Wiring Fundamentals: Testing
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Testing
04.31
| 00:00 | - Much like the documentation section at the beginning of the harness construction, bench testing our harness once complete, can be a relatively tedious process, but also a completely necessary one. |
| 00:11 | At the professional motorsport level, a testing rig would be constructed to which the harness is plugged into. |
| 00:16 | This rig can test both that every pin is connected to where it should be, and that it is connected to only where it should be. |
| 00:23 | This is the hard part of bench testing our harness, as although it's a relatively straightforward process using the continuity setting on our multimeter to test each pin is connected to its required destinations, testing that it is only connected to its required destinations and nowhere else is much more difficult. |
| 00:40 | For our example RX-7 race car wiring harness, there are approximately 150 individual pins. |
| 00:47 | To completely test every combination of connections between them would require several thousand tests. |
| 00:53 | While a testing rig can do this very quickly, it's not something we're going to do by hand with a multimeter. |
| 00:58 | Instead we use our multimeter on the continuity setting to determine that each pin is connected to its required destination. |
| 01:05 | We then test the power supply and grounding systems with the harness installed in the vehicle, connected to the battery and ground locations, but with the electronic components unplugged. |
| 01:14 | We can then turn on and off our driver controlled switches and confirm that our power supply system is providing 12 volt power to the pins that need it at the right time and our fuses are remaining intact. |
| 01:26 | We then continuity check between the remaining pins and ground to confirm that there is a ground connection where needed but no other pins are short circuited to ground. |
| 01:35 | This minimises the risk of an undetected error causing any damage to the electronic components when they are connected for this first time. |
| 01:42 | Testing the power supply and grounding stages of our harness construction is covered in the practical wiring harness construction course. |
| 01:49 | But I will show the continuity testing method now on our example injector harness section. |
| 01:54 | So the first thing we need to do is turn our multimeter to its continuity test setting. |
| 01:59 | And we then need to refer to our documentation. |
| 02:03 | So we can see from our documentation that pin one of all of our injector connectors is connected to pin one of our interface connector. |
| 02:12 | So this is the 12 volt supply circuit to the injectors. |
| 02:15 | So using our multimeter we can test that. |
| 02:18 | On the back of our DTM six way connector the pin locations are numbered. |
| 02:23 | So if we find pin number one, I can insert my multimeter probe into that. |
| 02:28 | And then I can test pin one on this injector connector and if it makes a connection we should hear the multimeter beep. |
| 02:38 | So that's successful, I'll go through and test the rest of these injector connectors now. |
| 02:54 | Excellent so with those tested we know that pin one of our interface connector is making a connection to pin one of all of our injector connectors. |
| 03:02 | So the 12 volt power supply circuit should function as intended. |
| 03:05 | Now from this point we refer to our documentation again. |
| 03:08 | And we can actually mark off that we have tested all these connections. |
| 03:14 | That way we can easily keep track of where we're up to and we won't lose our place. |
| 03:19 | So looking at our documentation again, we need to test the remaining four connections and we can see that on our front primary injector, pin number two should connect to a injector interface on pin number five. |
| 03:31 | So we'll go ahead and test that now. |
| 03:34 | So once again on the back of our DTM connector we can find pin number five, and insert our probe in there. |
| 03:42 | And because we've labelled our harness, finding the front primary injector should be pretty easy. |
| 03:50 | Which is this one here. |
| 03:51 | And we can test that connection. |
| 03:58 | Excellent so we know that's connected up in the correct place and should function as we intended. |
| 04:02 | I'll go through and test the rest of those now. |
| 04:11 | So with all of our connections ticked off we can be sure that each pin is reaching its required destination. |
| 04:16 | Now while this testing method is not absolutely complete, it is achievable quickly in the field and will catch the large majority of errors, almost certainly those that would cause permanent damage to components. |
