92 Astro Brake and ABS light on

[Vikingmikey]

Hello- I own a 1992 Chevy Astro AWD Extended van, with engine code W. The Brake and ABS light came on at the same time. I check both master cylinder reservoirs and they appeared to have no fluid loss,both are still at same level several weeks later. I have looked for leaks and any sign of fluid on the ground but have found none so far. The brakes seem to still be working fine. Since there is 100,000 miles on these brakes I've purchased new brake shoes,drums,and cylinders for the rear. I also bought new brake pads,calipers,and disks for the front. I have not bought the ABS sensers or brake lines or master cylinder yet and hope I don't have to. I know the brakes pads and shoes have to be low but I hear no grinding or other bad noises when the brakes are applied. Is there some kind of early warning system indicating the brakes are worn down that would cause the lights to come on? I'm a do it yourself mechanic for this van and am looking to replace all these parts myself,that is if I can get the old parts off since I live in Central Wisconsin and have to deal with winter cold and the results of road salt. Just getting the brake lines broke loose without damaging them can be a challenge. My family rides in this van and I need to know they are safe and can stop when the brakes are applied. Thank you for any reply and advise.

[Vikingmikey]

I looked up on how to check for brake/ABS codes at AZ websight. After crossing peg H and A I got the code 61,reset switch. Since I still have not been able to find any problem outright, I cleared the brake/abs codes and the lights went out. I did so by turning on the ignition,crossing prong A and H for two seconds,then uncrossed for two seconds,twice and the codes cleared. I'm still going to replace the parts I bought because they need it but I will see if the lights come on again.