04 trailblazer I'm having issues coil went out blow the fuse for pcm1

#1
Replaced number 6 coil and fuse no more grounding issue still won't fire up noticed number 2 was getting hot coil was getting really hot changed it to for good measures but hit it with stupid fluid nothing so no spark double checked ground plugs nothing one thing that struck me as not right is I'm getting 12 volts to crank sensor and I believe I should only be getting 5v crank sensor giving me funny readings to .think that's pcm failure but I want to really test pcm before throwing parts at it fuel pump kicks with key on can't really hear it's it comes on While I'm cranking
 

MRRSM

Lifetime VIP Supporter
#4
Before you attempt anything suggested on this List... Remove all of the Coil On Plugs and spray out the Spark Plug Wells using Scott Shop Towels to capture any Oil or Water or Dirt ...lest that stuff drain down inside of all of the Cylinders when you remove the Spark Plugs. Use either "Canned" Air or Compressed Air to ensure this first task is done well.

(1) Disconnect the Negative (-) Battery Cable for at LEAST 30 Minutes.
(2) R&R the Three Connectors off of the PCM after spraying them out with CRC Electrical Solvent
(3) Pull all (6) Spark Plugs... Line them up in order and shoot some images for us to see.
(4) All (6) Plugs should be Bone Dry and appear "Fried Chicken Brown"... Or NOT.
(5) Advise whether or not ALL or some of the Spark Plugs are also WET with Gasoline.
(6) Are the Spark Plugs OEM ACDelco or some other Make ...&... Over or Under 100,000 Miles of use?
(7) Have you tried in error to GAP the Spark Plugs or install them right out of their Boxes?
(8) Re-Install the Negative (-) Battery Cable... Pull the Fuel Pump Relay and Turn over the Engine.
(9) Allow the Engine 2-3 15 Second Periods of Rotation to evacuate any Pooled Fuel inside.
(10) Install New ACDelco OEM Spark Plugs if needed or spray out-install the Old Ones with CRC.
(11) Re-Install the Fuel Pump Relay... and Try to start the Engine WITHOUT touching the ACC Pedal.
(12) If the engine starts... let it idle for a few minutes B4 using the ACC Pedal to raise the RPM.
 
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MRRSM

Lifetime VIP Supporter
#6
I probably should have explained with better details on how to arrange those Spark Plugs for their comparison Images. What I had in mind was to view them arranged so that they are like Six Guys standing in line at a Bus Stop... with the Camera positioned overhead to look right down into each Electrode Chamber... and compare them as arranged...1-6 and see which of them was either better or worse in the way of having Excess Carbon Deposits.. and likewise a view of them all from the side to capture the condition of their Platinum Coated Tips and the Gaps .

125 PSI is a bit low for a decent "Dry" Compression Test... and knowing which cylinder that Low Pressure was on might explain whether the same Coil On Plug was misbehaving. Your engine might be a good candidate for an ACDelco Top Engine Cleaner Soak to De-Carbonize the Pistons, the two compression Top Rings and the Upper Combustion Chambers as well, This will take Two Cans of this Stuff to be Done Right With the Spark Plugs Removed... Shake the Can well... and Spray into the Spark Plug Holes.

This stuff will initially Foam up quite a bit... and after an overnight soak... Pull the Fuel Pump Relay... and Turn the Engine Over two-three times for around 15 -20 seconds per roll and have the Spark Plugs Wells stuffed with Scott Blue Shop Towels... NOT regular Paper Towels or Terry Cloth Towels. If you fail to do this... and you prematurely put the Spark Plugs back in with this liquid stuff down pooling down inside of the cylinders... When you try to turn the engine over... the liquid TEC will cause the pistons to Hydro-lock the Motor... Bending the Connecting Rods and Ruining the Engine.

After this Black Goo of Carbon Mudd is evacuated from each cylinder ...Re-Install each NEW Spark Plug and Re-Install the Fuel Pump Relay before trying to start the Engine. If the Engine Starts... let it warm up for around 5- Minutes... and Do NOT race the Engine. Then turn off the Motor... And CHANGE THE OIL & OIL FILTER to the MOBIL1 Brand. A follow up Compression Test... Both "Dry" and "Wet" should be performed once the Engine is stone cold. This is the Only Stuff to Use to any real effect for the De-Carbonizing procedure:

https://www.amazon.com/dp/B007Q102AE/?tag=gmtnation-20


 

djthumper

Administrator
#7
From what I can tell by the photos you posted, it looks like the electrode is burned down and they all need replacing.
 

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