| LIFE OF A GT |
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 | |  | December 31, 2009 - After the big dramatic day of pulling out the engine, I continued to work.
That great engine is worthless without the wiring to run it, so I spent several days pulling out what I needed. Yanking out a wiring harness without chopping it up requires fairly substantial disassembly of the car, including pulling the dash.
GM made some weird choices when it comes to connectors. Some are the excellent GM "Weatherpak" ones. But some of the parts that appear to be sourced from the outside use a wide variety of completely different connector designs. It's a bit ridiculous, making the wiring harness appear to have been designed by a half dozen teams that never actually talked to each other.
A number of connectors are locked in to place with a secondary pin. In the picture, the orange insert needs to be pulled out (which, in this case, involved a dental pick to depress the small and difficult to access tangs) before the blue section can be removed. Why? It certainly makes the car harder to assemble and to work on. Most of the other connectors have a more common clip that can be released easily. But for some reason, there's a guy at Chevy who's paranoid about how secure a connector has to be.
entry 238 - tags: wiring | | |  | December 31, 2009 - I'm trying to isolate the wires I need so I don't need to pull the entire harness from the car.
There are probably easier ways to go about this - more on that later - but I figure I'd rather put in the extra effort just in case.
Remember those disparate wire harness engineering teams that wouldn't talk to each other about connector design? They also didn't communicate on wire colors either. There simply aren't enough colors to go around, and the common trick of adding a stripe to distinguish between say, a white wire and a white wire with a green stripe. Adding the stripe increases the number of distinct wires dramatically. Instead, the instrument cluster has two white wires coming out of it. One is for the skip shift system, the other is the speedometer signal. Both go to the Powertrain Control Module or PCM. Thanks Chevy!
Now, the easier method. I just remembered that Painless makes an LS wiring harness. In fact, it turns out they make one for the unique 1998 Camaro PCM. It includes everything you need to run the engine and nothing else - even a fusebox - and is designed for jobs like mine. As a bonus, they'll also reflash your PCM for free, disabling the need to use a key with a particular resistor stuck inside or turning off the need for rear O2 sensors. The total is right around $500. When you consider I've probably taken $500 of potential resale out of the Camaro (should it remain a viable car, anyhow), I'll have to pay for the software to reflash the PCM and I may end up spending some money on a fusebox, it may have actually been a money-saving choice to make. Oh well, I'm committed to this plan now.
entry 239 - tags: wiring | | | February 10, 2010 - I think I've sorted out how the fuel system will work.
I've ordered the always-necessary random bits and pieces. Turns out using AN fittings won't be such a problem, and this way I'll have a sexy braided fuel hose! It should come together fairly quickly when I start work. I've also ordered a muffler to confirm fitment.
I'm procrastinating. I really should be working on the metalwork around the transmission. But Janel's under the weather and asleep on the couch, so it would probably be rude to fire up the grinder, drill and Sawzall. Soon.
What I'm really trying to decide is if I should just bite the bullet and pick up a Painless wiring harness. I've wired cars from scratch before, and it's not that much fun. I've modified stock wiring harnesses, and that's possibly even less fun. It's so tempting to simply have something I can plug in with no mystery or work on my part. If it'll cut a month off the build time - that seems like a lot, but it's actually plausible especially when you consider my lack of experience with these engines - then it's probably worth it. I'm getting so lazy.
entry 281 - tags: wiring, fuel | | |  | February 16, 2010 - The folks on the LS1tech.com forum are very enthusiastic about modifying stock harnesses.
So before I dropped a big pile of cash on a Painless setup, I figured I'd give it a shot. I started by making a spreadsheet of all the wires in the ECU connectors, what they did and if they should be kept.
It turns out that even the oddball 1998 Camaro harness is very well documented. With the help of LS2.com this only took a moment. I walked through the list and put an X beside every wire I wanted. No VATS (anti-theft system), no EGR, no second O2 sensors, no fuel tank pressurization and no charcoal canister. Also, I didn't feel it necessary for the low oil signal to pass through the ECU.
All of this work was done with the Jaguar looking on, representing Lucas.
entry 285 - tags: wiring | | |  | February 16, 2010 - Nice work, GM!
The connectors for the ECU (actually, I think the term is PCM but I'm going to stick with my usual) might be huge, but after you pop off a couple of plastic covers I discovered that they're ridiculously easy to modify. Simply lift the wire terminal of choice upward a bit and lift the tap on top a bit further, then push. The wire slides right out. I used a dental pick when I was dealing with a single terminal in the middle of a bunch of others, but it's possible to do this with your bare hands.
A couple of minutes later, I had removed the wires I didn't want. If I decide to put them back later, they just push in.
entry 286 - tags: wiring | | |  | February 16, 2010 - After all the extra wires were popped out of the connector, I started pulling them out of the harness.
I'd follow them back through the other wires to find what connector they went to. I unwrapped the harness (put together with a minimum of super-sticky tape, unlike the Miata!) and used zipties to hold it in shape.
