Hi everybody! New user.... been lurking here a bit lately looking for helpful information to make a few repairs on a 99 Blazer I just bought. As you can tell from my user name I am a little frustrated at the moment, hence Nutty 99 Blazer. I just don't get this thing....

Anyway, a little background... I recently purchased this 1999 2 door Blazer w/ Vortec 4.3 V6 (ain't that motor pretty much the case with 'em all?) So, I bought it with the understanding that it had a bad heater core and possibly the fuel pump was on it's last leg because the gas gauge was quite erratic. So, I proceed to purchase a new heater core. I removed the dash per the directions listed on another web site (not sure if I'm specifically allowed to name it here, but it's pretty much equal to a factory repair manual). I get the new heater core installed and re-install the cluster and dash assembly. I reconnected the battery and she fired right up. I proceeded to bleed the air out of the cooling system and top her up with Dex. So I'm thinking, "It's all gravy from here!"... NOT! The next day I go to fire her up and NADA... NOTHING. Just some bouncy gauges and the radio would work momentarily if I turned the key in the ACC position. So, I take the battery out (practically new-man. in 02/09) and take it to AutoZone to have them check it. I'm thinking I may have a bad cell because I couldn't even jump start this mother. AutoZone verifies it's "good" and just needs a charge. So I leave it with them overnight to charge it. I pick up the battery the next day and install it in the Blazer. She fires right up! I turn it off and proceed to restart again. NADA! NOTHING! Same as before. This time the gauges bounce all over the place again and my speedo gets stuck on "100" while sitting still (thank BTW, found the solution to that problem on this site!). So, I think to myself, "Why don't ya have a look at the battery cable terminals to see if they are gunked up?" Sure enough, the positive cable is all gunked up. I spray it with contact cleaner, sand it down with some emery, and run some steel wool over it until she's nice and clean. I hook everything back up and she fires right up! YAHOO!..... or so I thought. I drove that think like 40 miles with several stops. Each time she started right up with no problems so I'm thinking, "Hell, it was just a dirty cable connector causing my problems". NOPE! WRONG! Blazer sits overnight. I jump in her this morning to take off to a doc appointment. NO START! NOTHING! This time ALL the warning lights on the dash just go bezerk flashing like they are hazard lights. No start, no courtesy lights, no dome lights, and the light under the hood didn't even work (BTW, does that light run through the ignition switch?). I open the big fuse block under the hood and tap the 50 amp fuse labled "INT BAT" and notice the light under the hood come on.... I'm thinking something is amiss here at the fuse block???? Well, the underhood light stayed on for about 3 seconds and went right back out. I tried tapping it again, no luck. I even swapped another 50 amp fuse out thinking maybe it's a faulty fuse (highly unlikely as either they are good or bad, not in-between).

So anyway, I'm sitting here with this nice Blazer in the drive. I just replaced the friggin' heater core and now I can't even start and drive the *(&$(#*@& thing! ARGHHH!!!

I am suspicious that either I have:

A) A bad connection/ground under the hood that I must have disturbed while doing the heater core replacement.

OR

B) I have a bad ignition switch that decided to take a dump on me at this critical juncture.

OR

C) This d@mn thing is just possessed!

Sorry for the long-winded post but would anyone care to chime in if they have a clue. I sure the hell don't seem to have one!

Thank you in advance and have a wonderful day! Cheers!

P.S. Yes, I have used the "search" feature extensively here before making the decision to post my question. Maybe I haven't typed in the right key words or ????

 

A little update with additional information.... hopefully this will help me solve this mystery.

The battery is an Autolite Part No. 75-84 with 630 CCA. I measured the voltage with a multimeter and it read 12.5 volts. I'm pretty sure it should be a lot closer to 14.5 volts, eh? I cleaned the positive battery lead that connects to the fuse block under the hood. I also unplugged a couple of plugs under that block and cleaned them too. I did see some noticeable corrosion on one of those terminals on the plug. I also pulled all the big fuses and polished them clean with steel wool. Anyway, this battery is not that old and I noticed when I first started working under the hood (for heater core fix) that there was this plug that was not plugged in to anything on the side where the fuse block is. I was curious as to where it belonged. I finally determined it was a plug that goes to the Brake Proportioning/Combination Valve so I plugged it back in figuring someone must have worked on this vehicle at one time and just spaced out plugging it back in.

