In my experience, automotive electrical problems can be amongst the most frustrating to diagnose with loose or faulty connections often being the root cause. However, unlike so many other types of problems that can occur as a result of mechanical stress, driver error, or just plain bad luck, electrical problems can be almost entirely avoided by applying a little bit of knowhow when making connections.
Several years ago, I installed a fuel cell which – amongst other things – involved wiring up an electric fuel pump. For serviceability I incorporated a connector into the design, which involved splicing two wire ends together and applying solder to ensure they didn’t pull apart.
Everything worked well at first but after a while I started experiencing problems with the engine cutting out in the turns (one high speed bumpy turn in particular). My initial hunch was fuel delivery related – which ultimately proved to be true – but the specific cause was time consuming and difficult to diagnose. Random luck helped my find the problem sooner than would have otherwise taken.
While testing a new fuel pump in the workshop I bumped the connector and the pump sputtered. Turning my attention to the connector, I discovered that the soldered connection failed leaving me with two wire halves. The heat shrink insulating material hid the problem from view and kept them mostly in contact with each other but all it took was a little bit of force and/or vibration (like driving over a bumpy turn) to open up a gap breaking the flow of current to the pump.
Like most electrical problems, the fix for this problem was easy once diagnosed but a long an painful journey to get there. Ironically, in my effort to sure up the connection with solder I made it less reliable. Realizing this sparked my interest as to the correct way to make reliable electrical connections.
The topic of soldering versus crimping is often debated. Already, there have been several responses to this article denouncing crimping as the preferred method to soldering. That crimping is a preferred method is my opinion (a generalization for which exceptions apply) and I am in the good company of aerospace, military, Formula 1, and medical. If performed correctly, both soldering and crimping will produce reliable connections. Likewise, if performed incorrectly, both will result in unreliable connections. Hence, there is an abundance on anecdotal evidence for and against each method available on the Internet.
A key and significant advantage of crimping over soldering is the ease and speed with which a properly formed connection can be consistently performed. I have seen far too many people get soldering wrong (also my opinion, MSME & having worked in aerospace too) and hence my motivation for writing this article. With proper tooling crimping is nearly foolproof. There are a wide variety of connector types and associated tooling that range from inexpensive to very expensive, but even inexpensive connectors can produce good results. The tooling and connectors demonstrated in this article are on the more expensive end of the spectrum but the same principles and techniques apply to other connector types as well.
Why soldering is bad
Hopefully your answer to the above question is a resounding no. Ceramic has several properties that when viewed independently make it an excellent choice; however, its low ductility (brittleness) makes it a poor overall choice. Wire must be able to bend freely as it is routed through the car and is subject to constant flex and vibration. When you use solder to make electrical connections you’re also greatly reducing the wires ductility in the solder region and – like a chain – the wire is only as reliable as its weakest link.
If you take the opportunity to inspect the connections made by the manufacturer of your automobile, you’ll discover that most if not all connections do not have any solder applied. The recall cost to an automobile manufacturer for a flawed electrical connection can run hundreds of millions of dollars, so their engineers incorporate only the best practices for forming durable and reliable electrical connections. Think about this the next time you pull out your soldering gun to make your electrical connection super reliable!
The following video illustrates the effects of solder on a wire connection and compares it to a properly formed connection using a crimper.
Thus far the focus has been on reliability as reason to avoid solder but there are other practical considerations as well. Soldering can take significantly more time than crimping (a topic we will get to shortly). For large projects, this can mean added days. It also requires a higher degree of skill to execute properly if used (e.g., not enough heat, wicking past the contact into the insulated area, etc.). For enthusiasts, electrical work is often performed in compromising positions with poor lighting such as under the dashboard, underneath the car, inside the engine bay, etc., which can make applying solder a challenge. Proper ventilation in tight quarters can also be difficult to achieve but is necessary in order to avoid breathing in toxic fumes. Care should also be taken to avoid letting solder (or solder residue) come into contact with the mouth, cuts, and sores. Always wash your hands after handling solder!
I suspect many resort to soldering connections because they perceive crimps as being weak or otherwise insufficient by themselves. A common scenario it to take a crimp-style connector, crimp, and then apply solder to strengthen the connection. However, a properly executed crimp can be as strong as or stronger than the wire itself is properly executed. By adding solder you are ultimately undermining your desire to form a more reliable connection.
You might be wondering why soldering connections is bad when modern cars contain scores of electronic printed circuit boards (PCBs) each having hundreds of soldered connections. Unlike wires being routed throughout your car, the components soldered onto a PCB are not subject to flex and handling because they are mounted to a rigid plan (the PCB board) contained within an enclosure. If vibration is a concern, the PCB it can be mounted on vibration isolators and epoxy can further be used to mechanically secure the components in place. None of this is true for most automotive wiring projects. Furthermore, as with any rule, there are exceptions and the application of solder in forming connections is no exception. Used properly in conjunction with crimping, solder can be used to build a more reliable connection but is unnecessary in most cases and – in my opinion – the risk of getting it wrong does not outweigh the benefits and therefore is not discussed.
