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Discussion Starter · #1 · (Edited)
Well my first reverse engineering project is to have the computer re-flashed to remove the VATS and parking lock issues in the hopes that that will cure the five second run problem. This may or may not have been done properly so I have to be sure. No problem, just remove that PCM and FedEX it to the right guy.

So first, I eyeball the computer and darn, it looks tight in there! First issue is the hatch doesn’t open far enough to get in there easily. I decide to remove the hatch to avoid the chance of damage because of limited opening (I’ll fix that further down the road).

Hatch now off. Looks like the computer is clamped in place by a bracket across the top with two screws. No problem, just unfasten it and I am done. Oops! Outside screw is inaccessible without removing rear quarter window (does everybody’s have these round access holes behind the window?). Crimminy!! Oh, this is tedious. Unscrewing much too long screws with aircraft grade (or worse, class 5) thread fit meaning more than casual force has to be applied to unscrew the screw completely out of the threads until each screw is in my hand.

Quarter window now off, but not before it pulls loose a little paint while removing (Hm-m-m-m, since there is no seal covering the cabin opening behind the window, I wonder how much wind noise comes from that?). I can now finish unscrewing and removing upper bracket.

Upper bracket now off. Computer is tight as can be but I wiggle it loose enough to pull straight up. Oh crap! The rear of the computer hits a frame tube before the computer is clear of the lower bracket that it sits in. Ok, I will tilt it back so that the front of the computer is clear of the bracket and that should do it. Oh, No-o-o-o! The wiring harness has zero slack to allow lifting up the front of the computer. I check the manual. The suggested wiring route would give some plenty of slack, but mine is routed differently. No joy here. I did notice according to the manual that the computer is installed while the body is off which would make it deceptively easy to install. And perhaps short circuit any thought sequence about future removal accessibility.

Next brainstorm is to remove lower bracket and swing computer and lower bracket out enough to get access to harness in order to remove it and complete the removal of the computer. The lower bracket is bolted to the frame. The inner bolt and nut are accessible and come off easily. Outer is a different story. The nut attaching the lower bracket on the underside of the frame attach points is not accessible by any known means in this space-time continuum. Ar-r-r-r-r-g-g-g-g-g- h-h-h-h-h! Wife sticks head into garage and asks about whimpering she is hearing. Am I hurt?

OK, my next brainstorm is to remove the appropriate belly pan and get at the spinning nut with cobbled up extensions from underneath. This will be a two-person operation but no problem.

Check under car. Holy dufus Batman, who thought this was gonna be easy? Belly pans everywhere! After buying one of those so-called Nascar style jacks that will at least fit under the car, I don’t know where to put it.

So, the question of the moment is where are the jack points for a belly pan encrusted bottom?

:batman:
 

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Since you are going to be lots of work and will need access to all the panels, I have a few suggestions:

1. Take out the seats so you have room to maneuver
2. Take out the rear "waterfall"
3. Take out the rear firewall, just behind the seats
4. Remove the rear uper firewall (where the window is)

You probably won't have to remove the belly pans if you do this.

This should take about an hour and will give you full access to the front of the motor, wiring harnesses, fuel tanks and computer.

As far as jacking up the car, make sure your jack is well padded. You can jack it up where the belly pans meet the frame. Where ever there are seams, there is frame behind it. I don't have my car here now but from memory, I jacked the rear up just in front of the rear wheels where the traingular belly pan meets the rectangular one. Sounds weird but take a look.

For the front, I jack it up just behind the front wheels. Make sure you use jack stands and don't get under the car without them.

I also created an access panel on the passenger side aluminum in front of the rear wheel so I had access the bottom of the fuse box.

Hope this helps,

Henry
 

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I usually use a soft chunk (foot long or so) of 2x4 between the jack and frame. The rivet heads will sink into the soft wood and the board will lay flat against the frame that way. Now, getting a 2x4 AND a jack under there requires you to use a very low profile jack (I use some small scissors jacks like those the the trunk of your "other" car) to get it high enough to get a real jack with my 2x4 under there.

