The GTM Supercar Build Log

Archive for the ‘Wiring’ Category

RaceLogic Traction Control Installed

Thursday, June 21st, 2012

I’ve been meaning to get this post up for a while now, but better late than never!

Last month I finished the installation of the RaceLogic traction control system. I can say this system is pretty amazing now that I’ve put a few hundred miles on it and have played with it a bit. The RL system monitors all four wheel speeds and when it detects slip, misfires the engine using preset cut patterns. The cuts are so seamless I rarely notice the RL system stepping in – it just feels like the car has tons more gripping power.  I have not messed with the launch control system yet, but plan to play with it more over the summer.  The system allows you to dial in 0 to 25% of allowed slip. 0% being ‘wet mode’ which allows zero slip, and only 5% in a straight line.  The system is very customizable once you hook a laptop up to it, allowing you to change fuel cut patterns, straight line slip allowance, etc. I have left everything at their defaults.

On to the installation:

The first task was getting to the injector wires in the engine harness. Not the most glorious task, but not real difficult either. Once the wires were isolated I picked a spot where I wanted to mount the RL logic box. I choose above the left side of the engine bay – seemed to be the best spot for it. The harness RL provides to the injectors is very short, so I had them ship me a much longer harness so I did not have to do a bunch of wire extensions to get the logic box injector wires to the injector wires in the harness.

Once I had the harness, weatherpack connectors were used to connect the RL injector signal wires to the ECU/fuel injector signal wires. This allows me to return the car ‘to stock’ in case the logic box fails for some reason (which would prevent the car from starting).  The RL logic box acts as a go-between between the ECU and injectors. ECU runs to the RL logic box, RL logic box outputs to the injectors.

With the harness done, some  additional logic box and digital controller wiring had to be done. A wire taps into your RPM signal (I used the wire coming from the ECU, in the tunnel), and you have to route a +12v switched power source to the digital controller and logic box. The logic box connects to the digital controller via a serial cable. I opted to put the digital controller just ahead of the engine cover/water fall below the shifter.

The last task was to connect the 4 wheel speed sensors (I used the already-present ABS sensors in the Corvette hubs, with new GM pigtails) to the harness wheel speed signal wires. Another weatherpack connector was used for this, for simplicity sake.

Everything was finished with any necessary grounds being routed to the chassis. The wheel speed signal wires are shielded so I just grounded the ground wire in each wire bundle to the chassis, along with the signal grounds.

I’ve included the wiring schematic I drew up with the pics below.

Push-button Start with RFID Security Installed

Sunday, July 17th, 2011

I finally decided to tackle installing the 2go-keyless push-button start system I picked up last fall. This is a pretty straight forward modification. Easiest way to tackle this, for me, was to go in from underneath. With the underbody aluminum out of the way there is some decent working room to make the necessary wiring changes, and install the controller box.  The old ignition was removed and the ignition wires were connected to the control box harnesses (only 4 wires to join up).  The start switch plugs right into the control box. A programming switch is installed under the dash ‘just in case’ the key fob fails and I have to manually start it. With everything in place I covered the control box in Thermotec heat shield and stuck it up inside the tunnel with some heavy-duty 3m adhesive tape. Harnesses were then connected, switches plugged-in, and ground established.  The only real trouble I had was once everything was tested and buttoned up, the system stopped working. After checking all my wiring, re-doing the ground connection, etc., I realized it was due to a faulty (or improperly programmed) fob. During my previous tests before cleaning everything up I had used the ‘backup’ fob. At least that one works.

The system itself is nice. The start button lights up when the car is running and flashes every second when it is ‘armed’ when the car is off. The keychain fob can be put into a manual or automatic mode. Manual requires you to press the button on the fob while starting, automatic is completely passive – just need to have it on you when starting the car. The range for the fob detection is about 10′. The start button itself can be lightly pressed to turn on accessories. Pressing and holding starts the car. Definitely nicer looking than the standard key ignition.

Fog Lights Upgraded

Tuesday, May 17th, 2011

Today I installed the new fog lights I had purchased for the GTM over the winter. I’ve been dying to swap out the generic fog lights that FFR supplies with these new Hella Optilux 2500 lights. These lights are way brighter than the stock lights, and have sharp looking halo LED lighting accents. I’ve never felt that comfortable with the GTM’s lighting on prior twilight drives, but these new fogs make all the difference.

Since the lights use separate wiring for the LED halos and the 55w halogen bulbs I decided to hook up the halo rings to the parking lights, and the fog lamp switch remains dedicated to the main bulbs. The bracket that comes with the lights is a ‘hanging design’ bracket, so I had Josh modify them so they could be surface mounted in the fog light recesses. A carriage bolt was inserted into the bracket to bolt it in place using the previous fog light holes. I’m really pleased with the look of these lights.

Warm-Start Fixed, Driving Ensues.

