Later ECU Cable/Connector

[Demondad]

I've got an old laptop with the diagnostic software but no cable. Just wondering before I shell out £40 odd for a shop one if any of you clever types have made up one of those with the later 3 pin fly lead connector. The parts can only be a few quid and I can do some soldering! Just need to know which colours connect to which pin, the early wiring diag is not much help. Need it for the weekend as got some misfiring so thought I might try and solve it myself.

Also any idea the spark plug size on the AJP 4.2, need to get a smaller plug spanner.

[optimax sniffer]

I believe a standard serial cable will be up to the job

[Demondad]

optimax sniffer said:

I believe a standard serial cable will be up to the job

Unfortunately the later ecu has a 3 pin fly lead coming out the box so there is only the option to pay £40 for it. Unless anyone knows how to make one??

[pjenni12]

Search 'pc connection to new type ecu', (can't paste link on mobile!) there is some info there regarding pin outs etc.

Phil

[Tanguero]

I changed the connector on mine from 3 pin to DB9 so I could wire it permanently into my in car computer. I can't remember the pin assignments off hand, but I think I found them on the wiring diagram in the workshop manual. It is simply TX, RX and ground to the standard pins on the DB9

When I can get to the diagram I will have a look for you

[Tanguero]

I changed the connector on mine from 3 pin to DB9 so I could wire it permanently into my in car computer. I can't remember the pin assignments off hand, but I think I found them on the wiring diagram in the workshop manual. It is simply TX, RX and ground to the standard pins on the DB9

When I can get to the diagram I will have a look for you

[Demondad]

Tanguero said:

I changed the connector on mine from 3 pin to DB9 so I could wire it permanently into my in car computer. I can't remember the pin assignments off hand, but I think I found them on the wiring diagram in the workshop manual. It is simply TX, RX and ground to the standard pins on the DB9

When I can get to the diagram I will have a look for you

Thats a good idea. I'll check the wire colours to the 3 pin tonight, not sure how to check which is RX TX GND. I've got the wiring diagram from the diagnostic software, just needs translating for mere mortals like me!

[Tanguero]

Just had a look at my wiring and assuming your colours are the same

ECU 3 pin to DB9 socket (female)

Brown wire to pin 2 = TX
Blue wire to pin 3 = RX
Yellow/Green wire to pin 5 = Ground


HTH

[Demondad]

Tanguero many thanks. I will be using my bank holiday weekend diagnosing!!!

[Demondad]

Success!! I managed to make a cable that works, many thanks to Martin at Racing Green who let me copy down the cable connections in his workshop. You need to be pretty steady with a soldering iron. Here it is in total simplicity. Click to enlarge.