Category Archives: Wiring

Electrical wiring, relays, fusebox

Wiring Up the Gauges…

Moving along on the wiring, albeit slow.  Today, I spent 6 hours working on wiring up the instruments.  I was able to re-use some of the looms I made up the firs time, but had to make plenty of alterations along the way.  This is what it looks like from the backside:

The gauges are VDO Vision.  The have been great and are all electronic, compatible with the ECOTEC.  The speedo is programmable, so it is 100% dead nuts accurate.  The backing plate is aluminium and the front is made from quilted maple (I’ll have pics of the front in a later installment, once the dash is in place).

I realize this looks perhaps, unimpressive – but a huge amount of work has gone into making this up.  Every single connector has been soldered and shrink wrapped.  Since I wanted to make this so it can be removed easily, every circuit is connected to a “Weatherpack” connector.  This is why it has taken so long to make.

The following picture shows the dash area in bowtie6 before the dash goes in.

So…  What do we have here?

  • The heater has been replaced with an aftermarket unit.  The “original” heater unit I used to have developed a leak.  A little research found the unit pictured above which was a) cheaper and b) more efficient.  Plus it is able to withstand higher pressure.  This is desirable since it allows a high PSI cap on the radiator.
  • The transmission tunnel has been made from scratch to match the ECOTEC’s AISIN 5 speed gearbox.  It will be covered soon in Dynamat Extreme, just like the rest of bowtie6 has.
  • Finally, the piece de resistance:  If you look close, you can see the steering column is now fully adjustable.  Yes, a special mechanism has been made by my cousin Jim that allows the column to tilt with the flick of an adjustment bar.  I’ll have more on this later, once I get it all bolted back together.  Trick, huh?

This wiring effort has been very time consuming, but the end result will be fantastic.  There is a huge satisfaction from wiring up a car from scratch.  Not many people can do this type of work – it takes patience, but it sure is a lot of fun.


bowtie6 Wiring – Part II –

Engine wiring is progressing right along,  albeit slow.  This part of building a car takes time!

So far the engine harness is complete.  All wires to the ECM have been accounted for and the main looms have been covered with crinkle tubing.  This tubing protects all wires and keeps things looking neat and professional.

Another engine bay picture showing the fuse box on the left, the coolant overflow tank, coolant lines and brake master cylinder and hydraulic clutch reservoir.  The coolant expansion tank is all hand made aluminium.  Missing from the coolant expansion tank is a small rubber hose going to an overflow tank behind the radiator; also hand made aluminium.  And yes, all the rubber coolant hoses are missing their clamps.  Just haven’t had a chance to get there yet!

Below, is a close up of the new fusebox.  On the bottom left, you see the new fuse box.  This is where all the relays, circuit breakers and fuses that control the engine compartment reside.  This is what it looks like:

So what do we have here?

Starting from the bottom:  below the box, hidden from view is a post that goes through the firewall.  This post is insulated with a Bakelite insulator.  From this post, wires feed battery power to the circuit breakers.  There are a total of seven circuit breakers; one for each relay.

Above the circuit breakers there are seven relays.  They are used as follows:

  1. Horn relay
  2. Electric Fan relay
  3. Headlight “on” relay
  4. Headlight high/low relay
  5. Starter relay
  6. Ignition relay
  7. Start button relay

Finally above all this are two banks of fuses.  To the left of the fuses is the electric fan controller and below that, the engine’s ECM.

Why so many relays?  The idea here is to use a relay for each device that requires high current, for example the electric engine fan.  The idea is to let the switches run low current controlling the electromagnet in each relay.

I know what you are going to say:  where are the turn signals and parking lights?  Yes, they have been left out.  Not by mistake, but by design.  Underneath the dash will be a smaller fuse box, containing fuses and four relays.  This is the part I’m working on now, and will be featured in the next installment…  Stay tuned.

bowtie6 Wiring – Part I –

Making a custom wiring harness is an interesting process.  It takes time and careful thought.  Is it for everyone?  No.  This is the second time I’ve wired bowtie6 and this time, I’ve applied several lessons learned from the first time.  Basically:  make things as easy as possible.