Wednesday, August 25th, 2010

Last night I was plodding through my log data for the drives and failed warm-starts I made this past weekend, looking for clues or anything that would help shed some light on the problem at hand, and I found something peculiar. Every failed start, and every warm-start that idled a bit then died, all failed with an IAT of -38. Some quick research shows that the LS computer seeing an IAT of -38 means it thinks the sensor is disconnected/unplugged. The sensor was obviously still in place, so I knew I had a potential problem. In the past, the -38 had shown up during idle tuning, but I assumed it was a software glitch as it only showed up for a few frames here and there. The computer thinking that its -38 out when it’s really 95 poses a problem.

I first tested the IAT sensor by using a multimeter and a heat gun. To test the sensor you just need to measure resistance by putting the multimeter on the 2 prongs on the sensor pins, and heat it with a heatgun. An ambient temperature of 80-85ish will yield a resistance of 2.15 or so. As the sensor gets hotter the resistance drops. I was looking for that ‘-38′ glitch to occur (ie: random jumps in resistance measurements). It never did. My sensor was working flawlessly. Next, I moved on to hooking up the laptop and scanner and monitoring the IAT while I wiggled wires around. I was not confident at all that this would yield anything as the problems only occurred with a warm engine, but…you never know. Within 20 seconds I found the wiring fault that was causing my IAT readings to bottom-out. The IAT sensor signal wire from the engine harness was damaged in the plug that connects to the MAF/IAT sensor harness. I was able to duplicate the -38 reading at will, so I went to the local Chevy dealer and got a new pigtail ordered. In the meantime, being impatient and having hoped to get the car out for its first ‘public appearance’, I snipped the IAT sensor, surgically removed the bad wire segment from the connector pin, soldered a new wire on, put the connector plug back together, spliced it in. Viola – 100% working IAT sensor. This means it’s time to drive and see if anything has changed.

My first drive on trafficked roads took me to my first stop light, introducing the GTM to a busy intersection and testing my nerves hoping it wouldn’t stall out of its idle with 10 cars around it. All was fine, though, and I made it a few miles down the highway to the gas station for the GTM’s first gas station fill-up.  I remember others stating how slowly you have to fill up the tanks, so I took 10 minutes to add 6 gallons of fuel, and explain to another customer why the GTM appeared to not have a steering wheel. Most of the Kwik Trip work staff had vacated the building at this point and were all standing 20 feet away watching and grinning. Wow, really? Perfect time to see if I fixed the warm-start issue by repairing the IAT wiring. No pressure. The GTM fired up, I exhaled, and got out of there. Another stop light  and I hit the highway, then some back roads, which brought me back around and eventually home. Everything ran well, temps stayed below 200, stability was great at speed. Bump steer could use some tweaking, and I learned quickly how sensitive the manual steering is on this beast. I was pleased to find that Slayer could still overpower the 408ci LS2’s drone, via the Blaupunkt thin series components. Initially I reported I hated the rear view mirror; it’s not so bad now that I’m used to the vantage point of the driver’s seat, and it still has its uses, even if I can only see the lower half of the bumper of any vehicle right behind me.

It was my father-in-law’s birthday today, so I invited him out on the second drive, now that I was somewhat confident handling the GTM. The GTM started right up, so it seems the warm-start issue was nailed. 20 miles later after visiting my favorite WOT playground and slow city driving we returned safely. Some choice descriptions of the GTM experience from my father-in-law included ‘that scared the shit out of me’ , ‘that thing is terrifying’, and ‘my legs are still shaking’. His constant grin was the best feedback, though. Good times, and I can say the GTM gets to triple digits awfully fast.

Now the only thing I am really concerned with fixing is the threat of stalling after quick stoppages.  If I stop the GTM quickly the engine comes awfully close to stalling out. Not a huge issue, but it’s not something I want to be worried about every time I come to a stop anywhere – especially in traffic.  I am also researching cameras for shooting in-car video, so hopefully I will get some decent drives to post soon.

New Steering Wheel Installed

Thursday, August 19th, 2010

Got the new steering wheel today so I installed that.  The outer portion of the quick disconnect bolts to the back of the steering wheel, horn is connected to the quick disconnect wiring and pushed/inserted into the quick disconnect piece. I had some troubles getting the quick disconnect to work at first – I could not lock the wheel into place. I realized that one of the bolts that holds the steering wheel onto the disconnect piece was rubbing on the inside of the main disconnect hub so I had to grind that down a bit with a file.  Now it locks/unlocks as it should.

This setup is very nice. The steering wheel can be removed or connected in seconds, and getting in and out of the car is much, much easier. This steering wheel allows for a great view of the gauges, as it follows the curvature of the dash nearly perfectly.

Diffuser Prep, Tuning, Other Misc Stuff

Friday, July 16th, 2010

I haven’t posted in a few days, but I’ve been keeping busy with small tasks here and there:

- wired up the rear view mirror
- fine tuned the intake tubing positions so that they are ready for mounting when I get the intake duct mesh silicone’d in
- formed the exhaust and intake duct mesh pieces; dropped them off for powder coat
- picked up louvers from powder coating, will install on diffuser soon
- prepped diffuser by drilling more rivnut/bolt attachment points to the body to make it sturdier
- Josh finished the exhaust mount, waiting on a new mandrel to install bigger rivnuts to mount it and complete the exhaust
- making progress on getting the motor running properly: installed a Nick Williams 96mm tb, and am currently working on tuning it with HP Tuners. Motor runs if I stay on the throttle at 1000rpm or higher, but it dies if I let off.