If done with care, solder can be applied to a crimp connection as an added measure of reliability by applying only in the area near the very tip of the wire. The solder must not flow into the region below the crimp compression as you want the wire itself to remain flexible so it does not break apart from the connector. In my opinion, the risk of making a mistake is far greater than any improvement in reliability (marginal at best). It also adds a significant amount of time for each connection to be made (2-3 times) and it therefore not advised.
The perception that crimping is inadequate may stem from the commonplace crimper available for about $10 at your local hardware, automotive, or electronics store. This tool has no place in forming automotive electrical connections and if used, adding solder probably will serve to better the connection.
The key to a reliable crimp connection is having the right tool for the job, and knowing how to use it. The right tool depends on the type of connector being used, of which there are many. Even an aerospace quality crimp tool will not work or produce proper results if used on the wrong connector type. Some shops limit themselves to using a small handful of connector types because they don’t want to or cannot afford to purchase tooling for every type. I’m partial to Deutsch DTM style connectors for reasons stated below and which will be illustrated extensively throughout this article. For these connectors, crimp tool like the one illustrated by Figure 5 is required. If you choose a different type of connector, be sure to ask the vendor or do your research as to the proper tooling required and learn how to use it properly.
Tooling and Connector Hardware
Deutsch DTM Connector
- Incorporates circular contact pins facilitating fast and virtually foolproof crimps.
- Wedgelock insert fixes pins precisely in place for smooth and easy plug / unplug action.
- Suitable range of wire sizes (16-22 AWG) for most connection needs.
- Available in 2, 3, 4, 6, 8, and 12 pin connector arrangements.
- Inline and flange mount available.
- Parts readily available from a wide range of suppliers in gold or nickel plated.
- Pins are easily removed from connector housing and can be purchased separately.
- Receptacle and plug assembly halves can be purchase separately.
I order my connectors through Motec USA because they’ve never failed me and they also offer kits that make ordering parts a little easier (housing, pins, and wedge sold packaged together). The kits can be found in the Motec catalog available on their website. For a complete list of distributors in the USA and worldwide, visit the TE distributors webpage. I found the complete Deutsch connector catalog on the LADD Industries website. LADD is a Deutsch distributor.
In addition to complete product line, the Deutsch catalog contains lots of useful information such as produce line overview, tooling, electrical characteristics, operating condition tolerances, and how-to instructions.
With the DTM connectors you can choose solid barrel or stamped pin types. I prefer the solid barrel pins because they result in fast and virtually foolproof crimps. This pins seen in the illustrations are the solid barrel type. Stamped pins have wings that curl onto the wire. Either pin type is fine for most applications. Just be aware there are two different types of pins, each requiring a different crimp tool. Refer to the Deutsch catalog for additional details.
For DTM connectors, I use the M22520/1-01 “large MilSpec crimper” manufactured by Astro Tool (Figure 5), also available from Daniels Manufacturing Corporation (DMC). These cost about US$250 new. You’ll also need to purchase a crimp head (a.k.a., “turret”), which is M22520/1-02 for the large crimper and about US$80 (Figure 9). In all, expect to pay about US$330 new. These are also commonly available on eBay for about ½ the cost, which is how I purchased mine. It sounds like a lot of money for a crimper, but its foolproof design will save you tons of time and you’ll get perfect crimps every time. I’ve used a number of different contact types and associated crimpers and this is by far my favorite, so I seek out connectors incorporating a solid round pin design for all of my wiring projects where applicable.
Like a quality crimper, you’re not going to find Tefzel wire at your local hardware, electronics, or automotive store. You’ll need to order it online but there are plenty of suppliers. I get mine from Pegasus Auto Racing Supplies.
For automotive use, always use stranded wire for flexibility. Solid core wire has no business being in an automobile.
As described in the illustrations below, I use the Ideal Stripmaster wire stripper. It’s expensive but only absolutely required if using Tefzel wire, else less expensive strippers of similar design can be used with good success.
The following steps are DTM connector specific and have nothing to do with crimping. They illustrate pin insertion and connector housing assembly. I’m using different wires (Tefzel insulated) crimped from a previous job so don’t be confused about why not red 24 gauge wires like the ones crimped above.
LADD is a Deutsch distributor.
Be sure to document your pin assignments and save them someplace safe.
About Feature Image
I just finished installing a Video VBOX Lite system in my car and am happy be driving my car again! It’s been 3 weeks since I started the project with 3-4 days of actual time spent. The biggest time sink was routing a microphone to the rear bumper which isn’t necessary but should make for a great sound track. I also lost a week to a wrong part being sent. If not for these two factors, install would have easily taken under a day.
