The Ultimate Guide to EFI Part 7 – wiring in the Haltech Elite 950

I reckon the #1 thing most car enthusiasts fear is delving into wiring. Most punters will have a crack at bodywork, but I’ve seen otherwise competent amateur mechanics run a mile from even simple wiring jobs.

I’ll happily admit I was thinking I’d do exactly the same when it came time to wire up the Haltech EFI set-up in my Pontiac. Thankfully, Haltech have many options for wiring, including plug-and-play engine looms to suit popular engines… which doesn’t include the old Pontiac V8 unfortunately.

Instead, I bought one of their Premium wiring harnesses which comes with a fuse box and clearly labelled wires that you match up to the beautifully simple wiring diagram to make the job a real walk in the park

After running the wires through the firewall and securing the rubber grommet against the firewall I ran out the wires in basic groups: ignition, fuel injectors, crank trigger, and accessories. This let me start breaking the job down into smaller sections that weren’t as daunting.

I used cable-ties to group the masses of wires into neat strands. I find keeping wiring neat and tidy at this stage helps prevent the job from feeling overwhelming and gives you back confidence.


The first wiring job I undertook was mounting and wiring the crank trigger. I purchased a hall effect sensor from Haltech, which came with a weather-proof Deutsch connector and instructions on how to wire it up to the crank trigger wiring in the Haltech 950 Premium wiring loom. 


The idea behind the sensor is you set cylinder #1 to top-dead-centre and then enter the firing order among other details into the ECU. The sensor reads the missing teeth on the trigger wheel and this helps the ECU correlate the engine’s position as it turns.


I am going to modify the bottom radiator hose to give more clearance to the back of the sensor as it currently rubs against the middle of the rubber. Haltech say it needs to be 0.5mm-1mm away from the trigger wheel.


While the ECU uses Deutsch connectors the FAST throttle bodies feature OEM-style “weather pack” connectors, also known as “pull to seat” connectors. These are commonly found on GM cars, which use Delphi sensors and wiring. This is the throttle position sensor (TPS) wiring plug.


Weather pack connectors use a different style of crimping tool compared to Deutsch (and other) plugs. The pliers on top are designed to properly crimp weather pack connectors and you can see the jaws are very different to the traditional ratcheting crimping pliers below.


A key difference to weather pack connectors is you need to feed the plug onto the terminated wires before you strip and crimp them. You then slide the plug over the crimps and they lock in – you cannot slide the plug over the crimps! In this pic you can see I have already wired up the intake air temp (IAT) sensor and am tackling the TPS as this means the throttle bodies are then wired up.


With the throttle body wiring sorted I was able to get to the next big job, which was sorting out how to wire the injectors. The Haltech Elite 950 allows sequential injection so there are 8 injector ground wires, with one power supply, so making it all neat, tidy but – most importantly – serviceable was difficult.


As my Pontiac never had injection I had to buy the plugs to fit all the sensors, injectors, coil packs and the like. The EV6 injector plugs came with terminated wiring so I ran each of the injector ground wires to the ground wire on the injectors to check their length and marry them up to the correct cylinder. 


I split the power wire between each bank and then piggybacked each injector in the two banks to that power source. The ECU provides constant power to the injectors and uses the ground wire to operate the correct injector at the correct point of the combustion cycle. I soldered these wires carefully, then covered them with heat-shrink. 


I had hoped to run the wiring under the intake manifold to make it neater but there wasn’t enough clearance to get the plugs between the valley pan and the intake easily.


The wiring tucks out of eyesight so I wrapped it with cloth tape to provide a resistance to arcing out or chafing on the intake manifold.


My first attempt at making a patch loom for the LS1 coil packs wasn’t successful. Incorrect gauge wire, bad crimps, bad wire routing lengths all added up to a messy job that was prone to failure. So, into the bin these went. Thankfully you’re only looking at approximately $50 worth of parts here.


I found a seller on eBay called Dirt Devil Industries (DDI) who sells pre-pinned coil plugs that came with a short terminated loom which allowed me to wire them how I wanted, so I purchased eight of these plugs and made my own patch looms to connect each bank of four coil packs to the wiring loom.


This allows me to easily remove the coil packs, service the wiring loom, or make removing the engine a little easier and simpler, as I just have to undo one six-pin Deutsch connector on each side of the motor. I still have to find a place to connect the ground wire, and find a way to integrate the ECU ground wire into the Haltech loom, but that should be simple (I will probably tee them in to the coolant temp sensor and TPS grounds)


The next steps are to mount and wire the coil packs, run the fuel pump wiring to the back of the car, wire the coolant temp sensor, mount and wire the 2-wire Bosch idle air control valve (IACV), wire the thermo fan, plumb the MAP sensor into the ECU, and mount and wire the oxygen sensor (o2 sensor) in the exhaust. Once they are all connected correctly I can hook up power to the ECU and start creating a base map for the 400ci engine to kick into life!

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