flashing brake code

[novakin]

Hey, new here.... I have many questions, but I will start with this one.
On the digital dash of my 1990 Gmc Jimmy.. there is a flahing brake light code. Try as I might, I can't find anyone who knows what it mean.
1. the code is three short and one long.
2. Haynes manuals don't have the codes
3. GMC dealer wont tell me unless I pay a ridiculous amount of money to have truck on 'diagnostic machine'
4. brakes are fine, half pads and shoes are there, good looking rotors... line are relativley new.
5. light dissapears for a few weeks if I dissconect battery.
So does anyone recognize this problem?

[Shortbus]

It would help if you told me whether you have four wheel antilock or just rear wheel anti lock. Get back to me with this info and I can better help you.

When you received this code were you jumping term a of the aldl to terminal h of the aldl? Or did the light just start flashing on its own? If not jump these terminall and recount the flashes for me, count the short flashes after the long one. If indeed it is just a code three, for a rear wheel antilock only that means there is an "open dump valve or malfunctioning ECU. Most likely your problem is the dump valve, I have seen many of these go out for the s10 and c/k pickups for these years as these were test models for rear antilock.

I will not get into the four wheel antilock as I doubt yours is so equipped. Hope this helps you.

[novakin]

ok.... i only have rear anti-lock, but i don''t think they work....
i have worse problems right now..... my linkage has fallen apart.....is that possible?

[bowtiebandit]

Linkage to what?

[bigaldover]

Hi everyone.
I jus bought a used 1989 s10 Blazer. When I bought it I did not notice that it had 2 wheel ABS. I am getting 3 short flashes followed by one long, then repeats. I have a GM Code Reader and ther is nothing definitive abot that sequence.
It ay be code 3 (3 short 1 long(termination))
If so the manual says this may be a dump valve or ecu.
The brakes are spongy, so I am hoping for the dump valve.
Where and what is a dump valve ?
the other posibilty is code 4
3 short and 1 long can be a code 4 according to a hanes manual.
Code 4 represents Grounded anti lock valve reset switch circuit.

Any ideas or suggestions are greatly appreciated.

Allan
[email protected]