How do you know you can't do something if you haven't tried


Things finished today

  1. Viper alarm with car starter is 100& wired in (No small Feet, this took most of the day). I also found a place to mount it.
  2. AC Compressor wiring is 100% complete, wired into factory ECU.
  3. AC Air unit is 100% complete
  4. Heater Bypass is installed and wired in
  5. Ign switch is 100% wired in.
  6. All relays are 80% wired in. (Fuses are all installed, Diodes are installed,
  7. Master fuse is installed and 30 amp self resetting fuses are installed for the Engine harness/Painless harness/AC unit/Fuel pump
  8. Hazard lights wiring is complete (diodes installed)
  9. Fog light wiring is complete.

if i can find time tomorrow i will

  • Wire the rear lights
  • Wire the Front lights
  • Wire the horn
  • Wire the wiper spray pump
  • Wire the column switches
  • Extend the wires for the gauges so they fit better.

More GTM Progress

I ended up taking a week off away from the car, stuff kept coming up, one night we had over a foot of snow fall over 2 hours and my family and i got stuck on a hill (on a highway) in the middle lane. There were 100+ other cars stuck along with us, even the snow plow that came to save us got stuck right beside us... fun night. My oldest son has been having some medical problems lately so we have had a variety of doctors appointments, Xrays, blood tests, etc. We have pretty good handle on everything now so life should be getting back to normal around here.

I didn't mention before but someone broke into my car the other day, took the garage door opener and used it to gain entry into my garage while my family and i were asleep. They stole all of my hunting gear and seemly random tools and parts from around the garage. The annoying part is not that they stole thousands of dollars worth of stuff but more that fact that ever time i go out there and try to find a part i get frustrated because i don't know if i misplaced it or if it was stolen. The latest one i noticed was a bucket i had filled with new AN fittings, it also had the little wire for calibrating the gauges in it along with the wires for controlling the gauge backlights..... Gone!. I ordered two new cables from SpeedHut, cost was about $26USD, but shipping was $44USD. So those two small cables just cost me $100 Cad... arg. So far i have counted up $4000 worth of missing tools and parts. 

KGTM was nice enough to send me his unused floor vents. 

I found this picture from an old post made by Shoeless, this is how he made a opening for those vents just under the AC unit. I plan to install them just like this. Should be fairly easy to drill holes on each side then make two straight cuts with the side grinder. I did think about making these openings above the AC unit but that wont be possible, space up there is at a premium.

here are the cancer causing grommets installed. I love these grommets, they will seal very well and can be sized by cutting away the back half of the grommet. After i ordered these i saw a post where someone just took a PVC pipe and put it straight over and sealed around the pipe. Thats a great idea, if i had do do this again i would do it that way as it would provide more space, and after the dash is closed up it would remain accessible.

I realized i have not had a picture of the whole car in a while, truthfully its less together now then it was a month ago... two steps forward, sometimes 5 steps back 🙂

My Alarm finally arrived, its a Viper 5706. It has remote start, alarm, vibration sensor, tilt sensor, window roll up module, 2 way remote, and it has a phone app with GPS tracking. I am installing this unit now because it has to wire into all of the core cars systems like ignition, door sensors, hood switches, windows, door locks. I have to find a home for this somewhere up under the dash, space under there is hard to find right now.

I complained before that FF didn't supply the fog light wiring. I was wrong, they did supply it, it was in the packaging for the fog lights themselves. They come with a switch, fuses and a relay holder. I think i will just use some of the raw wire around the car, I will cut out the fuses, relay and switch.

For the headlights/brights and daytime running lights i did something a little different. I wired the headlights to be always on (along with the tail lights). This fits my countries laws for day time running lights. The headlight switch on the stalk now controls the fog lights when headlights are selected. Switching on the brights will turn off the fog lights and switch the headlights to brights. This also helps me remove one more switch from the dash.


GTM Progress

The horn ground ring had to be modified to fit. This is what i had to do. After i cut off the majority of the collar i used a file to remove the sharp bits. 

These are the two relays for the VA unit. I had to remove these connectors to fit the wires though a grommet.

These are the new door switches i bought. Not to be installed soon, need the body on first. They just arrived in the mail.

This is the new electic mirror control switch, Also just arrived in the mail.

Door unlock solenoids arrived in the mail as well.

I hooked the mirrors up on the bench and verified that the motors work and the wires work the way i think they do. I still need the connector for the switch before i can test the system as a whole.

I adjusted the fuel pump filters to make room for the factory five cold air intake. I think this will leave just enough room. It will make it a little hard to read the fuel pressure gauge but i dont see that as a big deal.