Below is a video showing the output of my initial drive with the system recording just after completing the install, so minimal configuration. It’s not intended to be exciting (it’s not), but potentially informative for anybody considering a VBOX or evaluating similar systems.
VBOX is an in-car video and data acquisition system targeted at motorsports enthusiasts and racers who want to improve their driving by analyzing their driving after each session or event. I researched several different systems and opted for Racelogic’s Video VBOX system because it had most of the features I was looking for, was priced competitively, pre-sales support was responsive (which is a gauge for what I can expect post-sale), worldwide distributor network including two distributors in North America, good support site with monitored forums and regular updates, and an impressive product line.
The feature that attracted me to Video VBOX are:
- Multiple video inputs.
- Fully customizable video output.
- External stereo microphone input.
- CAN bus integration for getting at ECU data.
- High-resolution GPS and track mapping feature.
- Data stored to inexpensive, standardized SD card.
- Start/stop recording triggered by speed.
The one feature I wish VBOX had is HD video. There are other systems available with HD I opted for VBOX anyway because HD was a like-to-have for me, not must have. I purchased the VBOX lite, which is Racelogic’s least expensive system, as shown here:
I gave careful consideration to the installation prior to starting and opted as follows:
- VBOX stored inside glove box.
- 1-externally mounted microphone at rear of car (mono).
- 1-internally mounted microphone inside passenger cabin.
- 1 video extension cable routed back to roll bar.
- 1 CAN bus clip-on interface routed to driver-side foot well area.
- All other accessories, incl. power & GPS routed from glove box.
Layout schematic for all of the above is illustrated below.
VBOX Mounting Location
I considered two (2) locations for mounting the VBOX unit: Somewhere in the front trunk area and in the glove box. The biggest advantage of the front trunk is retaining full use of the glove box storage area, which the VBOX and all of its cabling pretty much fully occupy. However, I opted for the glove box for several reasons:
- Status LEDs able to be viewed without needing to get out of car.
- Easy access to record button if manual start / stop desired.
- No need to pop trunk to add / remove SD card.
- Easy to route cables in and out of glove box if needed.
- Close proximity to 12v power outlet (under dash).
- No need to route through wires through front bulkhead.
- Simply remove and store for safekeeping during offseason.
My overall goal was to minimize or eliminate need to make any modifications to the car in order to accommodate the system. By using the 12v power outlet I didn’t need to splice into any wires or tie into the fuse box. Racelogic also makes a clip-on interface that reads signals off of the CAN wires without needing to splice into them so I went this route as well. (More on the CAN interface below.)
The VBOX has a stereo microphone input and includes a splitter and two single channel condenser microphones so that left and right channels can be picked up at different points. I ran wires for mounting as follows:
- Inside cabin facing driver to pick up conversation and sounds hear by driver such as tires working. Also hoping that by pointing at driver from dash, wind buffeting will be kept to a minimum.
- External to car and hidden behind rear license plate facing downward. Not coincidentally, this also happens to be right over the exhaust tips.
I expect (hope) that this should make for some great audio tracks. Will probably require lowering exhaust channel level relative to cabin channel during editing in order to get a good balance.
My system accepts 2 camera inputs (more expensive models accept up to 4). Both are mounted from inside the vehicle:
- A high-resolution camera is attached to the windshield using a suction mount and faces forward across the hood of the car. This will provide an unobstructed view of the track and is the main video displayed.
- A low resolution camera is attached to the roll bar aiming at the driver from behind. This will be shown as an video inlay (picture-in-picture) and will be useful for accessing factors such as driver smoothness.
CAN bus signals are captured using Racelogic’s clip-on interface. This is nice for at least three (3) reasons:
- No need to alter the cars wiring harness.
- I was fairly confident I had the wires but not 100%. With the clip-on interface, no need to worry about hacking-up the electrical in search of the correct pair. Fortunately I got it right the first time thanks in-part to some thoughtful Internet posts.
- Non-physical interface for measuring signals means no chance of measurement affecting the signal and possibly causing CAN bus errors, which could in-turn affect vehicle operation.
The most obvious place to hook into the CAN signal was near the ECU since the pin-out schematic clearly identifies high and low CAN signals. However, it can also be picked-up of these same wires as they route up through the drivers foot well area near the fuse box. I opted for the latter because in the event of issues down the road, less stuff to need to tear into to diagnose and repair. (I apply this philosophy to all wire placement and routing considerations.)
The CAN bus interface is shown in the figure below and will be discussed in more detail with installation.
The bulk of the work involved with the install involved routing a microphone to the rear of the car. It’s a lot of work for just one (1) cable, but worth the effort in my opinion because it’ll return glorious audio tracks as opposed to the all too common wind-buffeting filled tracks heard on the Internet.
