Because it is not easy to get at all the relevant wires and connections when the ECU is plugged in for normal operation.
So what to do about that ? You need a transition board.
In our factory we make electronic products which have a similar problem.
So we make transition boards.
That is a printed circuit board with the “male plug” at one end and the corresponding “female socket” at the other end. In between tracks connect male to female and we insert test pins, which are little wire hoops, to hang an oscilloscope probe on. That way all the signals and voltages can be checked in normal operation easily and quickly.
That wold help Sloth fix his problem.
In the case of the XJ-S I would also put small terminal blocks on the PCB for various connections. This way you can run a wire from the board up to the engine bay which really helps trouble shoot some types of faults with the engine running.
Easy to do ? Well, maybe. We order batches of PCBs from China every month, cost very little.
The sticking point is the ECU plug and socket. I have an aftermarket EFI system in the coupe and took out the ECU and plug a long time back, still working. I think I gave it away to somebody.
More than likely they are unobtainium, but there may be a work around.
Anybody got a dead ECU + plug they can send me to look at ?
Honestly with the little oscilloscope L connectors you can just about do that job on the existing terminal connectors inside the box by just leaving the side of the case off:
That said I think the MoBo parts are either AMP 825213-x OR AMP 827137-x
The exterior harness side connector is still available from various sources - fleabay / alibaba- as it was used on Porsch, BMW and some other ECUs I believe.
Thanks for info Paul.
Yes, the plugs are available from an Ebay source in UK.
The socket in the ECU does not seem to be stocked anywhere by the usual suspects, but you can order them from the factory with an MOQ of 176 pcs.
I used the part number you gave and it looks about right.
Octoparts gave an outfit called LTL claiming 1922 pcs in stock, but they look like a commission agent and as such may not be reliable.
I can see it is no problem getting a probe on the outer pins of the socket, the inner pins would be more of a challenge. Of course you can lift the PCB and solder wires to those pins for troubleshooting.
Up to now never had any problems with the ECUs in any Jaguar I owned. If I did it can be a lot easier to troubleshoot with a transition board.
If I ever get my hands on the right parts i will make myself one.
Using the two screw holes seen in the picture, it might be possible to create a bolt-on probe board/device that uses POGO probes to create that breakout board.
those look very similar to standard (at the time) serial port connectors on PC : 9 and 25 pins were used , names DB9 and DB25, mostly gone in todays laptops
I thought you were looking for the “engine” side connectors, which are probably more specific multipoints to get to the engine loom
i use mostly GM connectors and sensors!
bought 1994, upgraded 1999, upgraded again 2006,new PC board ,works very well altho time programming maps!
best part is i can use easy to get sensors , and connectors,cheap!
does what i need!
BUT the original designer/builder has retired,sold company , new people dont do V12 anymore!
if i ever decide to change , probably go Megasquirt!
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