Power Mirrors

I bought a mirror switch that i liked the look of for $26CAD on Amazon

Now that i have a switch i need the wiring pigtail for it. I have 2 options:

  1. Get it from one of the vehicles on this site and cut it off. (junk yard run)
  2. buy it new.

Here are the mouser part numbers and prices to but it new. (about $3.00)

Now we need to figure out the pinout. Lucky for me someone has already figured that out.

So onto how we will wire this up. I think 18 gauge wire should be sufficient for this task. Now i may have the polarity wrong on this diagram, so up may be down, down may be up.... i need to wire it all up on the bench first to see if this is right. If this all works out i only need 4 wires to travel from the drivers door to the passenger door


So far this is my wiring, i know some of these dont technically need relays but it makes me feel better having them. I couldnt find the maximum amp raitings of the column controls so this is the safest option and easy to diagnose.

  • All painless wires are used as low current inputs (so i can downgrade the painless fuses to match).
  • All painless + triggers are brought into relay terminal 86 so the integrated diodes can do their job.
  • Fog lights and headlights will function properly and not operate at the same time (as per code here in Canada)
  • license plate and marker lights will work (as per code here in Canada)
  • All high current circuits get their own fuse (these are integrated into the relay block)
  • hazard lights will work using 2 diodes
  • Day time running lights (as per code here in Canada) will be accomplished by just wiring past the switch and leaving the lows on all the time (including tail lights)
  • Turning the high beams on will turn off the low beams
  • door locks will be compatible with the Viper alarm i am installing
  • AC compressor uses the factory PCM, (so i can remove one relay from the Vintage Air harness)

GTM Wiring

OK, onto the body portion of the wiring. Some of this may be wrong, looking for feedback

5 pole relays
- #1 High beam relay (use the 5th pole to disable the fog lights when the high beams are on)
- #2 Door Locks (lock)
- #3 Door Locks (unlock)
- #4 Column In ? (this may be low enough current to not need a relay)
- #5 Column Out ? (this may be low enough current to not need a relay)

4 pole relays
- #6 Fog light relay (wired through High beam relays off pole)
- #7 Park light relay
- #8 Horn
- #9 Brake Lights

Engine Bay relays
- #1 AC Compressor Trigger
- #2 Fan 1
- #3 Fan 2

- Hazard lights (left signal)
- Hazard lights (right signal)
- AC Compressor

Hazard lights.
I am going to wire them up like this photo
Attachment 106028

Brake lights
At the peddle the switch needs 2 wires, one to the PCM to cancel cruise and the other to a relay to run to a relay that operates the brake lights.

Fog lights.
The fog lights cannot function at the same time as the high beams in my province (this is in the government regulations document). I plan to use the 5th pin on the high beams relay to deliver power to the fog light relay. This will ensure that they cannot be used together. 

High Beams
Provincial rules again, i have to have a high beam indicator on the dash, a simple blue led drilled into the gauge cluster should take care of it.

low beams
Provincial rules , i need to have day time running lights in the front. I think i will run the low beam filament all the time, then use the high beam 5th relay pole to disable the low beam filament so i don't run both at the same time. The low beam switch on the column would just turn on the tail lights and the side marker lights (another provincial requirement)

Side Markers
By law where i live 4 side marker lights are required. two in the front (amber) and 2 in the back (red). These have to light up with the high beams and the low beams. This should also include the license plate light. I can use 2 diodes, one off the high beams and one off the low beams to run this circuit.

License plate light
Triggered along with the low beams or high beams, Just wire this into the same circuit as the Side Marker lights. (see above)

Door Locks
I need a lock and unlock wire to ground out for the alarm system, may as well use it for the center console as well.

these are wired in to the PCM using 1 relay for each fan. I have located these relays next to the PCM in the engine bay.

This all goes directly back to the PCM, I need one additional wire for the brake signal to head back to the PCM to cancel cruise.

Reverse lights
Ign + run back to the switch on the trans, then to the reverse lights. I am also going to feed the switched signal back up to the dash. I can use this to flip on a rear view camera.

Acc +, 12v+, Speaker left door, Speaker right door, Amp wire to run behind passenger seat, RCA cables to run behind passenger seat, then one last set of speaker wire between the passenger and driver seats. The end result would be some kind of deck or computer in the dash, a small amp behind the passenger seat and a sub-woofer behind the driver seat.

Parking Lights
I still need to figure this out, are these separate filaments in the bulbs? Do Parking lights turn on the side markers as well?

Wiper Spray
No relay, straight from switch to the pump.

Wiper Speeds
factory harness straight from column to motor.

Power column
There are 2 wires that control the motor and another pair of wires that look like they go to a variable resistor. I was thinking about making a little box that takes Acc and 12v+, the resistor outputs, the switch inputs and the motor outputs. This would then make note of the columns distance when turning off the ignition and restore it when turning the ign back on. I could use a small Arduino that goes to sleep until it sees Acc come back on so it draws very little power. I think i will create the wiring harnesses now and leave them under the column and finish this project later.

