Three Pin MBE ECU Cable How To

[aide]

Hi

I have the three pin ECU connection my car.

Which looks like this:


When I wanted to connect my laptop to the car I couldn't just buy a usb-to-rs232 cable and connect it up.

I actually needed an extra cable that had a female rs232 and a male three pin tvr ecu connector..

So I ended up making one - two actually

It was easy to put together. The hardest part was finding the three pin tvr ecu connector.
Which I did find for sale from a tvr parts shop, but they were a massive rip off for both the part and the postage imho.

So searched and found the RS Part for the Male Three Pin Connector:

And the Trident pins:


I then just got a bit of cable, some shrink-wrap, a female rs232 connector and housing from Maplin:


Soldered it together:

(Remember that GND on the rs232 pinout corresponds to the middle terminal on the three pin connector, the other two are Rx and Tx)

And ended up with this:


It's getting hard to buy this cable these days so I thought it would be a good idea to share the knowledge on how to make your own.

Best wishes
Aide

[Rufus Roughcut]

Clear and concise info Aide, top job

[Mr Cerbera]

... and works a treat.

Thanks !

[scotty_d]

I would have just cut the old connection off and fitted a 9 pin d sub connector. But a tidy job none the less.

[aide]

scotty_d said:

I would have just cut the old connection off and fitted a 9 pin d sub connector. But a tidy job none the less.

That would work scotty, bit of a bodge, but could be done.
Not sure if I'm getting old, but somehow I don't fancy lying upside-down in the passenger footwell with a head torch, a soldering iron, a d-sub connector and only 5cm of cable to work with.. [oh 5h1t, where did I put the solder!]

[gruffalo]

Aide, you don't fancy knocking a few up and flogging them do you?

[pmessling]

perhaps this should be made a sticky, not many sticky's on the cerbera side, and this is one of the questions that comes up often.

Especially as the search function doesn't always work.

[SimonKD]

Great guide Aide

Any chance of a pin out guide saying which pins of the 9 pin RS232 connector correspond to the 3 pins of the ECU connector?

Regards

Simon

[aide]

gruffalo said:

Aide, you don't fancy knocking a few up and flogging them do you?

Could do a batch of 10 perhaps. But it's a nice project to do at home yourself too!

[aide]

SimonKD said:

Great guide Aide

Any chance of a pin out guide saying which pins of the 9 pin RS232 connector correspond to the 3 pins of the ECU connector?

Regards

Simon

The three pin connector has GND, Tx and Rx.
Remembering that the middle of the 3 pin connector is Rx.
Off the top of my head:

3 Pin	RS232
Rx	Pin 2
GND	Pin 5
Tx	Pin 3

(I might have Rx and Tx mixed up - but as long as you have GND conneccted correctly, if you get Rx and Tx the wrong way around, it's fine, just swap them)

HTH
Aide

Edited by aide on Wednesday 22 April 20:51

[gruffalo]

aide said:

gruffalo said:

Aide, you don't fancy knocking a few up and flogging them do you?

Could do a batch of 10 perhaps. But it's a nice project to do at home yourself too!

I just thought that if you have left over connectors and pins you may wish to put them to good use.

[aide]

gruffalo said:

aide said:

gruffalo said:

Aide, you don't fancy knocking a few up and flogging them do you?

Could do a batch of 10 perhaps. But it's a nice project to do at home yourself too!

I just thought that if you have left over connectors and pins you may wish to put them to good use.

Ahh, I see what you mean. I think I have enough bits and bobs left to make another one.

[gruffalo]

If that is an offer then yes please Aide.

[aide]

gruffalo said:

If that is an offer then yes please Aide.

Will have a look and see what I have when I get home from the holidays..

[thefrog]

One of these from RS Components may avoid the need for a serial to usb converter cable altogether.

http://uk.rs-online.com/web/p/products/7158513/



I will order one soon and try it out.

[aide]

But that is a serial to usb converter?
Have to admit it's pretty neat.

ETA: are you going to just add a three pin connector to the end of the new cable? That would be a really nice alternative.

Edited by aide on Wednesday 6th August 14:55

[thefrog]

aide said:

But that is a serial to usb converter?

It is

aide said:

ETA: are you going to just add a three pin connector to the end of the new cable? That would be a really nice alternative.

Yup

[aide]

thefrog said:

aide said:

But that is a serial to usb converter?

It is

aide said:

ETA: are you going to just add a three pin connector to the end of the new cable? That would be a really nice alternative.

Yup

Nice one! it's certainly a neater alternative and you should make 10 as there are a few people, including myself, that would like one I'd say.

The crimp tool for the trident pins is a bit expensive - if you don't already have one let me know.

[thefrog]

I haven't placed the order yet, so if there are interested parties, I'd be willing to get a job lot and sort it out. I'll have ten of the three way connectors anyway since you can't order them in singles.

Crimping... yikes.... I thought they needed soldering... might have to rethink the above plan !

[aide]

thefrog said:

I haven't placed the order yet, so if there are interested parties, I'd be willing to get a job lot and sort it out. I'll have ten of the three way connectors anyway since you can't order them in singles.

Crimping... yikes.... I thought they needed soldering... might have to rethink the above plan !

yes, the trident pins need crimping (I also soldered them once they were crimped as well)
I'll post my crimp tool to you.

ETA: A piece of software I'm working on can only sense and use the Prolific chipset based USB to Serial converters.. I'm interested in one of these cables because it uses the FTDI chipset for it's USB to serial converter.

Edited by aide on Wednesday 6th August 18:06