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I'm in the process of getting ready to build a car PC running Linux. One of the features I'd really like to incorporate is the ability to record car statistics from the sensors live using ODB2.

Due to the location of where the ODB2 port is on my car (in the dash where the door opens), it'll be pretty difficult to close the door while the cable is plugged in. Therefore, I'd like to split the line further back a bit and route an ODB2 cable to the back of my car to the machine.

I've never done stuff like this before, but I have done a bit of electrical work (ie: switching out switches, plugs, rewiring things). I'm assuming that what I'd need to do would be to cut the existing cable and basically solder all of the internal wires together to both plugs, the one available in the door for mechanics, and the one running to the back for my computer.

Is this what I need to do? How can I put the wires back together again in a nice, insulated fashion?

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up vote 4 down vote accepted

I would recommend using inline wire splices. They are available at any auto parts store. Alternatively you can go the inexpensive and more compact (but more difficult) route. To be absolutely pedantic, NASA has a splicing guide, too. Some pictures follow.

Inline splices (option 1):


Manual wire joining (option 2):



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Those are called 3M ScothLok's no? – Cybergibbons May 8 '12 at 7:58
@Cybergibbons I have always used that term for these critters, but I may be wrong! These are used in telephony with small-gauge wires. cubus-adsl.dk/elteknik/billedopslag/scotchlok.jpg – Alex Hirzel May 8 '12 at 11:58
solutions.3m.co.uk/wps/portal/3M/en_GB/ElectricalMkts/… there are different ones for different applications. A butt splice is just an end to end crimp connector wiringproducts.com/contents/en-us/… – Cybergibbons May 8 '12 at 12:15
My only concern with these types of connectors, whatever they are called, is that they take up quite a lot of space. ODB2 is 16 pins, I think 12 are always connected, and you might be able to get away with 8. That's a lot of connectors in a small bundle of wires. – Cybergibbons May 8 '12 at 12:44
Depending on the make of the car, 3-4 wires may be all that are needed. Most inexpensive OBD2 readers only populate the pins they specifically need--this may be a practical way to see which pins are needed. Also, these connectors can be staggered in a harness. – Alex Hirzel May 8 '12 at 13:47

If you need to remove your temporary connection, a tap splice might be better.Quick Splice blade


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The actual problem to be solved is this:

*Due to the location of where the ODB2 port is on my car (in the dash where the door opens), it'll be pretty difficult to close the door while the cable is plugged in.

so the first thing to do is to see whether the OBD2 connector can simply be uninstalled and relocated such that the above problem goes away, without any cable splitting or tapping.

Since there can be only one OBD2 terminal connected at a time, you don't actually solve any problem by splitting the connector. This is strictly for the sake of providing an additional connector in another place, which will never be used at the same time as the original connector.

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