I’ve written previously about all this but I thought it would be nice to give a more in-depth view of the work I’ve done.  Maybe this might be of help for someone, so let me start with the engine.

To start with, a factory GM engine harness was sourced.  Contrary to popular belief, one does not need to buy a special harness (they are usually very expensive) to make an EFI engine run.  When properly modified a factory harness is an excellent starting point:  all the sensor plugs are there and the wire is of excellent quality.  Special care has to be taken however, when the harness is extracted from the donor car:  you want to make sure you get all the plugs and pigtails, including the fly-by-wire throttle pedal and its wiring pigtail.

I’ve seen many conversions where folks take an original harness and along with that, the instrument cluster, fuse box, firewall connectors, steering, etc.  This results in a cobbled up, complicated affair.  Why?

  • The donor car’s instrument cluster is kept because modern EFI will not get along with original, mechanical instruments.
  • The steering column is re-used because of the special vehicle anti-theft device that depends on the special tumbler and key to make the engine run.  This is commonly known as VATS – Vehicle Anti Theft System.
  • The original engine fuse box is retained because it is already made and it just “works”.

There is a better way.  In my case, the harness was sourced from an Ecotec powered vehicle: a Chevy HHR.  With the aid of the factory service manual for the Solstice/Sky, the harness was simplified by removing unnecessary circuits.  Many wires were shortened and by doing this the harness was greatly simplified and made to fit the engine bay of the TR6.  I did this because again, I’ve seen many conversions where people don’t resize the harness and this gives the engine compartment a very cluttered, busy look.  I’ve also seen conversions where great care has been taken to hide as much of the harness as possible.  This gives the installation a very professional, “factory” look which is not easy to do but if you take your time makes a huge difference.

In the case of the older six and eight cylinder engines the VATS can be disabled by adding a small, inexpensive aftermarket module or by having the ECM modified.  This solves the problem of having to use the original key, tumbler and steering column.  With the previous V6 in bowtie6, I used the aftermarket module.  It basically had a switched hot lead, a ground wire and a wire that was in turn spliced into a pin on the ECM.  With the Ecotec, we did not use a module instead we used software running on a laptop to disable the VATS circuit.

The ECM came from the same donor HHR the harness came from.  This gives a good starting point and is compatible with all the sensors, fly-by-wire throttle, etc of the “original” vehicle.  In my case, I’m running the 5 speed gearbox as fitted to the Solstice/Sky therefore the separate computer used to run the electronic automatic gearbox is removed – this was part of that “simplification” of the harness I mentioned previously.

After all the work of checking every wire for continuity, removing unnecessary wires and length alterations, several loose wires were left:

  • There is one unswitched hot lead that keeps the ECM alive.
  • There are a number of switched hot leads.  These control items such as the O2 sensor, injectors, coils, etc.
  • There are a number of ground wires that must be tied back to either the engine and consequently the engine must be grounded too..
  • The ECM controls the fuel pump.  Therefore there is a wire from the ECM that eventually goes to a relay that energizes the pump.

This pretty much wraps up the engine harness.  All this has been done so basically bowtie6‘s Ecotec is all wired up.  Not for the faint of heart, this process alone has taken many hours to accomplish.  There is not easy way out here, but the result is very cool indeed.

So what is left to do?  I’ve taken a different approach this time.  The first time I wired bowtie6, there was one central fusebox where all circuits originated from.  This was fine and dandy.  The fuse box was hidden behind the dash but the problem was twofold: 1) a huge amount of wires coming and going and 2) it was extremely hard to get to.  I once had a fuse blow and it was a hell of a job to find the blown fuse.

This time, the new harness is simpler and has been broken down into three main sections:

  1. Engine compartment:  this section will hold the main circuits managing the engine harness.  I’ve also included the headlights, horn and electric engine fan circuits.
  2. Occupant’s compartment:  basically inside the car.  A separate smaller fuse box will control all switches, instruments and heater.
  3. Trunk compartment:  the last small fuse box where the tail lights, reverse lights, fuel pump and fuel sending unit are all controlled.

