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Practical Wiring - Club Level: Component Inspection and Physical Mounting

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Component Inspection and Physical Mounting

07.15

Component Listing, save a local copy to be able to edit.

00:00 - In this section of the course we will discuss the key design techniques required to build a robust and reliable performance automotive wiring harness.
00:08 Our wiring harness design process has several overall goals.
00:12 We need to ensure that we supply 12 volt power to all parts of the EFI system that require it at the correct time.
00:19 We need to ensure that the ECU is correctly wired to the EFI system sensors so it can interpret the signals it receives from these sensors.
00:26 We also need to ensure that the ECU can control the EFI system actuators, in order to control the running of the engine.
00:34 Physically we need to design how the harness is routed throughout the engine bay and interior as we want this to have a tidy appearance and avoid unecessary strain being placed on the harness.
00:45 The design techniques we will discuss now form the key knowledge required to accomplish these goals.
00:51 We'll look at them in detail and run through a few examples, as a thorough understanding of these concepts will be critical when we bring them all together into the HPA eight step process in the worked example section of the course.
01:02 A small warning here, the design process can be a slightly dry and lengthy one to go through, but it is completely critical that it's completed before the first length of wire is cut as it's much easier to find a potential issue now and correct it before the physical construction process begins.
01:18 The first step we will undertake is to list out on a document all of the components of the EFI system.
01:23 That is all of the controllers, sensors, and actuators our wiring harness will need to connect to.
01:29 Some of these components will be obvious and common to almost every EFI system you're building a wiring harness for.
01:35 A standalone ECU, injectors, ignition coils and fuel pump for example.
01:39 But some may be less obvious or only found on some EFI systems.
01:43 Such as idle control valves, boost control solenoids, or variable cam control solenoids.
01:48 This step can be closely tied to the overall design of the EFI system and is best undertaken alongside the person that will be tuning the engine.
01:56 As mentioned, this course does not cover EFI system design, but if you'd like to know more on that topic, our EFI tuning fundamentals and practical tuning courses are a great place to start.
02:06 There is a link below to a component listing document for our example vehicle, an FD3S Mazda RX-7.
02:12 This basic document will allow us to confirm that no parts of the system are missed and will form the basis of our wiring connection document to be prepared later.
02:22 Once we have all of the components of our EFI system confirmed, we need to determine where they are physically mounted in the vehicle.
02:28 For items like sensors and actuators, these will typically be mounted in the original factory location or very close to it.
02:34 But for items we're adding like the ECU and power supply relays, some work will need to be done to physically mount them in the vehicle.
02:41 In the majority of street car installations, we will be replacing the factory ECU and this gives us a great location for fitting our standalone ECU and power supply components.
02:51 In many instances, it can even be advantageous to reuse the existing power supply wiring in the vehicle, if it's compatible with our standalone ECU.
03:00 In the case of a club level race car, where much of the factory wiring and interior will likely have been removed, I tend to favour mounting the ECU at the top of the firewall above the passenger footwell or on top of the transmission tunnel close to the firewall.
03:12 As the majority of the wires in our harness connect to the ECU, these central locations can make harness construction and planning much easier.
03:20 While keeping the sensitive electronics safe from moisture that may collect on the floor.
03:25 An important consideration, particularly relevant to ECU mounting, is the angle at which the wires and connectors meet our system components.
03:32 For an OEM mounting location, this typically will not be an issue as they will have been placed to allow connection and disconnection of the original harness.
03:40 But when we're deciding upon a mounting location for a component, we need to make sure that connection and disconnection is possible, and there is clearance for the wires as they exit the connector.
03:49 As an example, when wiring to a device that uses an AMP superseal 1.0 connector like our Link Fury ECU here, I like to leave at least 50 millimetres of clear space behind the connector to ensure that servicing is easy and quick.
04:04 It's very important that at this stage we finalise the mounting locations of our components, as any changes that need to be made once harness construction process has begun, will require a lot of rework.
04:15 We can see in the engine bay of our RX-7 here, the OEM locations of the engine sensors and actuators have mostly been retained.
04:21 With a planned conversion to a single turbo allowing us to remove most of the original twin turbo control solenoids.
04:28 We will be replacing the original ignition coils with individually internally ignited coils and much of the emissions related equipment has also been blanked off.
04:37 We will be adding fuel pressure and engine oil pressure sensors, as they are critical parameters that we would like the ECU to be able to keep an eye on.
04:44 Finally an aftermarket boost control solenoid will be installed to replace the unreliable factory item.
04:50 Our standalone ECU has been mounted on the same location as the original ECU with clearance for the connectors confirmed.
04:57 There is also space behind this kick panel for our additional power supply relays, keeping them tidily mounted and out of sight, allowing our interior to retain a nice original look.
05:06 The last step of the component inspection and physical mounting process is to identify the connectors required to connect the wiring harness to the EFI system components.
05:15 When we're using factory sensors and actuators, we can sometimes reuse the connector bodies from the original wiring harness, provided they're still in good condition and can be easily repinned.
05:25 Unfortunately this is often not the case as they will have become brittle and cracked over many years of heat cycles.
05:32 Whether we can reuse the original connector bodies or not, we still need to identify them.
05:36 As at the very least, we will need to source new pins for them to crimp onto our new harness, or if the body needs to be replaced, we will need to know the part number to source.
05:45 This step often requires a lot of internet based research and browsing of connector catalogs.
05:50 With a bit of experience you will get to know the common features of the various brands and be able to identify the connectors much quicker.
05:56 We'll have a look at an example now, being the throttle position sensor connector on our RX-7 example car.
06:02 We're at a little bit of a disadvantage here as the connector is missing from the factory wiring harness, so we're going to have to do some work on the internet to try and track down the connector we're going to need.
06:11 A quick Google for FD3S TPS connector brings up quite a few images of a grey four pin connector body with a prominent orange locking insert.
06:21 That orange locking insert is a telling sign in this instance as it's indicative of a Sumitomo DL series connector.
06:28 A quick comparison between the picture of this connector and our TPS housing, confirms that the key ways are in the correct position and this will be the correct connector for our application.
06:38 This information is added to our component listing document as it will be required when we prepare our wiring connection document later on.
06:46 If the EFI system component we're making a connection to is from an aftermarket supplier, such as our standalone ECU, or higher flowing fuel injectors, then the connector required will either be supplied with the item, or documented to make tracking it down much easier.