S2 Xantia Activa - immobiliser probs

[DickieG]

Richard

I've checked and do have the ecu breakout box, numbered 4126-T 55, and it's blue!

Not so sure about the 'Y' harness though, what's that like? Is it in your picture?

I've got a lead about 3metres long which is double ended, yes?

I'd appreciate a picture so that i can take another look in the rats nest of cables

What facilities does the harness tester give you? You'll see from the previous post that I haven't got a clue how to go about this but i am learning slowly. I can even make sense of the circuit diagrams moreorless

OK Mike, tomorrow I'll dig out the relevant harness take a photo and post it up for you.

As Wheeler mentions the breakout box allows you to test everything whilst its still in place so earths, supply voltage, component resistance etc. Rarely used but very useful with problems such as yours.

[superloopy]

Many thanks Richard, i'll look out for it

[addo]

Curious - are you getting a spark? Have you tried a splash of fuel through the throttle body?

Also if the ignition driver module dies on earlier cars, it will not "release" the immobiliser. This is a sneaky catch I've discovered the hard way!

[wheeler]

Wheeler, I may be well out on my fuses although the info came from a Citroën service book headed 'Xantia Electrical diagrams RHD 1998 model year RPO 7483 ->', my car is a 1998 S2 RPO 8067. Correct or not?

Unfortunitely It doesent tell you what RP number the book goes up to & you might find there may be a later book for example from RPO 8060 -> so i cant be sure thats the right book you have.

Numbers on the diagram wires near the plugs (eg; 1351) are stamped repeatedly on the wires however it seems inconsistent which order they are interposed with other factory identifiers.

Addo the numbers stamped on the wires are anything but random or inconsistent. All the electrical systems are broken down into 8 main groups & sub groups. For example group 1 is power unit (as in engine) If you look at the injection system diagram from this post you will see most of the wire & component numbers start with 1xxx & the wire numbers are similar to the component number. It then breaks down into sub groups, for example all the ignition related parts & wires are 11xx. Lokk at the knock sensor (1120), the coil pack (1135) & the ignition module (1105).
Letters in fron mean different things to eg C means fused ignition live & V means fused live sidelight feed.
M in front of a wire code identifies it as an earth so if I saw wire number M1105 I could tell that it is an earth wire for an ignition ignition system componant & going by the fact that the component number for ignition module is 1105 then it would be a good educated guess that its for the ignition module & if you look at pin 4 then you'll find thats what it is.
The exterior lighting & signaling is group 2 so you will find most of the wiring & componant codes with these items will be 2xxx. Obviously there are certain things that are multifunctional & cant be put in just one group so there are generic things Like instrument panel is just 0004, fuseboxes & diagnostic socket.
Give me a challange, give me a random wire number from a semi modern citroen Xantia onwards (not AX, ZX or XM as they used different diagrams) & i'll try & tell you what it's for or what it does.
There is something about this diagram that is baffling me though which i think must be a mistake, I've been studying the injection diagram to try & give superloopy some pointers I cant work out how the oxygen sensor heater element (1350) & the charcoal canister electrovalve (1215) get their power from fuse 11 or more specifically where fuse 11 gets it's supply from ?? I reckon it sould also be connected to the 1st output side of the double relay ?

[DickieG]

Here's a photo of the harness tester to breakout box lead, more of an elongated 'X' rather than a 'Y' really

[superloopy]

Richard, thanks. I'm sure that one of them looks like that but I tried to connect the breakout box and couldn't work out how it fits. I'll check tonite and let you know.

wheeler, I've got a lot of questions about the circuit diagrams but just how do you identify which fuse powers what and just what are IC01 and 02?

Looks like I do have a breakout box and harness, should help once I get my head around it all ..

[RichardW]

just how do you identify which fuse powers what and just what are IC01 and 02?

Just follow the wires on the diagram to see where the wire goes from the fuse back (all fuses being fed +12V). I can see wheeler's confusion - it appears that the O2 sensor and carbon cannister are connected in a big loop

IC01 and IC02 are harness connectors - one at the front inner wing, the other at the bulkhead. I imagaine that you break the harnesses here, and then plug in the breakout lead, then connect the breakout lead to the lexia. What you are trying to do is effectively place the Lexia in the harness so that it can 'see' what is going up and down the harness.