In the next installment I’ll have more details about the engine compartment wiring which has been completed.  Stay tuned…

Wiring an ECOTEC engine

This Memorial Day weekend has been very busy and a great deal of progress has been accomplished with bowtie6‘s new engine harness.  Why all this effort?

The donor harness came from an HHR with a 2.4 Ecotec.  Obviously, the ECM on the HHR is located in a completely different location.  This means the harness is very long in some places and very short in others.  Very few circuits are “just right”, so quite a bit of work has to go into making alterations.  Basically, every sensor circuit to be modified has to be cut, soldered and shrink wrapped in order to maintain 100% integrity.  This takes time.

I guess this is taking things to the extreme but these are the details that differentiate amateur, shade-tree “swaps” from a 1st class, professional installation.  The goal is to make the the engine harness disappear and this is not easy to do.

The picture above shows the ECM resting on the passenger’s side of the engine compartment.  The ECM will have a new special made enclosure, including relays, fuses and circuit breakers.  Again, it takes time but the results will be pretty impressive.

From the ECM, the harness has been divided into two separate looms:  on the driver’s side is the knock sensor, crankshaft position sensor, rear cam sensors, alternator, injectors and throttle body.  The passenger’s side loom feeds the coilpacks, O2 sensor, temp sensor, mass airflow sensor and forward cam sensors.  Looks simple but there has been a lot of work into this!

Next to do will be to build the new ECM enclosure and start wiring relays, fuses and circuit breakers.  This will tie all the switched hot leads as well as constant hot feed into the ECM.  Finally all grounds need to be resolved.

Finally, the full exhaust system has been put together.  The bespoke stainless headers have been permanently bolted to the block and the exhaust pipe bolted on.  More on all this next time – it is quite stunning!


Wiring Harness

Tonight I started working on the engine wiring harness.  Doing an engine swap requires some sort of engine harness to be used along with the computer (ECM) in order to make the engine work.  This is the part where “old school” hot-rodders shudder and panic about.  This is also the part the trips up many folks attempting to run electronic fuel injection (EFI).

I’ve worked with my cousin Jim for the past 15 years perfecting the fine art of transforming a stock wiring harness into something that can be used to fully run a modern EFI engine in a classic car.  At first we worked on “throttle body” engines – basically a glorified carburetor but with the advantage of electronics.  These were the early EFI setups that offered much better economy than a plain carburetor but had a long way to go.  Throttle bodies evolved into individual injectors feeding each cylinder and more sophisticated ECM’s.

Through the years, we were able to adapt the L98 Tuned Port v8 with it’s distinctive intake with eight runners going to each cylinder.  As the L98’s became scarce we moved to LT1’s and LT4’s.  During this time, we also mastered the L32 V6 as originally fitted to bowtie6.  The next step was the LSx family of engines.  Currently we’ve focused on the ECOTEC engine as fitted in Jim’s TR4 and now my TR6.

The throttle body harnesses were the simplest.  No much really to figure out.  When we started using L98’s and LTx’s in Jaguar XJ6 and XJS conversions, at first we sourced the harnesses.  They were not cheap, so we took a stab at using original GM harnesses and cleaning them up.  If done properly they make an excellent harness however it takes some effort to figure them out.

This photo shows the harness from a wrecked 2.4 ECOTEC powered HHR.  The harness is basically all there; however it must be modified to work with the ECM and placement in the engine fitted to bowtie6.  This photo shows the harness after I had removed all the plastic casings protecting the harness.  This is done for several reason, among them exposing all circuits and it is easier to trace the wires to decide what needs removal.

We don’t use the original GM fusebox.  We also remove redundant ground wires and hot feeds, thus allowing the harness to be much simpler and easier to deal with.  Depending on what donor harness you use, certain pinouts on the ECM connectors must be relocated.  This is all done by using original GM Factory Service Manuals.

I’ll have more as the process takes shape.  This is actually a lot of fun however it is a little time consuming.  At the end of the day, it is a very rewarding feeling when the harness allows the engine to run.