Rear Squeal + ABS Light On

[OG 91 LC]

Waddup y’all! First thing first. Always grateful for this site and all the amazing knowledgable people and their wisdom. It’s been great to learn so much about these awesome trucks. Let me tell you about my latest quest to make my truck good again.

I don’t drive my truck much. I recently replaced my alternator because I was having staring issues and lights coming on the cluster. My volt light, airbag and ABS lights were on. After alternator swap ABS and airbag lights remained on. I had noticed a squeal coming from my rear passenger side. I figured it was the brake clip letting me know about brake pads. Or so I assume. I have done a decent amount of searching the abs issue. First question for y’all is regarding the squeal coming from the wheel. If it is the brake clip squealing due to brake pads will this cause ABS light to turn on?? Let me start here and then I can move forward with where this take me. Also I took the truck to the Zone to use their obd reader. It came up with nothing even tho ABS light has been coming on. On that note the ABS light comes on 10-15 seconds after driving. Thanks in advance for any input.

 

[baldilocks]

The brake wear warning scratcher's won’t activate an abs fault. I’m assuming the squeal is audible only when brakes are applied?
Not all obd scan tools are capable of abs diagnostics. Perhaps that’s why your excursion to autozone turned up no codes.

 

[OG 91 LC]

I had searched online and had read some info about the absence of enough brake pads causing abs light to turn on.

Yes and no on the sound being audible only when brakes are applied. Sometimes the scratching sound, again I assume is the brake wear warning scratcher, is on while I’m driving without pressing on brakes. I gotta do some more searching and investigate what’s happening on the rear passenger side wheel by taking it off.
Tnx

 

[Malleus]

AI is stupid. Don't listen to it. I've seen brake pads that had paper thin backing plates and no friction material and the ABS was very happily ignoring them.

No scantool will read 80 series ABS diagnostic trouble codes; unless it's a Toyota Tester. You have to use the service manual method. Get one. It's free; it's in the Resources forum, 80 series section. Go there first. Only use the internet when/if you have a question the service manual cannot provide an answer for.

 

[discoverydave]

Good advice above on the FSM approach — that's really the only reliable way to get the actual fault code on these older 80s.

One thing worth checking while you have the wheel off: look closely at the ABS tone ring on the rear axle shaft. On a '96 with that mileage, they're often heavily corroded or the teeth are damaged. The squeal coming from that corner even without brakes applied has me thinking it might not just be the wear indicator — could be a dust shield that's bent inward and dragging lightly on the rotor, or even debris lodged in there. When it's apart, spin the rotor by hand and feel for any catch or roughness.

The ABS sensor itself on the 80 rear is a passive magnetic sensor that reads the tone ring teeth as they spin past. When the teeth are corroded or missing chunks, the signal gets erratic and the ABS module throws a fault. I've had trucks come in where the tone ring looked fine visually but had one bad tooth that you'd only catch if you ran a finger all the way around. Also worth pulling the sensor out and cleaning the tip — they accumulate a lot of iron dust and debris over the years, especially if the wheel bearing has been weeping any grease near there.

 

[OG 91 LC]

As always big tnx for the input. I’ll be checking it out soon and will report back.