As for getting your computer out, you should be able to get a 7mm wrench in there to get the connectors loose without removing a bunch of other stuff. I've done it before, and it is a PITA, but very doable----even with the hatch on.....so with the hatch off, I wouldn't think it would be so bad. If you're trying to do all this with the rear tire on, and the inner fenderwell aluminum in place, that may be a good place to start removing stuff. Getting the front panel wheel well alum out of the way and working thru that opening would also make your life much easier with relatively little work to get there.
 

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3Times is the charm!!

Try removing and restoring power to your ECU three times in a row before sending it off for a re-flash. I did this by disconnesting the blue and red connectors from the ecu, turn the ign. sw on, then off, disconnect again, repeat 3X. This resets whats left of the VATS and the engine will run successfully. Sorry but you still have to get to the ECU.

BTW- thanks for the ECU removal description, I posted the question of whether it can be removed with the body on and was told it wasent a big deal. Ha Ha. I'll go work out a solution because I am sure it will be coming out eventually.
 

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Just a general question of an idea I had.

Why not place the ECU behind the passanger seat within the cabin? This would protect it better and provide good accessability. The harness looks more than long enough.

BTW- People often have asked me why I sit and stare at a project for so long throughout a build. Your issue is one of the exact reasons. It's not just getting something together that is important, but how repair friendly it is that can really make a difference down the road. I put things together and take them apart in my head many times before I actually commit to placing something.
 

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I know the harnesses that I've used just barely reach to the GTM ECU placement as-is. Definitely not long enough go any further.

The only area to mount it behind the seat would be down low, toward the floor, as the top of the seat is up against the tank cover.......and therefore would require you to remove the seat to get at the ECU. Personally, I'd rather remove it from it's current location than have to pull the seat out.....which would require raising the car far enough to get under it, which is a task all it's own.
 

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Maybe it's because I have completely disassembled the harness in order to route it in front of the engine that it seems plenty long enough. Anyway, taking the seat out still sounds a heck of a lot easier than what ICABV8 is doing. I understand that it may not be the normal install that he is dealing with, but the protection benefits also look desirable to me.....if the harness is long enough, and there is room. It may also further clean up the engine compartment.
 

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crash, isn't your harness a crate harness, they are much longer than the corvette harness
 

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crash, isn't your harness a crate harness, they are much longer than the corvette harness
Well you could cut every wire running into the pcm plugs and extend the harness..... lol.
 

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Since I've had my ecu out a number of times, and got tired of removing the passenger seat, firewall, etc. I took the plastic "u" bracket and slightly modified the outboard side allowing the inboard side to actually hold the ecu in place. I used a slightly longer screw on the outboard side and left it slightly loose. Now I loosen the inboard side then lift and swing the u bracket out of the way, lift the ecu out of the bottom bracket and slightly side it back to unbolt the harnesses. It's still a pia but I can get the ecu out in about 15 minutes. Of coarse, I've had it in and out so many times everything is well worn and loose!
 

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Discussion Starter · #15 ·
Finally got the computer out by accessing through the forward fenderwell sheet metal. Thanks to Shane for that lightbulb moment. Before disconnecting it I tried to start the car and voila!, it started.

While wrestling with the computer removal from the chassis, I had invoked Ron Carter's suggested 3 times the charm starting process in his post above. What a lovely sound! I let it run for several seconds before noticing no oil pressure reading. Heck! Shut it down. No worry yet; it is probably a connection issue since the car had run a few miles when Tom owned it. I'll get to that later.

After getting the computer out, I saw the problem. After originally removing the top computer bracket, the harness should have had enough slack to allow enough movement to remove the computer. In my case, instead of the harness being routed differently not allowing that slack as I had first thought, the harness was routed per instructions but had caught on the edge of the platform under the computer thus not allowing any apparent slack. I should have tugged a little more vigorously.

Anyway, to make the bottom bracket more easily removable in the future for whatever reason, I think I will use tinnerman nuts on the bottom allowing the screws to be removed from above without requiring any access to the nuts anymore.:wiggle::wiggle::wiggle:

 
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