urgent advice needed

[RPWC]

My 04 Dispatch 1.9 won't fire up, no glow plug warning lights,no engine management light with ignition on.
AA been ,tested all fuses,diagnostic will not communicate with E C U, there is no power to E C U, ,and the machine cannot interrogate the EC U. He thinks it could be E C U relay,or glow plug relay or both.
When removing the airflow meter plug and probing it, there is 0.2 v on one port and 6 on another,AA man said it should be 12.
Can anyone help??

[xantia_v6]

When voltages are low, but non-zero, it is often a sign that the problem is corrosion, either at a connector or relay socket, or within one of the wires itself.

You really need to get the relevant section of the wiring diagram and trace through where the voltage disappears.

[RPWC]

There in lies the problem there isn't one available cant get workshop manual for Dispatch mk 1.
Cant be corrosion,as the van starts first time every time up till now. Been using it today

[RPWC]

This has just been a sudden thing, it was working fine earlier today, I had been fitting a new radio,went to start it and it wouldn't, as per o p, when ignition is turned on, the yellow light for glow plug relay does not come on, or the engine management light.I renewed the g p r a couple of years back,as the old one had a burnt out connector on it.
The van has always been a good starter, so I was surprised when it suddenly wouldn't today.

[Mandrake]

tested all fuses,diagnostic will not communicate with E C U, there is no power to E C U, ,and the machine cannot interrogate the EC U.

How are you determining there is no power to the ECU ? Are you measuring the power pins on the ECU connector ? If so, you're just going to have to trace the wiring back towards the battery to find the problem if fuses have already been checked, which will probably require a wiring diagram as it can be next to impossible sometimes to follow a wire all the way through various trunking, connectors and splices without one.

The ECU will have a permanent live for non-volatile memory, an ignition switched feed, and may have relay switched feeds as well. I had a problem on my Xantia recently where the permanent live to the ECU was missing due to a wiring loom fault and even though the ignition switched feed was still present I could not start the car, nor could I enter the immobiliser code or communicate with a Lexia.

It took me several days (partly due to rain) to track down the location of the break in the wire - which was in a completely inaccessible location in a wire bundle under the radiator - so I had to run a bypass wire to fix the problem without dismantling the entire front of the car...

He thinks it could be E C U relay,or glow plug relay or both.

Some how I doubt a glow plug relay would prevent communication with the ECU. And while it might make the engine a bit harder to start, on a modern diesel the glow plugs aren't always needed for starting unless you're well below zero.

When removing the airflow meter plug and probing it, there is 0.2 v on one port and 6 on another,AA man said it should be 12.

12 volts being correct seems quite unlikely - modern cars have almost universally adopted 5 volts for the "sensor reference voltage" since at least the 1990's... before that there were a few that used 9 volts but I don't think any ever used 12 volts - the reason why is you want a regulated voltage that doesn't vary with battery voltage. This is easy to do with 5 volts but not practical with simple circuitry at 12 volts.

No offence to your AA guy but from some of the suggestions he's made it sounds like he's clutching for straws and the electrical side is not his strong point.

[RPWC]

Electrics is not mine either, I am going to get e second hand ECU relay from a breaker today, to test it,but I am thinking it will need to go to a Citroen specialist. There is a main dealer not far away, but I don't rate them very much, there is also a 'back street ' French car specialist, who may be able to help. I don't think its worth trying my local garage, as if the AA diagnostic machine couldn't communicate with the ECU, then its a Citroen only machine that will.
I had this problem with my mother's Peugeot 107,earlier this year, only a Peugeot diagnostic machine would talk to it.

[GiveMeABreak]

This has just been a sudden thing, it was working fine earlier today, I had been fitting a new radio,went to start it and it wouldn't.
The van has always been a good starter, so I was surprised when it suddenly wouldn't today.

Rich, I've just picked up a small but maybe significant point from your post that I missed the first few reads. Am I right in saying it worked up until you fitted a new radio? Have you wired anything to the ignition wiring, or any other wiring for that matter? The nature of the multiplexed wiring in modern vehicles means you can't just connect any kit up without risking issues with the car's network communication. As the problem seems to have happened shortly (?) after fitting the radio, as a matter of elimination, I would first consider putting everything back as it was and seeing if that has been the cause.

Also if you provide your VIN I'll have a look at the wiring.

[RPWC]

Marc, the radio is just a standard iso connector, the only alteration I made was with ignition live and permanent live, as the radio turned on every time the ignition came on, so swapped them ,and somehow blew radio fuse, how I don't know, as there was no live to earth contact, the cables are plastic sleeved to avoid this. Also I have removed the radio completely,and no difference.
Will send vin by pm.