Question: Is it possible this could be a source of "parasitic battery drain"? I have read a little on the subject on this site and I guess that could explain why that was unplugged but then again this Blazer biz is new to me!

Anyway, I also cleaned the ground points I could find under the hood in the engine compartment. I hooked the battery back up and it was enough to get the underhood light back on but I wasn't about to try and start it without a jump. So I used my Silverado to jumpstart it. I compared battery voltages on my Silverado; a healthy 14.45 volts as compared to the sickly 12.5 volts on the Blazer. So I am starting to lead to a parasitic battery drain. I did replace the stock stereo with an aftermarket Pioneer head unit while I had the dash apart. I'm wondering if this too could be enough to zap the battery overnight? Thoughts? Ideas?

THanks!

 

Are you measuring the voltage of the battery with the engine running? If so, it should be around 14.5V. If the engine is off, 12.5V isn't outside the realm of acceptable.

Acceptable amperage draw on the battery once all of the components have done to their low power state is around 35mA. Much more than that and you'll have an issue with the battery maintaining charge over somewhat long periods of time.

The warning lights flashing on and off are a classic sign of an ignition switch failure. But since you were in the dash doing the heater core replacement, there is the possibility of leaving a ground disconnected or somehow compromised that could affect the operation of the dash as well as BCM which could impact starting.

 

Yes, you are absolutely right on the battery... I don't know what the hell I was thinking. Do you ever get a brain fart when you have been wrenching on a particular vehicle for a week trying to fix one of those nasty elusive "gremlins"? Sometimes ya just gotta take a step back for a day or two and take a deep breath, but I digress.....

As for the ignition switch I am still holding that thought as a strong suspect. Perhaps digging around in all of that fun dashboard stuff just tweaked something enough to push it over the cliff? However, I was thinking back through my heater core replacement and exactly everything I did. The site I was using called for pulling back the plastic blower motor/AC housing under the hood as far as possible for some reason that escapes me at the moment.... I'd have to go back and look that up. Anyway, the point I am getting to here is that there is a huge braided ground cable on that side of the engine bay that was definitely disturbed in the process of me pulling back this blower motor/AC housing. This is one of the ground cables that terminates on the passenger side firewall and the other end terminates....ummm... somewhere in the bottomless pit of a place I can't see too well. Anyway, I decided to go ahead and thoroughly clean both ground cables that terminate to the firewall. Interestingly enough, that seems to have solved the problem.... well, I hope! I cleaned those ground cable ring terminals with a file until they were nice and shiny and made sure the terminals on the firewall were clean to promote good conductivity. I hooked the battery back up and she fired right up! I took her for a test drive and it ran like a champ. The real test was when it sat overnight. That's when it has been typically crapping out... after sitting overnight i.e. that's why I started to suspect "parasitic drain". So anyway, I go out this morning and stick in the key and she fires right up with no problem! I drove her to work and it sat in the lot during my 8 hr. shift and started up again at the end of the day! So I'm hoping and praying that perhaps I just had a gummed up ground. I guess time will tell. But I am definitely keeping that ignition switch on the suspect list. This thing has 110K on it and from what I've read so far it seems to be a common failure at this mileage.

As a side note, can you tell me where the big braided ground cable on the passenger side firewall terminates down in the engine bay? There's an awful lot of stuff crammed in that small space. Does it terminate to the engine block, frame, or ???? I ask because I'd like to find the other end and check its condition.

Thanks and your feedback is greatly appreciated!

 

Good deal and good luck! The large braided ground strap goes to the back of the passenger cylinder head. I believe that the other on at the firewall goes to the PCM. If that were to loose its ground, it could definitely cause some odd things to happen.