At this point the interior is complete, and all that remains is buttoning up the exhaust and intake, creating a heat barrier between the two, installing the exhaust and intake mesh, and installing the louvers and diffuser.  I also need to get the motor to idle, too.

Mirror Wires Routed, iPhone Holster Mounted, Tunnel “Gap Cover” Fabbed and Installed

Saturday, July 3rd, 2010

Instead of using the FFR provided rear-view mirror I decided to use the Corvette rear-view since it has driver and passenger map lights built in. To utilize this lighting, I had to run a ground wire, and the white ‘dome light’ wire from the Painless fusebox up to the center of the windshield where the mirror will be. Not an easy task with the roll-bar padding/fabric in place! I ended up snaking a coat hanger down the pillar under the fabric with a hook bent on the end. Once I got it down behind the dash I was able to hook the mirror wires and pull them up the pillar. I then pushed the wires on top of the front halo bar (sandwiched between the roof and halo bar) and ran them to the center of the windshield. Tested the mirror wiring to ensure it will work – good.

Since my radio has a really great iPhone interface, I mounted a nice iPhone holster on the driver side for easy access. This holster is actually designed to mount on vents, but I just unscrewed and removed the mounting mechanism it uses and affixed it to the tunnel vinyl with heavy-duty double-sided tape. Perfect setup.

Lastly, for some reason FFR leaves a nice ugly gap between the engine cover and dash console. They don’t tell you to cover it, nor do they supply a piece to cover this gap. To fix this a cover has to be made. I cut a piece of cardboard and bent it to fit over the console and engine cover edges to get a basic measurement of the aluminum piece I would need. I have a handful of aluminum scrap left over from the build so I cut a piece to match the cardboard and bent it to match the tunnel sides. 1/4″ holes were drilled on each side, and then the tunnel frame holes were drilled out and rivnuts were installed. I trimmed the aluminum piece a bit more, then covered the top with some 1/4″ Dynamat for padding.  Left over suede from the build was used to cover it. Bolted back in place, the cover actually makes for a nice elbow rest since it’s padded fairly well. Not bad.

Driver Dash Installed

Saturday, July 3rd, 2010

Finally, the interior is nearly complete. With the driver dash pod re-glued and ready for install I cleaned up some wiring that will be under the dash, wired the transmission oil cooler LED indicator, then installed the pod. Before riveting in place I attached the air duct and dash switches for camera and lights. Dash pod was then riveted into place, and then the gauge face was plugged in and screwed down.  I then threw on the steering column cover and screwed that in place.

Gauge Face Wiring, Speedo and Tach, Other Misc Wiring, Driver Dash Pod Re-glued

Tuesday, June 29th, 2010

Over the last couple days I have taken care of a handful of small tasks.

The driver dash pod vinyl had to be re-glued after pulling it back to trim the fiber glass back. Got that taken care of. The pod is ready for reinstall once I get the wiring straightened out for the dash.

Organized and loomed up the reverse/backup switch wiring and license plate LED light wiring. I used standard 14-16ga bullet connectors for the reverse switch, but I used a small screwdriver to widen out the sides of the connector so it created a snug fit with the Porsche reverse switch. Tested the reverse lights and backup camera auto-activation – good to go.

Soldered the turn signals and high-beam LED indicators on the gauge face. All the gauge face wiring runs through a pair of weatherpack connectors now for easy plug-n-play. I wired the speedo and tach up as well. The speedo and tach are a bit trickier as you need to use a resistor for each. In a nutshell, you need to place a 1/4 or 1/2watt resistor on the +12v power wire that the tach and speedo use. After the resistor the 12v wire Y’s off – one wire goes to the gauge, the other goes to the computer. With the gauge face all wired up I plugged in the weatherpacks and gave the gauge face a quick test. Looks like everything is a go. I need one more weatherpack connector pin for one of the connectors – after that is in I can install the dash pod. I will also be installing a trans oil cooler LED that will illuminate when the oil cooler is on, so I extended the wires for that so they are easy to solder to the LED when that arrives. Picked up a few switches for interior lighting and front-camera/video activation (so no need to pull the e-brake to allow for video viewing). These will probably go in the driver dash pod on the left side.

I also trimmed the hood release mounting plate so it looked cleaner than just a big clunky square.

Passenger Seat Completed, License Plate LEDs Wired

Saturday, June 26th, 2010

Today I finished up bolting the passenger seat in, and then wired up the license plate LED lights. The seat was a chore, as it took forever to get the bolts to line up perfectly with the rivnuts at the front of the seat. Also, since rivnuts and I get along so well, I ended up having to re-tap the rivnuts at one point since they got scuffed up trying to line up the bolts blindly. All good though, as the passenger seat is rock solid.

Afterwards, I soldered up the LED wires and connected them to some quick disconnect plugs and spliced those into the taillight wiring.