Category Archives: Electrical

Electrical

Wiring an ECOTEC engine

Leave a reply

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

4 Replies

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.