I find low voltage faults stored often, it is usually caused by the battery being run down in the past. Erase the faults a see which faults return first, I suspect the solenoid circuit faults will return as these are tested each time you start the vehicle and begin to drive.
My bad sensor caused the “Trac Off” and “Anti Lock” warning lights to come on. Sometimes, very rarely, my regular brake warning light came on by itself. Maybe there is a separate problem I don’t know about.
The auto part store has a ABS relay for my car… Cannot find any documentation on the location of this relay. It does not seem to be in any of the fuse boxes but there appears to be a few in various points under the dash. Anyone know where to find the ABS relay on this vehicle?
Car had been sitting so I put in a new battery to get it going. Do not think it is a battery issue. I think the key to figuring this out is the noise I am hearing at the same time the lights illuminate. For the longest time I thought I was hearing bad shocks rattling on my gravel driveway. I feel it in the steering wheel too. I think the gears in the motor pack or hydraulic modulator must be making that sound. I just need someone to ride in the engine compartment while I drive to help narrow the source. Any volunteers?
I have a used motor pack ordered that will be here Tuesday. I hope that somehow bad motors can draw enough current to cause the low voltage. I do not know if that is the case but I am really hoping. Do not want to start tearing apart the wiring harness to find the bad spot. I already did that last week with a short in the interior light circuit.
If you are curious watch youtube video -
Buick - ABS Overview (1991)
skip to 10:29 to see a detailed description of my ABS system… or at lease it looks like that one.
ABS systems often make a noise like that in normal operation when they detect one of the wheels has locked up. Maybe that’s all that is happening. Or one of the wheel sensors is acting up, making the ABS think a wheel has locked up, when it actually hasn’t.
Any luck figuring this out? I’ve had the same issue for a long time and have given up until I saw your post. No one else has ever posted about the noise and slight jiggle in the steering wheel when the lights come on. I saw one post where someone claimed that air had gotten in the ABS pump and since I had recently replaced the pads, I thought this was plausible. Others have said that the ABS module should be replaced, but I don’t want to spend $100 on a guess.
Did you ever figure this out?
Yes I did. So I had been thinking it was the gears in the ABS motor pack. I purchased a used motor pack off ebay without realizing that I was getting an entire ABS assembly. I then tried to remove just the motor pack from the ABS in the car and decided that it was not possible without removing the entire ABS assembly. Since I had the ebay one handy I decided to swap it. The assembly would best be installed using a code tool that has an option to cycle the brake fluid through it. I don’t have one so after watching YouTube I learned that I could get around using the tool by bench bleeding the assembly, installing, bleeding ?front? brakes, driving 3 miles an hour and then bleeding the back brakes. I think that was the process, please don’t rely on my directions. Anyway, YouTube said to get some nipples from the auto part store and screw them into the brake line ports so that tubes could be attached for the bleeding process. I promptly ruined the entire assembly by using nipples with incorrect threads. I then purchased two $8 bench bleeding kits from ebay that had plastic nipples - nice as they will never damage the threads even if you use the wrong ones. It took two kits to get enough plastic nipples for this ABS system. I then ordered another ABS assembly from eBay. The new ABS assembly was damaged in shipping so I got it for free - broken plug on solenoid. I was able to replace the busted solenoid by cannibalizing one of the other ABS assemblies. Anyway, I bench bled this last ABS assembly using the ebay kit and it worked great. I went to remove the ABS from the car using the proper tubing wrench but they were so tight that I rounded a few of them off. I ended up having to use vice grips to turn the brake line fasteners. I got the new assembly installed in about 15 minutes without having to take anything else off the car. I tightened the rounded brake line fasteners with the vice grips. It kinda looks like crap if you look closely because of the damage the vice grips did but all the issues were resolved. The lights and vibration are all gone.
What a hassle! But, good that you got it to go away. I’ll investigate this option and may be looking over eBay for some parts 
I’ve had a buttload of little issues over the last year or so and it’s driving me crazy. The rear speakers come on and go off at seemingly random times, the air blend door under the drivers side decided to stop working even though the actuator is OK and I can see it move if I disconnect it, two of the windows now don’t move, …. It seems like every issue I can find with this model is happening to mine!
I’m thinking there may be a short somewhere or something. If this was a project car, it would be fun, but I drive this thing everyday to work.
Thanks for the reply.
jeff