Some connectors had other wires that were shared, typically power and ground. These were chased back to junctions with other wires and snipped off. The pink power wires will have to be taped up before I energize the harness. Gradually, the harness got simpler and simpler.
I used LT1.com (no, that's not a typo) to identify some of the wires in the various inline connectors. The "keep" wires that passed through these were typically things such as gauge information, so I pulled them out of the inline connectors, coiled them up and labelled them. I also replaced a hacked-up tach wire with one of an identical color - did the Camaro previously have a big aftermarket tach?
The Jaguar approves.
entry 287 - tags: wiring | | |  | February 16, 2010 - With the harness simplified, I laid it out over the engine.
Next I had to find a place to stash the enormous ECU. It's huge! Newer ones are smaller - but I don't have a newer one. With the removal of the AC system inside the car, there's some room above the passenger's feet. It would be hard to disguise the big modern heatsinked box though.
The MGB, like many other Little British Cars, is ambidextrous and uses the same chassis for RHD and LHD applications. There are even plates covering over the holes where the pedals would pass through the firewall. This leaves a fairly large space where the RHD pedals aren't, and it's the perfect size for the ECU. As a bonus, the Camaro keeps its ECU in almost exactly the same place so the wiring lengths are almost perfect. I can even reuse the Camaro bracket.
It seems I get lucky with packaging once in a while on this project.
entry 288 - tags: wiring, packaging | | |  | February 16, 2010 - My plan has been to somehow stuff an electric speedometer inside the classic Smiths case.
The Camaro's T56 uses an electronic sender and the MG has a completely mechanical version.
Of course, I'm a long way from needing a speedo. But I'm not feeling completely healthy and poking around wires is more attractive right now than cutting and welding. Thus the electric emphasis of the last few days.
Well, it's not going to be easy. Looks like quite a challenge, actually. Enough of one that I started looking for alternatives. I already know of one, which is basically a small electronic motor in a box that takes an electronic signal in and spins a cable at the appropriate speed. It's a decent option, although a bit more of a kluge than I'd prefer. If you're converting a Miata with molded plastic gauges, you don't have a lot of other options. But the MG uses individual gauges, of course.
Poking around, I discovered that there actually exists an electronic Smiths speedo. It's not a perfect match to what I have, but it's awfully close. Close enough to work. And as a bonus, it's actually significantly less expensive than the little "gerbil box" motorized adapter. Excellent.
What about the tach? It's expecting a four-cylinder, so it'll read twice as fast with 4 pulses per crank revolution instead of 2. Some poking around pulled up an article on the British V8 site that explains how to add a potentiometer to easily make the tach adjustable. But wait, it gets better. 1972 was the only year to be fitted with a potentiometer from the factory. At the time the article was written, it wasn't known if this gave enough range to make it work with a V8, but I'm very willing to find out. If not, I'll just solder in a different one. Perfect.
entry 289 - tags: gauges, wiring | | |  | February 26, 2010 - Parts are starting to arrive from all over!
Del City provided this 10-circuit fuse block. I figure I only need 6, but more can't hurt. The MG only has about 4 and they're all devoted to lighting from what I can tell. If I only need 6 of these 10, I'll integrate the two boxes.
I also picked up a big master circuit breaker. It'll give a bit of "uhoh" protection. It also lets me cut the power to the whole car, which is really handy when it comes time to work on things or to store a car for a while.
Most of the post-header exhaust parts are here as well, and the big box from AFCO will arrive Monday. I'll have no excuses for not working on the car shortly!
entry 297 - tags: wiring, exhaust | | |  | May 27, 2010 - The first step in the fuel system - at least, from the point of the fuel.
The flare on the fuel tank is some weird British size, so I attached a new fitting to a short piece of the original fuel pipe. The fit on the compression fitting is so tight that I had to stick the pipe in the bead blaster and clean off the surface crust before it would slip over. The cleaner pipe will help it seal as well.
The two missing adapters I need showed up today in ludicrously large boxes, so I have everything I need to finish the fuel lines. I also started working on the wiring, and I've decided where the ECU will go. It'll be fairly straightforward from here.
entry 337 - tags: fuel, wiring | | |  | June 16, 2010 - Wiring time!
This means I'm referencing a handy four-page schematic of the Camaro wiring, the one-page diagram for the MG and referring to the big 100-page book of Miata wiring once in a while. The Camaro wiring is actually going pretty well. The biggest problem is hunting down and fixing a couple of connectors that were damaged either when I pulled the engine or beforehand.
Integrating it into the MG wiring is a bit more challenging, although it did help when I figured out I was trying to reinstall the MG harness the wrong way in the car! I think I need to make a photocopy of the MG diagram and start identifying which sections to keep and which ones will be deleted.
