Hey there. I was trying to read trouble codes for my brake light being on but pin "H" on the ALDL has no wire going to it. My question is do the wires go to the ALDL via the ECM? Or does anyone have a diagram of the ALDL? Any help or suggestions is appreciated. Thank you in advance.

 

Page 2 4th post down I posted a pic of the ALDL with each wire labeled by letter hope it helps.

 

What year truck do you have? If it's the 1984 S-10 in your post unless you have a California model you don't even have a computer. Also you won't have anything to Pin H because that's for ABS and I don't think they had it then. If you have a computer and want to read engine codes it's Pin A jumped to Pin B (the two far right ones in the upper row). Do you have ABS? I have a 1984 Jimmy and it's not even listed as an option in the owner's manual. I don't think you're going to find what you're looking for. There are a couple of things that will turn on the "Brake" light. Jow brake pressure caused by inadequate fluid supply, a sticky parking brake mechanism (under your left kick panel and dash not releasing all the way, leaky combination valve (some call them proportioning valves), the brake going too far to the floor for whatever reason - big time leak, etc. Believe me I own one and have had just about all the above over the years. If you naster cylinder is full or almost full I would check for the parking brake not fully releasing first. You can stick your hand under the dash a wiggle the mechanism and see if that turns the light off. Then I would start hunting for leaks. When's the last time you changed the brake hoses? Then calipers and rear wheel cylinders and then (hopefully not) the combination valve. They aren't cheap. I had one a seal on the end cap was leaking and you can't buy ANY parts for them. Keep us posted.

 

Okay so I did not know it did not have ABS. Sorry for that. I know how to do the Check Engine light. The truck is California emissions and I have not done the calipers or rear wheel cylinders and I believe the brake hoses are all original. I went out and checked the parking brake and it seems to release all the way. Gave it a wiggle, nothin. I did notice that it looks like there should be a wire coming off of part of the parking brake but it was not there. Anyone know what this is? I can snap a pic if it will help.

 

What part did you give a wiggle to? There is a spring loaded piece that your brake release handle attaches to. That's what I'm talking about. When you release the parking brake it should slam back against a little rubber stopper inside the cab under the dash. Check to make sure it hits. A little out of adjustment or sticking and it'll light the "Brake" light. Check your combo valve to see if the connector is still attached (should be in the middle of the valve with a white rubber cover over it. If this is loose or disconnected it'll light the light. Then you get to go leak chasing. Start with the M/C and progress to the combo valve, LF caliper, RF caliper and then to the LR and RR wheel cylinders. These lights don't just go on for no reason. By the way the combo valve sits right under the M/C.
PS 25 years on the hoses is way too long. They're cheap and have a tendency to collapse inside. Hope this helps. I have actually never ran into a carbed California smog equipped Blazer or truck. They have a Rochester E2SE carb instead of a 2SE carb like mine. I have a factory Service Manual on an 84 if you need any info.

 

Alright I will let you know if I find anything. I gotta get a few bucks together to replace the lines. I also need to buy a new bulb for the dash because it went out yesterday. I pulled the instrument cluster and the bulb is burnt out. I made sure the combo valve was on and it is on there good. I gave the whole parking brake a wiggle and I will check to make sure it releases all the way to the rubber stop. It doesn't seem to be leaking anywhere, I checked all hoses and the master cylinder is still full from when I did my front pads awhile ago. Thanks for the help will let you know how it goes. If I have any questions I will be sure to take advantage of your manual.

 

So now it leads to an electrical problem since all the dash lights quit working. Accept for when I turn the key to go and start it the seatbelt lights comes on and then goes off. I hate electrical problems. Will have to see if I can get it into the shop. Maybe they can tell me why my hazard flasher fell out also.

 

Checked my fuses and my 20A Courtesy fuse was blown. I think it happen the other day. There was a wire behind the dash that is not plugged into anything. Looks like a light for the ashtray. Replaced it now my dash lights are operational. Now to get some more bulbs and sockets for the dash. Then I will start with the brake light problem again.

 

You know, electrical problems really aren't that difficult. It's the mindset that you have.

 

Yeah you are probably right. Just more time consuming than hard I suppose.