Not a mopar - 2002 Trailblazer question

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mccoymail

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Sorry guys if this is in the wrong spot but I'm in a bind.

My dad has a 2002 trailblazer, 4wd, 6 cylinder.

He paid someone to fix some PS lines and they hosed something up. They put in 2 new coilpacks. New crank position sensor. New ignition switch. New oil pressure sensor. Rebuilt PCM. WHY??? Well..

It runs for 10 seconds and shuts down when warm. Runs for 10 minutes cold.

I found out he had a bad battery and replaced it.

Here is the weird part. The damn thing runs fine if I start it up and unhook the battery immediately. Ran it for 45 minutes on the alternator. Hook the battery up and it shuts down after about 1 minute.

I'm LOST and could use some help with ideas. Again, runs with no battery, dies when battery is hooked up.
 
Do NOT run the engine with the battery cable off, It can damage the PCM. The ignition switch will only cause a problem with no crank. You need to 1st check all the grounds on the engine if they are tight make sure they have a clean connection. take both battery cables off and clean, make sure they are tight on the battery. does the engine light turn on when it is running? if so what are the codes. when they replaced the crank sensor did the relearn to the PCM. was this a problem before work performed? Do you have any other warning light turning on when engine is running?
 
No codes. No warning lights. Battery terminals are cleaned, greased and tight. Grounds have been checked, cleaned and tightened. Not sure what they did to the PCM.
 
No anti-theft lite/warning? The VIN is programmed into the ECM/PCM & the IPC(gauge cluster), if they don't recognize each other it will shut You down. They need to be "learned"
or written w/the new VIN.
 
Didn't replace the pcm myself si I assume it was programmed. Can I relearn it at home? No anti theft warning. No warning at all of any kind.
 
mccoymail said:
Didn't replace the pcm myself si I assume it was programmed. Can I relearn it at home? No anti theft warning. No warning at all of any kind.
Click to expand...
Can't remember off the top of my head, but the "home learn" is a key on & tap the starter & wait sequence, more than one cycle. Been years since the last one I did, google the
trailblazer forums for it, or find someone w/shopkey..Mitchell on demand etc........
 
moparlvr166 said:
Do NOT run the engine with the battery cable off, It can damage the PCM. The ignition switch will only cause a problem with no crank.
Click to expand...
Worn/dirty/weak contacts in that ignition switch can cause all sorts of issues. I had a chevy Lumina ( retired police car ) here that would do al sorts of weird stuff. Fail to start, then later start as if nothing amiss, then shut down randomly, even short cycle the fuel pump with the hazard flashers on at ign' switch on ( BCM going off and on via a back feed ).
After being towed a few times and a small fortune spent by the owner, Taking that switch to the work bench and cleaning/tweaking those contacts cured it.
I can't know this is your problem but I would definitely use my experience, do what I did, to know it wasn't the root problem.
 
Thanks guys. Relearning the pcm and a new battery without a dead cell has helped the startup and idle issues but now I'm chasing a bad coil. No idea really what helped the original problem. Dirty connection maybe.
 
Us old-car guys have no problem finding a bad coil-pack. Our clamp-on timing lamps and still useful, just clamp to each spark wire and flash it at your belly. If it doesn't flash - bad coil. I found that 1 of the 3 coils in my 2002 Chrysler 3.8L was bad since the plug wires off it (#2 & #5) didn't make it flash (wasted-spark system). I also heard a faint clicking inside the coil-pack. I 2nd, "don't remove a battery cable when running in 1990+ cars".
 
mccoymail said:
Thanks guys. Relearning the pcm and a new battery without a dead cell has helped the startup and idle issues but now I'm chasing a bad coil. No idea really what helped the original problem. Dirty connection maybe.
Click to expand...
Why chasing? If You have a misfire the OBDII will call out exactly which cylinder(s) are missing, it will also count the exact number of misfires since the last time the data was
cleared/reset. One more thing to check is GM used ground terminal "gang buss" units attached to the underhood & other areas, which oxidation/corrosion renders the grounds
sub-par. I've cleaned these & occasionally had to move a terminal to a "blank" position if available to fix blower motors not running etc., anything attached is game.
 
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