Sharp eyes (and real obsessives) might notice that I've flipped the fuel rail over on the engine. This puts my fuel feed on the passenger's side instead of the driver's. It's just a bit easier to run it that way. Let's hear it for symmetrical intake manifolds!
entry 346 - tags: wiring, fuel | | |  | June 16, 2010 - One of the big roadblocks to the wiring was figuring out how to mount the massive ECU.
As you may remember, I was originally going to put it in the engine bay, but that was a pretty tight fit. I was also trying to reuse the stock bracket, and that was proving to be difficult. There's a bracket from the S10 or some sort of van that is a bit easier to mount in a non-standard location and arrangement, but I finally realized I could simply mount it with a solid strap, as seen here. It's solid and secure, but easy to remove when needed.
The ECU is located at the end of the passenger's footwell, which means the wiring harness can easily drop down through the hole that would have been used for the pedals in a RHD car. Cool. I'll probably put a plate over top of it to hide the ECU and give the passenger a good solid foot rest - but not yet.
entry 347 - tags: ECU, wiring, packaging | | |  | June 16, 2010 - The GM computer needed a few new circuits.
The MG only has five fuses (that I know of) in the entire car, but I wanted more than that! To be fair, one of the fuses in the new box is a duplicate of the fuel pump fuse in the old one - I'm not sure if I'm going to retain that particular one.
The wire colors here are the GM ones, they're quite fond of pink wires. Thus the labels. The wires will be corraled further when I'm done as well, right now they're just being roughly loomed together.
The new fuse box sits in the engine bar, where the pedal box would be on a RHD car. The square hole at the bottom of the picture is the one that lets the wires run down to the ECU, which is just barely visible in there. I'll adapt the factory cover to make this look good.
entry 348 - tags: wiring | | | June 23, 2010 - Work continues, but not too quickly.
I've been moving slowly - but the main power lines from the trunk-mounted battery to the starter, alternator and main breaker are now all in place. The breaker can be tripped manually so I can kill the power to the car if required.
I'm now trying to figure out how to run the original MG wiring harness up to the front of the car. It'll continue to handle housekeeping chores like brake lights, fuel level and turn signals. The problem is the hot exhaust criss-crossing under the car - I want to keep the wiring clear of it. The main power line runs through the transmission tunnel, but the MG harness is about 4-6" too short to work that way. I'll play with it again tonight and see if I can find a bit of extra length.
entry 351 - tags: wiring | | |  | September 3, 2010 - Time for the wiring to commence.
I have a few Miata parts (ignition switch and the headlight/turn stalks), a whole bunch of GM parts (the whole point of this project, really) and the leftover MG parts (ie, housekeeping). So I'm having to do a lot of cross referencing and some mental redesigning. It's kind of amusing - the MG diagram is one 8.5x11 page. The GM engine diagrams are on four 8.5x11 pages. And the Miata book is about 120 11x17 pages. But it's more useful!
entry 386 - tags: wiring | | |  | September 3, 2010 - The ugly truth.
There's a spot in the engine bay above the passenger's feet where one of the main MG harnesses erupts from the fender. Just below that, I've mounted the GM computer and rerouted the other main MG harness through the cockpit to arrive at this same location. It's quite a traffic jam.
I'm tracing through the MG harness to pull out unused wires and to figure out how some of it works. I'm doing a lot of electrical forensic work as I try to identify a number of the connections. I know there's a hookup for the reverse lights in there somewhere...
The first splice between the GM and MG harnesses was made yesterday - the alternator light. The ignition switch is also wired in, so I can check that the appropriate circuits will be energized when the battery is installed. Since the MG harness has a few unknowns for me, I'm being particularly careful to avoid stray electrons.
entry 387 - tags: wiring | | |  | September 3, 2010 - I do love my bead blaster.
This is a relay for the starter solenoid - probably added to the MG over the course of production to protect the poor ignition switch from the power needed to trigger the solenoid. The Miata switch is robust enough to handle it, but the wiring in the MG harness is a little smaller than I'd prefer. So I'll keep my relay to trigger my solenoid to trigger my starter. At least, that's how I'm thinking now.
Just look at what 20 seconds in the bead blasting cabinet did to this (probably) 38-year-old component. There's no corrosion on those contacts!
entry 388 - tags: wiring, bead blaster | | | September 9, 2010 - Power!
With a few spare minutes in the garage and a freshly connected main relay, I hooked up the battery to the car for the first time. First, of course, I had to come up with a good grounding point. Hopefully I did.
When I connected the battery, nothing happened. That's good.
Then I flipped on the main circuit breaker. Nothing happened. That's good.
Then I turned on the ignition and saw a light come on inside the dash. Must be the alternator light. I also heard the main relay click over and the fuse panel for switched power came alive. That's good!
No sparks, no shorts, no nasty smells. All the smoke stayed inside the wires. This may not seem like a big step, but now that I know I have a smoke-tight electrical system it'll be a lot easier to trace wires and determine that everything is hooked up correctly.
Woohoo!
entry 393 - tags: wiring, smoke, electrical | | |
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