90 Blazer slow heat and brake code

Hi all, new to group.
Have a 90 Blazer full size, throttle body 350. Has been slow to develop decent heater output for a long time. I have put in a new radiator
(needed anyway) and thermostat with no appreciable improvement. The temperature guage in the cab quit working at some point too, could be a tie in. Any ideas?
Also the brake light has been flashing a code 19 for quite some time, has decent brakes though, Id just like to know what is up with that?
Charles
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Have you checked to see how well the heater core is flowing? Could be blocked up.
Get some heater hose at a parts store and then get a female water-hose connection from Wal-Mart, or any hardware store. Put the connection on the heater hose and connect that to the heater core with the other hose disconnected from the radiator. Take your "new" heater hose and connect it to a garden hose, and then hit it with the water on full to flush the core out. If you get very little water coming back out the other heater hose, you may need to have the core properly cleaned or maybe even replaced.
I wouldn't think the temp gauge would be tied into the heater problem at all. The sending unit for the gauge should be in the driver's-side head, under the exhaust manifold... IIRC, it's right between cylinders 1 and 3, although it could be 3 and 5 (can't remember). Make sure the connection is good and that the wire hasn't been burned off by exhaust heat. The sending unit is cheap, so you may as well replace it anyway.
Someone will hopefully post a decent method of testing the actual gauge. You could just apply voltage to see if it pegs, but I wouldn't try it until you knew how much it would take without damaging the gauge.
Not sure on the brake light. My K5 is an '86, so it doesn't have any new-fangled computer thingy on there ;-)
~jp
Shelldigger wrote:

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Thanks for the reply Jon,
I had been thinking it could be the heater core, I just didnt want to go there, now with your post I see it may be a necessity. Just didnt wanna! Still dont!
Them new fangled computer thingies are a pain in the rear end! Pun intended.
Charles
Jon R. Pickens wrote:

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Maybe you'll get lucky and blow a bunch of debris out with the water-hose method.
I didn't ever try to change one out. In the C/K trucks it looks pretty accessible, but that doesn't mean it'd be easy. If you do have to remove and/or change it out, let me know how tough it is. I'd just like to know in case I ever need to do it.
~jp
Shelldigger wrote:

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Hey Jon,
Soon as I get some free time to mess with it, Ill try flushing first.
Called the Zone, 26 bucks for the new core. Much cheaper than I thought it would be.
If/when it happens, Ill let ya know! Looks like a lot of interior stuff has to come out. The heater ducting, glovebox, and kicker panel, and the computer. Remind me to disconnect the battery first!
Charles
Jon R. Pickens wrote:

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