parking brake is in the lever itself. But that wouldn't trip the ABS light though.
 

Capote

Gold Supporter
#15
IIRC, the switch for the parking brake is in the lever itself. But that wouldn't trip the ABS light though.
I guess i'm just gonna have to unplug both ABS cables, clean the connections and hook them back up and see if anything persists.
 

Mounce

Silver Supporter
#16
Doesn't the brake and abs light come on with a bad ignition switch? I know the brake light comes on and dings and the ac blower cuts out but can't remember if the abs light comes on as well. First thing I thought of when topic was originally posted but held out to see if it was easily resolved sooner.
 

Capote

Gold Supporter
#17
Doesn't the brake and abs light come on with a bad ignition switch? I know the brake light comes on and dings and the ac blower cuts out but can't remember if the abs light comes on as well. First thing I thought of when topic was originally posted but held out to see if it was easily resolved sooner.
I can't quite remember all the details, but I have replaced the OEM one a few years back. Don't remember what the symptoms were though.
 

Capote

Gold Supporter
#19
Could be worth a shot.
ABS & Brake light both appeared with dinging for a few seconds then disappeared once I started my truck after work. After doing more research on TV, it seems a bad ground located on the frame just in front of the driver's seat area can be a cause. I've gotta start out easy and small here. I'll check that as well as look into replacing the ignition switch again. Sad that I may have to do that being that it was an AC Delco one I used 2yrs ago?
 

Tiggerr

Gold Supporter
#20
ABS & Brake light both appeared with dinging for a few seconds then disappeared once I started my truck after work. After doing more research on TV, it seems a bad ground located on the frame just in front of the driver's seat area can be a cause. I've gotta start out easy and small here. I'll check that as well as look into replacing the ignition switch again. Sad that I may have to do that being that it was an AC Delco one I used 2yrs ago?
Don't forget about the ground on the right side of the console towards the front too...
Can't hurt to check them all
 

Capote

Gold Supporter
#21
Don't forget about the ground on the right side of the console towards the front too...
Can't hurt to check them all
Ahh yes, that crazy trip-everything-out one behind the carpet partition.