ok. got very low resistance on that. I also checked the wire that is the pink wire from the vcm to the abs pump, both with the ignition on and running, and i get no power from that wire on the 3 wire plug that goes into the abs pump. I do otherwise get a reading from the red wire, the constant, which is fine. And all the grounds look fine. Maybe my vcm/ecu took a dump? I looked at the wiring diagram for the abs system and for the abs and brake light indicator they both run off of the vcm, besides the ebrake running to the brake light.the line circled in yellow is the abs power wire that wasnt gettin any juice. I know its hard to see but it says abs voltage on the vcm side.

 

today i also tried hooking up another ecu/vcm and the abs light still does nothing, and the brake light went off. But as soon as i started driving it, the brake light came back on and has been on ever since.

 

Had some problems with my 94. After reading the book out of shear frustration it turned out to be one of the brake switches although not the one I thought it would be. You might check them. It's easy and sure doesn't cost much. I know a bad one will turn on the brake light. Mine was turning on the ABS light at 15 mph and would go off when I slowed to below 15 mph. These KH units do funny things.

 

ok. would ur abs light come on with the ignition on before u start it??

 

Yes. Everything acted normal and then accelerate to 15 mph and I got a light. Slow down to below and light went out. You have a brake light that comes on and no ABS light at all? I'm just passing along about my experience with the switch. It wasn't any good and was $16.00. Why that fixed it I have no idea. But it sure was cheaper than an ABS module. I don't know about the setup in a Blazer newer than 94. Don't know if they are the same or not. The brake kight came on in my 84 Jimmy and it ended up being the combination valve (proportioning valve). This little jewel actually has three functions built into it. It also cintrols the brake light as does the ABS module.

 

yea i believe the abs in mine is slightly different because its got the same abs pump, the pressure sensor in the proportining block but its controlled by the ecu/vcm because its the 1st year obd2. Yea the abs light does absolutely nothin. If you look at the three wire connector to the abs pump, with a red wire, pink wire, and black wire, if you check the voltage from the pink and black, do u get 12v out of that when the ignition is on? Because on the wiring diagram, it shows the pink wire is the abs voltage feed. I only get about .05v out of that wire with it running. Im thinkin its supposed to be 12v when the ignition is on. do u have that on that truck?

 

According to my wiring diagram for the "Brake Warning Sustem" yes, through the Pnk/Blk wire. It comes from the IGN/GAU fuse (20 amp) and them to the instrument cluster (I have the digital cluster). All warning lights and switcges turn on by going to ground if malfunctuining (Tan/Wht wiring). What the manual says about the "Brake" light under "Circuit Operation" is it lights with a hydraulic problem (or the parking brake on) and the ABS light lights if there is an electrical or electronic problem. For example if there is unequal pressire between the two hydraulic systems, the "Brake" light will light.
My ABS module is powered by a Pnk/Wht wire coming off the IGN/GAU fuse. I have rhe OBD1 system and when the switch was bad it lit the ABS light and I read the code from the ABS light flashes not the SES light. Makes sense though. The port is "H" on the ALDL. Not the same for yours. Have you had any codes?

 

yea i actually figured it out. believe it or not with the obd2, there was a code for a abs bulb. so that explains why the brake light was on. changed the abs bulb in the dash and theyve both been off ever since.. wierd. isnt it?

 

Yep. I guess the ABS light would have been on but the bulb was toast. Ha-ha. Actually the factory book says that the "Brake" light is kind of like a backup to the "ABS" light.

 

yea now it all makes sense.