......Actually, looking at that breakout lead, it appears to be a replacement for the in car harness section, you will another lead (a Y shaped one with a female round plug on end, male on the other, and the lexia connection in the middle) in order to connect the lexia.

[wheeler]

IC = Inter Connector & the number is just to identify which one it is.

Richard, the breakout boxes dont connect to the (IC) interconnectors, they connect directly to components like ECU's & bigger relays.
The big long lead is really just an extension cable to connect either the manual or electronic breakout box to the relevant ECU harness adaptor you are testing, the adaptor harness can connect directly to the breakout box although you would have to get the Lexia very close to the car
One thing to be carefull of when using the breakout box, one of the round connectors has a green tab & the other a white tab to identify which is which but the leads can be fitted the wrong way around which could give you some strange readings.

[RichardW]

Ah... OK, I'll shut up again then

[CitroJim]

Mike,

Just before going too deeply into this, check that you have a good supply of volts at the ignition switch.

Pop off the lower steering wheel cowl and dash trim to expose the ignition switch connectors.

With the ignition on, check you have a good supply of volts on both pins of the grey connector.

I say this as I found the notorious engine loom that ruins under the rad on a MK1 Xantia had a break in it, depriving certain circuits of volts. It didn't stop it running but on a MK2, all ignition and immobiliser supplies run through this grey connector.

Also cherck that with ignition on volts are present on F25, F15, F12 and F2 in the dash fuse box.

It may be irrelevant but it will prove that supplies are reaching at least as far as the switch.

[superloopy]

Mike,

Just before going too deeply into this, check that you have a good supply of volts at the ignition switch.

Pop off the lower steering wheel cowl and dash trim to expose the ignition switch connectors.

With the ignition on, check you have a good supply of volts on both pins of the grey connector.

I say this as I found the notorious engine loom that ruins under the rad on a MK1 Xantia had a break in it, depriving certain circuits of volts. It didn't stop it running but on a MK2, all ignition and immobiliser supplies run through this grey connector.

Also cherck that with ignition on volts are present on F25, F15, F12 and F2 in the dash fuse box.

It may be irrelevant but it will prove that supplies are reaching at least as far as the switch.

Jim, that 'sounds' easy but can you elaborate in layman's terms the use of the multimeter which i'm assuming i'd use because you mention volts

Keep it simples

I'm getting quite interested in all of these new found skills (and hardware) i'm acquiring as a result of this, all gryst to the mill as they say although i never did understand just who 'they' were

[CitroJim]

Mike,

You can use a test lamp too but a multimeter is easier...

They're easy to use for this. Switch it to the 20V DC range, attach the negative (black) prod to a known good earth. When in the vicinity of the cabin fuse box and ignition switch I find one of the door check strap bolt heads is a good earth point.

Then with the positive (red) probe, read the voltage at the points stated. 12V is nominal and won't be exactly that. measure across the battery terminals to get an idea of the batter voltage and when you read at the points stated it should be close to that.

If you see a very low voltage, in the region of say anything from zero to perhaps 7 or 8 volts then this shows there is a problem. As a guide, on the car at the weekend I was seeing just 2.5V at the ignition switch.

[addo]

Wheeler, what I was getting nat, is there seem to be on many of the wires, more than one set of codes.

Yes, one set follows the identifiers/protocol you describe but - without rigorous examination - there appears to be a second set of numbers that don't cross to the same notional set of subassemblies.

[superloopy]

Mike,

You can use a test lamp too but a multimeter is easier...

Also cherck that with ignition on volts are present on F25, F15, F12 and F2 in the dash fuse box

Understood Jim, where's the location of the grey connector exactly? Will it be obvious once the cowl is removed?

And ... the fusebox end, do i do similar but locate the red probe at the top each circuit mentioned?

[CitroJim]

The grey connector is one of a trinity you'll see on the end of the thick wires going to the ignition switch. One is brown (MR), the other is black (NR) and the one you're interested in is the grey (GR) one. they're virtually flat two-way connectors with big spades on them.

Sorry for the delay in responding Mike, been in London since the early hours and not long back...