Abs code

[Blueburban90]

I have a 1990 suburban that the brake light is blinking. It blinks it blinks 10 times then stays solid for about a second. This is while in park idling. Any help would be appreciated. Also if I depress the e brake pedal it stays solid when released it goes back to blinking

 

[Wes Harden]

Is the lamp red or yellow ? Also do you know which abs system your truck came with ? RWAL or 4WAL

 

[Blueburban90]

Is the lamp red or yellow ? Also do you know which abs system your truck came with ? RWAL or 4WAL

I have no clue if it's rwal or 4wal. I'm going to guess 4wal since it is a v1500 4x4 suburban. The lamp coming on is red

 

[Wes Harden]

The red lamp is is indicative of the hydraulic system.
Please look for leaks check the brske fluid level in the master cylinder.

Since I forgot yesterday Welcome to CK5 @Blueburban90

 

[Blueburban90]

Brakes and fluid level are spot on. No leaks in the system. Thank you for the welcome

 

[Wes Harden]

OK, are the brakes hoses old or unknown age ? Factory or aftermarket lift hoses?
Let figure out type of abs, is there a Squarish block with 5 or 6 brake pipes, on an inner fender, or under the truck. This would be 4wal.
Rwal would have module near the master a few wires and 2 brake pipes

 

[Blueburban90]

I will look at all that when I get home. Driving it back to Montana from AZ right now. All brake hoses lines etc are original from 1990 to my knowledge

 

[Wes Harden]

Is quite common for brake hoses that age to have issues.
1 they can swell and balloon, not allowing pressure to appstore the piston. You can actually feel them swell by hand, when holding and another presses the pedal.
2 internally the hoses crack and can form a flap that acts as a check valve.
How does the truck stop? Do you have a firm high pedal?
If you needed to slam on the brakes how confident are you the truck will stop quickly?

 

[Blueburban90]

Brakes work as they should. The light has been on for a yr or so

 

[Wes Harden]

The 1990-91 4wal module had 2 pressure switches that would get stuck and were not serviceable. When you are able to perform some maintenance, flush the old brake fluid, with fresh brake fluid try to activate the abs, by panic stopping, a few times, then bleed the system. This may unstick the pressure switches.
I will look through my GM books I vaguely remember this system.