Power Mirrors
I need a switch (i found some online but they are very expensive). I think a trip to the junkyard should turn up a small switch with a joystick and a switch that selects the left and right mirrors. For now i will extend all of the passenger side mirror wires over into the driver side door. All of the logic and control will end up in the driver side door.

Power Windows
The two wires on the window motor for the driver and passenger door will both run to the center console. These then wire into the FF window motor switches. I plan to add a window roll up module to the alarm at some point. This will roll the windows back up. The viper alarm system needs a wire for up and a wire for down, the module then wires in between the switch and the motor. I have to sit down and work this one out on paper.

The horn needs a relay according to what i have read. seems easy enough.

There is a wire on the vintage air unit to trigger the heater bypass to stop bypassing. This will feed to a small vacuum pump, that will trigger the unit i bought that will send hot coolant though the vintage air unit. I don't think i need a relay for this.

I think the right unit for me is the Viper 5904 2 way with remote start. This will need to wire into the lock/unlock, ignition, window motors, siren, horn.

Things i may still add

  • HDMI or other cable to run a camera mounted to the back. I would also need power for that camera and a trigger reverse wire to make the whole thing turn on.
  • Door poppers, hooked to the alarm
  • dome light switches on the doors + a dome light. I think the remote start needs this as well.
  • 12v Acc (lighter plug)

Do i have anything wrong? or am i missing something?


Wiring Work

I performed a little wiring harness surgery yesterday. I didn't have the original AC pressure switch connector as it sits on the opposite side of the large round connector on the engine harness and I no longer have that part of the harness. But good news, there is an identical connector on the engine harness with slightly different wire colors, also as a bonus if you use it the wire lengths are a perfect length to get from the factory GTM PCM location to the factory GTM pressure sensor location. The connector has a grey, black and brown wire. Grey and black match the old connector, the brown wire can be treated as if its red.

Here is how I removed the old pins from the old harness and moved them to the new harness

Step 1 remove the plastic colored plug end by inserting a small flat blade screwdriver into the left and right side of each colored plastic cap. Pull up on the colored cap at the same time. it will pop off.

Now remove the plastic cap from the back with the same small flat blade screwdriver. There are 6 plastic clips that need to be pried off, i found it was easiest to work on them in pairs from left to right popping them out one by one being careful not to let them pop back into place.

Now you can remove the pin by applying a slight amount of pressure to the latch and pushing the pin back through the connector (toward the wire side)

Now strip back all the old wire loom and tape and you will have a stand-alone harness

Apply new wire loom and heat shrink tubing to make it look like new.

I then took apart my new engine harness and pushed each wire into the correct pin.

I did the same for the AC request wire and AC trigger wire. Those two cables go from the PCM to the round connector as well. I took those wires and fed them into a new female weatherpac connector with some new wire loom. I will plug that female connector into a new male connector that will go though the tunnel toward the vintage air unit. I will place the relay and diode in the tunnel under right near the front of the engine. I started working on the diode and relay portion of the AC harness. I finished it but figured it was best to leave it out and double check all the wiring tomorrow.


Little more progress

I only had an hour to spare last night, so i managed to rivet in the fuse panel closeout and mount my engine harness fuses and relays to it. The FFR cold air kit will still have enough room to fit.

This is what all of the freshly riveted passenger side panels look like. 

With the little bit of time, i had left i predrilled 2 of the 4 driver side tunnel panels.

Tonight i only have an hour or so, but I should be able to figure out the C5 AC pressure switch and predrill the last 2 Tunnel panels.


I find myself still stumped with the AC wiring to the ECU.

i already have a fan override relay that will kick the fans on when i ground it out. What i need now is the PCM to disengage the compressors clutch above a certain RPM. I believe the PCM will also slightly increase idle while the AC is on. (not sure if that is true, i read it on a corvette forum)

I found the PCM pinouts for my factory C5 Corvette ECU.

As i mentioned (almost a year ago) in this thread these are the pins that i think i need.
C2 Pin 14 A/C Refrigerant Pressure Sensor Signal 
C2 Pin 17 A/C Request Signal 
C2 Pin 18 A/C Compressor clutch supply voltage

But it looks like these pins may also be involved.
C2 Pin 43 A/C Clutch relay control 
C1 Pin 45 A/C 5 volt reference for Refrigerant Pressure Sensor 

So here is what i am currently thinking.

