Connector considerations

[jharvey]

That connector GrowlingandBiffo posted has some pro's and cons. Looks like that half of the connector is about $10 and I'm assuming the other half is also $10, so about $20 for the folks that can't get them for free. I like the sealed and snap connection and I think it solves a number of problems that exist with connectors like the D sub connectors. That will prevent problems for many folks.

I'd like to avoid include having the power and signals together, routes too the edge of the board, sealed connector for all and pins that aren't rated for the current the carry.

Use of one connector for both power and signal increases the noise floor on your signal lines, and increases the chances of hard to predict problems. Ultimately increasing that voodoo portion of the install. It also makes it hard to shield the signal if you choose to.

Running the connector leads to the edge of the board, increase how often you need to cross over existing traces. This increases the desire for a 4 layer vs the preferred 2 layer board. Running the leads to the edge of the board may not allow the 2 layer design.

Some folks install the ECU in the cabin of the vehicle, or in a place that is already weather proofed. They don't have a need for the weather tight connectors, if you have a PCB mounted connector, they are limited to using that connector.

Also the pins look quite small. I'm guessing they are rated for around 1-5 amps. I believe a number of situations rely on higher current ratings, causing the need for multiple pins to be used. Using multiple pins can cause an unbalance current sharing. For example if you have a 10 amp need and you expect 5 amps per pin, but you have a small amount of corrosion, or resistance for any reason, (including RF spacing issues) you can share say 6 amps on one and 4 amps on the other. The injectors and coil packs are quite noisy with the inductive loads. If you use a single connector for these devices, you remove the possibility of uneven current sharing, tank circuits, and RF related issues. Keeping to a single pin vs multi pin, reduces the chance of many problems.

I see mouser has RJ45 and water tight RJ45 cable connectors. These watertight RJ45's are a bit more expensive, but they also allow for shielding your signal lines. Hmmm, might be worth thinking about for data lines. They are signal conditioned after all.

I think something like the AMP CPC (similar to mouser 571-2060361) connectors might be the best. I believe they snap lock, 17 signal lines cost about $2 each side for a total of about 4$, and power connection is about the same. For a total of call it about $10. They also offer sealed version of the same connector for a couple dollars more. Allowing you to choose if your a submarine, or a car.

I'm still looking into the differences in miniature, vs normal CPC, type of crimp tool, solder vs crimp, ect. However these guys are looking promising so far. Or at least I think they are.

[GrowlingandBiffo]

The simple rule here is what do the connector manufactures sell to the ECU manufactures....

They will have evaluated this many time, in fact connector manufactures are commissioned by ECU manufactures.

The Bosch 55pin connector is made by AMP.

If cost is a consideration use a second user ECU, and cut a foot of loom off, look closely at the the ECU and try to gauge how many time it has been plugged and unplugged.

To double check your choice ask a breakdown operator AA/RAC/AAA/Green Flag how many he has been out to where the connector was to blame...

You could even use the case it come in, to mount your PCB...

[Fred]

If cost is a consideration use a second user ECU, and cut a foot of loom off, look closely at the the ECU and try to gauge how many time it has been plugged and unplugged.

To double check your choice ask a breakdown operator AA/RAC/AAA/Green Flag how many he has been out to where the connector was to blame...

You could even use the case it come in, to mount your PCB...

Some people are definitely going to do this. Now that a custom PCB is 100% OK, I would say it will be commonplace :-)

Fred.

[Tony]

Some people are definitely going to do this. Now that a custom PCB is 100% OK, I would say it will be commonplace

Fred.

I agree for me anyway i would make an entire board specifically for my application using the stock ECU connector and if i run out of pins for specific I/O i will then add another connector to the board for this purpose .

I have found out the hard way that multiple wires jumpering from pin to pin and board to board is not the way to go eventually they WILL break at the solder joint as the solder wicks up the wire and cuses that to be a stress point, and if your luck is like mine it wont break while your at the shop where you can fix it it will be when your out enjoing you hard work then paying a tow guy to come bring you back home.LOL

The stock ECU connector is the way to go in my opionion for easy of instalation and trouble shooting ( assuming you have a good harness) plus when you need a new harness its not all that bad to surce a ready to go harness from a donor car to replace your existing bad one, it does take longer to figure out the signal wires and what does what in some of these factory harness but over all it SHOULD give the best reliability in the long run over rewiring a compleatly new harness unless you know exactly what you are doing.


