Is there anything I need to know about reviving/starting this '03 Trailblazer 4WD LT that's been sitting for 4 years with a dead battery? Do any of the computers need to be reprogrammed or recalibrated after the battery has been disconnected for that long? Thanks for any info...

 

Gasoline is likely shot unless you used a fuel conditioner. I don't believe you'll have to re-calibrate the ECM, but after 4 years your motor oil needs to be changed out. 2 years is the longest it can go, driven or not.

 

If you have a significant amount of gasoline in the tank, add 2 or 3 cans of Berryman B-12 to it and then add at ;east 5 gallons of fresh gasoline. You might want to get a can of ether to make starting the engine a little easier.

Once it is running I would not be surprised if the Check Engine comes on. Be sure and read (and write down) all the codes before you attempt to erase any codes. Most of the codes might vanish once you get the engine running good.

Because the battery is dead, do not be surprised if you hear a bunch of rattling around inside the dash once the engine is running. The HVAC actuators will go through a recalibration sequence once the power is restored to them, and that calibration sequence stresses the old brittle plastic gears inside of them and more than likely a gear inside at least one of them will break rendering the actuator inoperable.

I would also expect the fuel system to be somewhat gummed up. This is what the Berryman B-12 is for - to dissolve the gums and varnish. I would also change the gas filter before attempting to start the engine as well.

The various computer modules will relearn all they need to know so there is no need to reprogram anything.

After you get the engine running well, rescan the ECM for OBDII codes and compare them to the ones you originally read, This will let you know where you need to focus diagnostics on.

Good Luck!

 

Thank you for the Berryman B-12 suggestion. I already tried to drain the 1/4 tank of old gas, but can't get the siphon all the way down to the gas. I think someone added an anti-siphon tool at some point. I added 5 gallons of fresh gas and have my fingers crossed. I'll change the gas filter and add the B-12 now, too. I was also aware of the need to R&R the oil before starting. I pulled all the spark plugs and sprayed in some Fogging Oil, which should have been done *before* it was parked, but I figure it might ease some friction and rusty scraping during those first few turns. I can't get a socket on the crank bolt because the fan and shroud are right up against it, but it's not worth the effort to remove the shroud just to hand-turn the engine a few revs. Bumping it over with the starter is almost as gentle. I plan to pre-fill a new oil filter and spin the engine on the starter with no plugs in it just to prime the oil pump and lifters and fill the galleys before combustion pressure hits. I see some signs of burnt oil on the #2 plug so I'll run a compression test all-round before trying to start 'er up.

Some critters nested in the engine bay over the years and I found a wire harness that'd been chewed through, with two wires cut and copper exposed all over the place, which explains the bizarre dash lights and readings I saw after charging the battery and turning the key... Here's hoping nothing important shorted to death...

In case you're wondering, the reason for this exercise on my daughter's Trailblazer is a leaky oil pan. It was parked because her husband (now ex-) wouldn't fix it (as you know, to drop the oil pan you have to dismantle the drive shaft that goes right through it) and she wouldn't let him drive it while it was leaking. When he split, he stole the truck she's been using so now it falls to me to get the 'ol 'Blazer back on the road, asap! It's out in the weeds and I don't have anything strong enough to drag it out of there, so it's got to move under it's own power to where I can jack it up and get under it to patch or pull the pan safely. Next up: Wire Splicing & Soldering 101...

It's good to know the computers should sort themselves out (if I didn't *short* them out... ;-)). Thanks. I'll keep you posted.

 

Might be a good idea to run something like diesel fuel or a mild solvent down the oil cap before you change the oil and filter, to get as much crud and moisture out as you can, but I'd not do that with the motor running. Maybe let it set for a while, so it can clean the oil pan and oil pump suction out real good.

 

Good luck and you are a nice dad!

I'll keep my fingers crossed that the critter damage to the wiring is minimal and that you don't run into any "...Holy You Know What..." problems!

 

Thanks, Chem_man! I was able to solder in 3 splices of new wire, but I had to replace the battery because it wouldn't take a charge. Ouch! $200 bucks! But now when I turn the key, the dash lights appear normal and the starter bumps the engine over. Although my daughter says the mileage is reading about 30k too low... Don't know what that's about.

Today it's all about draining the fuel tank come hell or high water, and replacing the fuel filter. That'll be fun, because it's still out in the weeds and I have to jack it up to get at the filter, but I figure I can drain the bad gas (and the 5Gal fresh I foolishly added) out of the tank from there. Then I'll put some new fresh gas in, put oil in it, spin it over (with no plugs in it), to prime the oil pump and bearings, etc,... then put some fresh gas in, start 'er up and drive it out of the weeds. Talk about "fingers crossed"! Then get 'er up on ramps, drain the oil and see about patching the oil leak in the pan...

 

Please let us know how you fare!

 

Well, I got 'er started and moved out of the weeds under her own power! She's up on ramps and ready for an investigation into where the oil pan is leaking. Oddly, it leaks a lot less when the engine is running; it leaks most when the engine is turned off. I guess that means the hole is high up on the pan, and the oil level drops below the hole when the pump is circulating the oil through the engine. Turn the engine off, and the oil level in the pan rises above the hole when it all drains back into the pan.

I still smile when I remember how quickly it started right up. ;-) It's got a misfire that I'm hoping is just bad gas or slightly gummed injectors. I'll get some fuel treatment in there and do a compression test to be sure this engine is still worth investing in...

 

Sounds like progress!