  • There has to be a way to program the PCM to ignore the pressure Sensor, I shouldn't need it as i believe that the Trinary switch does this already. This means i can ignore C1 45 and C2 14
  • I believe the request to turn on the AC compressor should go to pin C2 17 (my guess is pulling this to 12 volts tells the PCM that we are requesting the compressor to turn on)
  • I believe the C2 43 grounds out when all of the conditions are positive and the AC clutch should be engaged. I think this should be fed into a relay that drives the clutch on the compressor, or maybe its goes high to 12 volts when conditions are met?
  • c2 Pin 18 could help drive that relay above but is not required, i could just pull IGN +12 instead.


Weekend GTM Work

I started off this weekend by mounting the passenger seat, I cut some triangle pieces of metal to give me something solid to bolt the seat to.

I welded the nut to the metal seat bracket so i can detach the seats easily without finding a way to get a wrench wedged under the seat

At this point i drained and pulled out the fuel tank and started to dry run the tunnel aluminum into place. This is where i rean into my first problem. With the aluminum in place the parking break wont move. It turned out that i had to remove the wire from the bottom of the boot so it would move easier, then bend the parking brake handle toward the passenger side.

gotta love clecos

painted the metal triangles that i had welded in.

I then riveted in the floor aluminum on both sides as it became evident that this piece has to be in before the tunnel aluminum.

I cut a piece of metal to fit in the factory fuse box location. I then tapped in holes to mount the fan relays, fan relays and engine harness relays. I then primed and painted the plate and the seat brackets.

I bought this on Aliexpress, it came today. It holds 8 relays and easily panel mounts. I will be using this for the lock/unlock, headlights, fog lights, hazard lights, etc.

I have had this tap and die set for years and finally got to use it. After welding on the nuts the bolts started to foul where the hit the metal brackets, Chased the threads and cut the last few and all was well.

my old makita grinder finally let out the magical smoke, so i went out and bought another one used for $60... was still in the box. Makita makes some solid tools, my last grinder was at least 20 years old.

Everything mocked up now (had to come off one more time for silicone. After this i removed all of the aluminum from the tunnel, made a wiring harness for the AC compressor complete with an ECU wire and put it all into split loom with heat shrink on the ends. I then attached both of the front mounted Vintage Air vent lines to the Vintage air unit. It was at this point that i noticed that the vintage air electrical unit on top was mounted so tight to the aluminum panel that the connectors would not fit.

Here you can see how i moved the Vintage Air electrical box. It was a pain in the *** to move as the screws were not not accessable. This one is on me, i should have noticed when i was mounting the foot box aluminum that i was blocking both the electrical connections and the mounting screws. I used a pair of needle nose channel locks to spin the screws out slowly from the top then bent the ends of the bracket out so i could mount it on the vertical aluminum on the passenger footwell. I also mounted a piece of rubber to the bottom of the control unit so it mounted tightly without it being able to vibrate when the car moves.

Time to hit the other side, i removed the driver seat, floor, gas tank, etc. I also had to move some wiring harnesses that i stupidly put though the frame where the aluminum needed to mount.

Before closing up the tunnel i drilled in 4 rivnuts and mounted the coolant lines as secure as possible.

This is where i stopped taking photos but i did get some more stuff completed.

  • I mounted the small piece of aluminum to the passenger side foot well at the top and sealed all the holes
  • mounted all of the tunnel aluminum with sealant and rivets
  • Riveted on the AC compressor cover.
  • Mounted the front aluminum piece that mounts beside the master cylinders

So here is my updated list

  • Mount the ODB2 connector by the steering wheel (to the square tubing between the console and the column
  • My engine harness has a fuse block of 5 fuses... needs a place to live under the dash.
  • move the fuel pump filter to make room for the dual FF cold air intake.
  • finish off the wiring and test it all out
  • Weld nuts to the drivers seat brackets + paint black (so i don't need two wrenches to remove the seats)
  • finish the tunnel aluminum
  • finish bolting AC accumulator together (pressure test it)
  • Add the drain line to the AC unit and route it out the bottom
  • Wrap the headers
  • cut the holes in the top aluminum for the AC vent ducts
  • put safety wire on the rear axle bolts again (removed a while ago to fix something)
  • Mount the horn
  • make a bracket to support the Kooks exhaust
  • install the fuel tank vents + roll over valves
  • Install the fuel pump controller

And here are the 4 items i finished after my 18 hours in the garage. 

  • mount the passenger seat (driver side required some welding, i will do the same to the other side)
  • rivet in the front piece of aluminum above the AC unit.
  • Add the small piece of aluminum in the top of the passenger foot well
  • make a metal plate to fill the factory fuse panel hole in the back. Then mount the fan fuses and relays to it

as i type this my fingers can barely move, drilling holes and putting in a few hundred rivets is really hard on the hands.

but i loved every minute of it.