This is not a step-by-step guide so I’m only showing the basic flow. If you want to follow similar approach for your specific car, you can get detailed disassembly instructions on the Internet. Installing on a 2011 Porsche 911 GT3RS (997.2) and there was ample amounts of information on forums like Rennlist and Renntech that detailed anything I needed to know. For any Porsche 997 owners reading this, I’ll provide any 997 specific details that are not already amply posted about such as center console removal DIY.
CAN bus interface
A CAN interface is optional. Without it you’ll get the basics like video, audio, vehicle speed, g-forces, track mapping, lap timing. With it you can get a whole lot more data. What you get depends on your car. For my car (997.2 Porsche), I can get at:
- Lights on / off
- Reverse engagement
- Engine RPM
- Throttle position
- Parking brake engagement
- Road speed
- Brake position
- Steering direction
- Steering angle
- Wheel speed (RR)
- Wheel speed (RL)
- Wheel speed (FR)
- Wheel speed (FL)
- Clutch engagement
- Water temperature 1
- Water temperature 2
- Oil pressure
- Oil temperature
- Boost (my car is NA so does not apply)
- Gear selection
The VBOX lite only allows up to 4 CAN channels at a time, with the option to purchase up to 4 more for a total of 8 (purchased individually). I’m going to start with throttle position, steering angle, brake position, and gear selection. I’ll probably also purchase 1 extra for oil pressure.
With the VBOX unit you can get an unterminated CAN cable and wire directly into your system. But they also sell a clip-on interface that eliminates the need for splicing. It also guards against the VBOX system incidentally introducing any CAN signals onto your system’s CAN bus. I opted for the clip-on interface.
CAN bus clip-on interface and installation
If you’re using the CAN bus clip-on interface or if you have a Porsche 997 you may find this section useful if interfacing with your vehicle’s CAN bus.
The clip-on interface came with no instructions and it was immediately ambiguous to me regarding how to position the wires. The correct way in my non-humble opinion is to position the wires so that the surface area labeled CAN_H comes into contact with the CAN high wire when the shell halves are snapped together. However, some companies in an effort to make things easier for people outsmart themselves and just end-up making things more confusing. So I wondered did they mean for the upper half to read like a map for positioning the wires into the bottom as viewed during installation? Certainly, I’m thinking too hard about this but I did some checking after finding no documentation online and came across the promotion video for the interface showing the latter (reads like a map). Turns out the promotion video gets it wrong. (For BMW, which is the car used, CAN high is red-blue, and CAN low is red).
I contacted Racelogic support for clarification and they responded as follows (option1 is having the CAN high wire in contact with the surface area labeled CAN_H):
As for the ambiguity issue you are correct in thinking option 1 is correct. As we have had this question before I have contacted the developers of this and they are aware of this issue and are working on a new version that can be used either way round. Although we will have to make do with sticking to option 1 for now.
Also my opinion, I think they could save themselves some engineering investment and simply include a small piece of paper with the clip-on interface showing proper usage since it’s otherwise self-explanatory.
Also complicating my install was that VBOX sent me a clip-in interface for one of their higher-end (not VBOX Lite) which accepts a different style connector. Shown below is the other end of the cable for the interface I received, where as it should look like a PS2 connector from the outside. This added 1 week to my install while I waited on the part because it needed to be shipped from the UK. (Would have been longer if I didn’t foot the bill for overnight express which VBOXUSA was unwilling to do, so make sure you emphasize having them fulfill the order correctly for your system if ordering a VBOX CAN interface.)
Setup and Configuration
I’ve only just started to play with configuring my VBOX system. Except for reading the CAN data, everything was plug-and-play simple. Getting to where I could read the CAN data for my car took a little help from VBOX. Not getting anything at first begged the question if installation error or software configuration issue. I was very confident I had correct CAN wires and support clarified proper usage of the clip-on interface so either an issue with the clip-on interface itself or software configuration was my thought.
The issue turned out to be software configuration. VBOXUSA sent me a scene file for my car which had VBOX reading the CAN data; something I was unable to do using the CAN database file for the 997.2 Porsche. Different cars differ in how they use CAN to send data so you need model specific information which VBOX provides via their online vehicle CAN database. The database returns a file that gets read into the scene file loaded onto the VBOX telling it how to interpret the CAN signals.
The only other thing I needed to do to get the system ready for my initial (and successful) road test was aim the cameras. I purchased a small display that plugs into the AUX port on the VBOX and shows video in read-time. This makes setting up the cameras super easy. Just hold display in hand while adjusting each camera to desired position. The following figure is a photograph of the display screen:
Video showing trial run of system. This is with only minimal configuration so only minimal data is displayed and the brake pressure gauge needs reconfiguration. Goal of this drive was to simply check out video quality, confirm GPS working, etc. Just the basics.