wanted-black block connector 15 pin for hydractive ECU

[White Exec]

John,

That's a useful finding that Graeme has made, a few of posts above . . . that on a vehicle equipped with a speed interface, the speed sensor IS capable of driving the suspension ECU direct (to include the otherwise-unused pin 6, and without the interface in circuit).

This offers a good diagnostic path for investigating a fault in the speed sensing circuitry, when it's unclear whether the sensor or the interface has failed.

From this too, it would appear that the speed interface is there not principally for the benefit of the ECU, but for the other things it feeds - eg RH display/trip computer. Still unclear, of course, just what kind of signal processing the interface actually does. A job for sensor, bench and 'scope

Chris

[Aerodynamica]

Yep and I'll run it for a week or so then rewire the speed interface too and reconnect the speed sensor to the interface and hopefully that'll allow both to work

Just need that 15 pin connector....

[xmexclusive]

As far as I can see looking at the circuit diagrams pin 6 is only used on non engine ECU cars.
Where it is used the wire from the pin 6 is earthed before reaching the speed sender (154).

I think the earth for the wiring to the speed interface (56) is defective or missing.
This is leading to a very poor signal.
Adding the wire through pin 6 completes the circuit as it would be in a non ECU car.
It might be worth trying that wire to earth instead of pin 6.
Would a dodgy speed signal cause unstable running?

John

[Aerodynamica]

Don't think so John the 2 litre turbo doesn't use the speed sensor for the engine but the v6 does according to the factory manuals

[xmexclusive]

The wiring I describe is taken from the original factory instructions for the XM.
Not the dealers maintenance pages.
Copies of these should have already been sent to you by Chris.
Pin 6 of the speed interface (56) should be 12v and Pin 9 earth.

Single wire speed info feed is correct for many Mk1 XM's.
It becomes the standard for all Hydractive II ECU's.

Check the interface feeds and try earthing that wire before you go plug rebuilding.

John

[Aerodynamica]

I've checked the earth at pin 9 and the supply at 6 and they check out but the single feed from the pin 1 to the ECU is still duff suo there's a second break in the continuity which seems unbelievable. If that is the cause of the original problem now that the speed sensor is proven ok it doesn't explain why the speed information on the trip computer is wrong. I do suspect the 9 pin plug at the interface add the female pins visibly look bent. Still get no buzz out using a pin though.

According to the diagrams I have the wiring looms changed in about 1992 to eliminate a whole set of block connectors affecting the speed sensor wiring. It previously went through the bulkhead, through a red multi plug to the dashboard, to the interface then via grey 5 pin plug to the engine room then to the ECU. From that date out was wirerd point to point from sensor to interface and interface to ECU. If there's no interface it wired directly from Dowd sensor to ECU connector with no connections in between. It seems this is identified by the wiring loom from the speed sensor traveling along the back of the engine bay Unger the scuttle along to join the wiring loom at the driver side sphere. Your to this it vanishes through the bulkhead into the dash area. Mine seems to agree with the later type. Everything checks out from what I can see

Anyway the connections at the speed interface are next to be looked at

I've also managed to disassemble the rubber filled multi plug. If I can see how the individual pins are clicked into their respective bores I might be able to release them. I am thinking of replacing all of them and refilling the plug with molten rubber again... Might be crazy, might just work!

[White Exec]

Hi Graeme,

As you've actually found a break in the wiring (from output of interface to input of ECU) it does make sense to fix this.
Personally, I wouldn't try to strip and rebuild one of the plugs. It will never be as good as 'new', and getting hold of another one I think is the far better option.

The bent 9-pin connector doesn't sound good.

[Aerodynamica]

There's at least two breaks! Yea I think the plug is toast because I doubt I can remove any of the pins without wrecking them

Hydractive is still working properly but I want to do the final rewiring properly- it's in a temporary state now

As for the 9 pin plug, I wonder if there has been investigation on this part before - certainly the black box spotted interface was loose in its mounting when I first looked at it. Anyway I still have no access to the workshop for two more weeks (it's very frustrating as it's been six weeks) and I need access to soldering iron, ramps, lights! Etc. Anyway thanks for all the help folks

[xmexclusive]

All the XM plugs and the separate pins were available from Citroen for repair and making up new wiring.
There was also a box of release tools for the pins.
I regularly repair and make up cabling.

Graeme, I too looked at one of the multi plugs today and started peeling bacl the black rubber.
On a recovered white ECU plug as I have plenty of these.
I should have a length of wire with pin to send you as an option.

John

[Aerodynamica]

Hi John, do you mean these replacement plugs can be got from Citroen? I'll admit I tend not to even consider contacting the dealers - I just assume the dealers will be useless..

If there's a replacement 15 pin plug available I'd be very interested.

Haha, sorry about the odd words in the previous posts - I'm using my phone during the day and it seems to be keen on changing some words that I don't always see!