Urgent: 1.9TD ECU functions

[CitroJim]

I have now got TehAgent's Xantia running very nicely with an older mechanical injection pump following his original pump springing a masive leak. It flies and runs like a clock.

I have just got to finish off the electrics. Now I have a problem. The BoL is useless for electrical diagrams and does not even hint at the ECU controlled Bosch Pump wiring. It only shows the mechanical pump wiring for the pre '98 diagrams and the wiring for the post '98 Xantia TD bears absolutely no relation whatsever to what is in Ians car

I presently have the ECU in place as it is needed to operate the glowplug controller. If it is left disconnected the glowplug controller does not work.

I'm now suspecting that if I leave the ECU out, neither the tacho nor the speedo will work. Am I correct? I'm basing this on a wiring diagram I have for a 2.1TD that shows the ECU operating the speedo, tacho and glowplug controller. The 2.1TD wiring diagram bears more resemblence to what is on Ian's car even though it's for the Lucas EPIC pump.

The olny downside to having the ECU still in circuit is that the Engine Management light is on permanantly. I can always chop the wire

I know I could do loads of rewiring and do away with the ECU but our intention is to refit the original electronic pump as soon as it is fixed and time is not on my side to undertake a major rewire.

Does anyone know if any ECU damage is likely if it is left running without the electronic pump bits connected? I suspect not as everything is effectively open circuit.

I would give anything for an authoritive wiring diagram for the electronic 1.9TD right now 8)

[weety]

dont know if this helps but i have an intermittant electrical fault on my 1.9 td xantia that disables the rev counter, brings up the engine ecu warning light and glowplug light and makes the car run er badly

doesnt effect the speedo though

my car seems to drop into a 'limp home' mode when this happens so getting rid of the ecu may not be an option

sorry i cant be more helpful

[CitroJim]

Actually Weety it has been of great help

I found a Peugeot wiring diagram here:

http://peugeot.mainspot.net/wiring806/index.shtml

And as Peugeot and Citroen use the same wire numbers etc. it is very similar to what I need.

Without the ECU the tacho will stop but the speedo will keep going, which is good.

Your problem is I think, looking at the diagram, either the loss of your TDC sensor into the ECU or the loss of the needle lift sensor. Check your connectors first-off, the TDC one particularly is not in a clean place.

I just want it to stop raining now so I can get on with the car, It is pouring down here

[weety]

Actually Weety it has been of great help

I found a Peugeot wiring diagram here:

http://peugeot.mainspot.net/wiring806/index.shtml

And as Peugeot and Citroen use the same wire numbers etc. it is very similar to what I need.

Without the ECU the tacho will stop but the speedo will keep going, which is good.

Your problem is I think, looking at the diagram, either the loss of your TDC sensor into the ECU or the loss of the needle lift sensor. Check your connectors first-off, the TDC one particularly is not in a clean place.

I just want it to stop raining now so I can get on with the car, It is pouring down here

pouring here as well.....i can guess where the tdc sensor might be but where is the needle lift sensor?

trouble is without the ecu your car will be so slow that you wont need a speedo

surely the pump would be an 'add on' to that system so if you powered the system up it would still work (doesnt it just tell the pump what to do rather than draw information from it?)

[CitroJim]

Hi Weety,

The Needle Lift Sensor is on No.3 Injector. Count two in from the cambelt end of the engine and you'll see a little black wire coming from the injector body by the leakoff pipe going to a brown connector attached to the top of the engine. This in turn has a black connector plugged ito it with a grey wire going off into the engine loom. This one too can get mucky so it's worth snapping it apart and cleaning the contacts.

Ian's car now has a fully mechanical pump so the ECU is totally redundant except for the glowplug control and tacho drive No loss of performance, it goes like a scalded cat

Basically, all the ECU does to the AS3 Pump is to (apart fom the coded keypad) adjust it's timing by reading the Coolant Temperature Sensor, the TDC Sensor (for engine speed), the Needle Lift Sensor and the throttle position, via the pot on the top of the pump and setting the timing as appropriate. The pump itself is actually just a standard mechanical pump with a solenoid controlling the timing advance ring inside. If all the electronics pack up the engine will still run (albeit a bit off, timing-wise) so long as the stop solenoid can be operated.

Because it would be so easy to hot-wire this pump, Bosch went completely mad armouring the stop solenoid Without the armour, the coded keypad would be as much use as an ashtray on a motorbike