Is injection relay module failure common with Xantia S1s?

[octinum]

Next problem. I searched for diagrams to do my homework, but Haynes didn't have the injection related things.

TL, DR; A fuse in the engine bay blows when I turn on the ignition with the double-relay near the ECU is connected. It doesn't blow when I turn on the ignition with that double-relay unit disconnected. I am looking for common faults downstream of that double-relay, including the double-relay box itself.

My car is a 1997 Series 1 2.0i 8v VSX. It has the 8-valve XU10J2 engine, and ORGA no seems to be 7400 if I'm looking at the correct place. The car was an auto (with the ZF 4HP14 box) but converted to manual a few months ago.

This problem started last week. The engine died while I was on the road, and both the red and green lights on the immobilizer keypad started to light up when I turned on the ignition. Checking fuses, I found that the fuse which I think is F7 in the engine bay was blown. It was a 10A fuse, but of course it may have been replaced before me as no fuse box diagrams I found showed a 10A fuse at that slot.

I replaced it with the 10A high beam fuse of one side temporarily, which gave back ignition. I left the car in the shop for brake and fluid (oil&coolant) maintenance on Thursday. I know they ran the car since Friday because they brought the engine to operating temperature multiple times.

I picked up the car today, and sure enough, the engine died at the 3rd kilometer. I pulled over, with the same symptoms. I replaced the same fuse with another 10A, which blew in seconds. Then I disconnected the battery, replaced the fuse with the 20A ABS control unit fuse. That one also blew. Finally, I disconnected the double-relay unit that was in the housing that holds the ECU and Hydractive control unit, replacing the fuse with another 20A from the interior fuse box, which did not blow.

I then reconnected the double relay thing, and that last 20A fuse also blew when I turned on the ignition.

Any ideas? A wiring diagram for the XU10J2 could also help. The fuse I'm referring to is third from bottom left in the photo (empty in the photo); above the beige 5A one and below the 10A red one.

[mickthemaverick]

Another member, Old Guy, has begun to post many Xantia PDF's on his new thread at viewtopic.php?p=877953#p877953. He may have the info you need in his archive so maybe PM him and see if he can help. Good luck.

[xantia_v6]

For the 1997 model year, F7 is the main injection/ignition fuse and should be 25A.

[octinum]

Thanks @mickthemaverick and @xantia_v6, both posts are gold!

I had to leave the car on the road yesterday. I'll take new fuses I have at home and try inserting 25A. However, I'm also trying to find out what could be causing this. The car was driving fine (in terms of that specific fuse) for the last 40k kilometers, and this started last week. Something must have changed.

I also noticed that yesterday's issue happened right after I pushed the engine to high rpms after it was warm to accelerate to change lanes(*). I'm not sure if it is related at all, but again, wasn't happening before last week.

(*) In Turkey, some people are somehow convinced that when you see a car signaling to the lane you are in, you accelerate to prevent that from happening. You need to be prepared.

[xantia_v6]

I looked for the engine ECU diagrams for your car, but I don't seem to have them. I believe that your car is non-catalyst, which would be an R6A engine code, but they were not sold in the UK, and my diagrams are all for UK cars. I do not even have the correct diagram for the catalysed version (code RFX), as the Citroen wiring diagram book does not include it for 1997 (I think that for 1997 all 2.0 were 16V in the UK).

Here are the 1996 injection diagrams for your engine type, but note that the fuse allocation was different in that year, F7 was changed to F10 for 1997.

[octinum]

This worked great @xantia_v6! If you visit Turkey, you, along with other friends here, need to visit Ankara to sign a dedication plate I'll put on the car. "On the road thanks to...".

Now, in case this helps someone else (I'll take photos as well), I didn't have the time to figure out how exactly the system works from the diagram, but I started following whatever comes out of the double relay. Due to the intermittent nature of the issue, static continuity tests with a multimeter didn't work reliably. I tried to check the wiring to the individual components.

The double-relay has connections to, among other things; speed sensor, injectors, canister electrovalve, ECU, ignition coil block. I started with the familiar ones, and found the significantly degraded wiring at the ignition coil wiring, close to the ignition coil block. I'm talking 10cms of failed wire insulation. They were around the hoses to the heater core. The plausible explanation is, they were not touching by some God's will (whichever you pray to), and when I started driving the car, vibration and heat cycling started to further the damage, causing blown fuse at random times.

When I separated them visually and tried a fuse, it did not blow. It even didn't heat up at the blades (though, of course, I only ran for seconds). I'll be driving back to the garage in a bit, with connector kits I can find at home (I'm still organizing my inventory, so hopefully I'll find something). I intend to just cut the damaged wiring, extend with known good wiring, and add corrugated protection around them.

Will report when done, sir!

I looked for the engine ECU diagrams for your car, but I don't seem to have them. I believe that your car is non-catalyst, which would be an R6A engine code, but they were not sold in the UK, and my diagrams are all for UK cars. I do not even have the correct diagram for the catalysed version (code RFX), as the Citroen wiring diagram book does not include it for 1997 (I think that for 1997 all 2.0 were 16V in the UK).

Here are the 1996 injection diagrams for your engine type, but note that the fuse allocation was different in that year, F7 was changed to F10 for 1997.

<images were here>

[mickthemaverick]

Well done that man, I'll look forward to seeing the pictures!!