[wheeler]

Just a few points to quickly add to all the points above. Assuming this is a DW8 then this does rely on glow plugs to start, if less than 3 glow plugs are operating this engine will struggle to start.
The AA guy is right, the air flow meter plug should have a 12v and a 5v feed with the ignition on. If these are not there combined with no diag comunication this suggests missing feeds/earths to ecu or ecu is dead. However the mk 2 dispatch is notorious for the wiring harness getting damaged where it runs above the steering pump under the black conduit. The conduit 'eats' into the wiring.
The mk 2 dispatch is also not multiplexed

[RPWC]

Its a mk1 2004 1.9. will check what you say anyway, is there a "secret "fuse somewhere that powers the ecu? all fuses ,earths and lives have been checked,

[RPWC]

Just a few points to quickly add to all the points above. Assuming this is a DW8 then this does rely on glow plugs to start, if less than 3 glow plugs are operating this engine will struggle to start.
The AA guy is right, the air flow meter plug should have a 12v and a 5v feed with the ignition on. If these are not there combined with no diag comunication this suggests missing feeds/earths to ecu or ecu is dead. However the mk 2 dispatch is notorious for the wiring harness getting damaged where it runs above the steering pump under the black conduit. The conduit 'eats' into the wiring.
The mk 2 dispatch is also not multiplexed

I had a look at what you describe, mine has a cable tidy type cover on it, with a split in one side. I managed to get a meter on to pone of the wires, a thick white one, and that is reading 12v, will try the rest when I finish work later on. All glow plugs renewed last year.

[wheeler]

You need to take the P clips off, take the conduit right off & strip back the insulation tape where it runs over the top of the steering pump along the engine, seperate out all the wires & visually inspect each one carefully, the ribs in the conduit cut through the insulation & eventually the copper strands. I have done this repair plenty of times, you normally find 3-4 wires needing repaired & down to the last strands of copper. Theres no point in probing with a meter, you need to visually inspect.
If you have confirmed all your lives & earths are present (there are normally several of each) at the ECU then it sounds like you have a dead ECU then which would be quite unusual. Did you get hold of a correct injection wiring diagram?? Also are you checking the supplies direct at the ECU plugs ? If so you need to be very cautious if doing this without a breakout box. If you start probing pins etc into the terminals in the plugs as they are very fine they can end up fitting like a cock in a sock & actually causing poor connections.

[RPWC]

You need to take the P clips off, take the conduit right off & strip back the insulation tape where it runs over the top of the steering pump along the engine, seperate out all the wires & visually inspect each one carefully, the ribs in the conduit cut through the insulation & eventually the copper strands. I have done this repair plenty of times, you normally find 3-4 wires needing repaired & down to the last strands of copper. Theres no point in probing with a meter, you need to visually inspect.
If you have confirmed all your lives & earths are present (there are normally several of each) at the ECU then it sounds like you have a dead ECU then which would be quite unusual. Did you get hold of a correct injection wiring diagram?? Also are you checking the supplies direct at the ECU plugs ? If so you need to be very cautious if doing this without a breakout box. If you start probing pins etc into the terminals in the plugs as they are very fine they can end up fitting like a cock in a sock & actually causing poor connections.

The nut holding the p clip is rounded, so I may end up having to grind it off, no I haven't done any probing at the eco, the AA man had a small test meter and was checking for power at the plug. I still fail to see how it can just suddenly give up like this? there's nothing I could have done to cause it,it was just a simple radio swap, the old unit was not o e anyway,it was one I fitted a few years back, and I just bought a better on,which was working fine,the only reason I removed it was to swap the battery live and ignition live, for reason described in a previous post.
I'm going to double check all the fuses again,what rating would the ecu fuse be?

[Mandrake]

Old wiring doesn't need an excuse to fail, it just happens sometimes, either through chafing or corrosion.

Mine failed for no apparent reason at all - one day it was working the next day it failed when the central locking was unlocked.

The wire must have been hanging on by a thread and finally gave up.

[RPWC]

Having checked the harness around the p clip, I found some slight chafing of the outer sheath on a thick white wire, but it hadn't split at all,all the other cables were checked individually,and none showed signs of damage.
I have re checked all the fuses,one by one,all intact,so its off to the garage tomorrow.
What I cant decide is where to get it taken to.
I have three choices, my local garage is just across the road,and the owner is a friend/customer who I know well,he has helped me out of a hole in the past a few times ,so I feelI should offer him the job first,but if the AA Bosch diagnostic machine couldn't get into the ECU, then what chance has his got? Second choice is a back street French car specialist,about 7 miles away,I got a second hand hydraulic pipe for a BX from him years ago,or do I contact the main Citroen dealer,who I know will likely rip my eyeballs out.??