Now for a custom insatall (IE: You car has a motor that never came in the model of car) then connectors dont really matter as long as they fit your requirements for you application.

Water proof connectors are nice indeed but for a car they are not totally neccesary unless you live in a wet climate where you car might draw alot of moisture then they would be something to consider now bikes,boats, ATV's,ect would for sure need a watertight connector unless you like cleaning connectors and pins everytime you get it wet and park it for a week marginal contact can be a bitch to track down sometimes and will make you want to smash ECU's with big hammer.LOL


I have not had anyproblems with the Dsub connector BUT they are designed for testing purposes and work fine for what they are they dont look very professional in my option and require alot of space for their size BUT by all means lots of people will use these and that should be fine use what you have and what you like because after all you will be the one fixing it if it breaks so just beacuse some one dosent like that piticular connector thats fine if Fred, and the others decides to use Dsub or AMP or spade connectors or whatever for the Base boards then thats fine atleast you can test to see what works and what dosent then go off of what works to make a new board to incorporate a sutiable connector for your liking.

I had not done any circuit building or board making till my first project and i learned ALOT on what works and what dosent it might look good on paper but once its done and working ( or not working ) then things change so be prepaired to go back to the drawing board a few times to touch some things up.LOL

[Fred]

Great post! :-)

The stock ECU connector is the way to go in my opionion for easy of instalation and trouble shooting ( assuming you have a good harness)

That is a fairly big assumption for many cars. The signal and grounding scheme on your board MUST match that of the wiring loom too. This one area where MS gives headaches. OEM looms are done the right way, and MS is done with the star ground on the board and not the head. That combined with the specific OEM wiring setups = noise issues. And no Bruce, it is not our fault...

Fred.

[Tony]

Yes Grounds are your freinds not your enimies when done right seperate grounds for high current ( injectors,relays,mosfets IGBT,ect) and ones for low current ( Processor and all 5V circuits) should be kept seperate as these will cause tons of problems down the road .

Gorunding is one of the most important part of any car and this is one thing that does need attention when considering adding a standalone ECU to the mix most stock harnesses have more than adiquite grounds ( after all they tested these things for tons of hours to find faults) and if the boards are done right they should work fine.

Another thing i have found out im my limited tseting is sometimes the factory 12V wire is not adiquite in the fact that SOME manufactures tend to run alot of stuff off the 12V wire going to the ECU some dont and this wouldnt apply but for those that do i would recomend a new 12V wired from a relay to the ecu coming straight from the battery the battery will help absorb some voltage spikes or drop ( to a point) and can help with tunning .

Example i wired my board off the STOCK 12V feed wired while logging i seen volatge spikes and dips in the 3-4 volt range by simply wiring it to a relay from the battery i now have a super stable 12v signal with no spikes at all come to find out the COP units and other items are tied on the SAME wire so of course there is spikes why they did this is beyond me but they chose to wire it like this from the factory and it worked fine for them but probably not the best way in my opinion.

[jharvey]

I have not had anyproblems with the Dsub connector

For those that like the Dsub, check out mouser 152-fm36w4p It allows multiple diameter pins intended for power, coax, ect, as well as a pile of normal pins. There is also mouser 152-fwa1ge a water tight Dsub housing.

I don't like these because of the lack of snapping. You can still have issues if you fail to penetrate fully.

[Fred]

You can still have issues if you fail to penetrate fully.

All this talk about penetration....

...makes me think of welding.

[Fred]

Bump for the connectors thread.

[jharvey]

Migrated from http://www.diyefi.org/forum/viewtopic.p ... &start=180

About the connector card, if we put the connector(s) on one edge of the board, the long side would likely fit 2 perhaps 3 connectors. I don't see much of a reason why you couldn't have one connector on one short edge, and a different connector on the other short edge. It would flip the EMS around 180 based on which you choose to use. If the bolt holes are symmetrical, then that won't change mounting it.

On a side note, I plotted the two copper layers, and it looks like I might be able to route the wires to the edge or near the edge of the board. From there the traces could then jump to the connector card. We don't have much room for a connector on this board, it might fit, but it's getting tight. Probably best to make the jump to the connector card.

Also, a quick count shows a total of about 54 pins. Some might be redundant, and technically not needed, others might be desired, so final pin count might be different.

Also, also, do we need one connector for them all? Perhaps one connector for DC power, one connector for injector power devices, and one connector for data? Just another thought.