Multimeter has ruined bsi?

[seanrx]

Wire test fail? Lordy.

Am hoping not.

My coil pack's wire harness to the bsi, I was testing it to locate a control/power pin with the multimeter.

But I think I've messed up, rushing the job.

I put a probe onto battery pos+ and other probe onto ALL of the six harness pins individually, I did get a 12 volts reading on what I now know are the cylinder control wires.

Is this the reason that I see no spark on the plugs, when I test coil pack out of engine? Plugs were earthed.

Now I have fault codes on all four cyls, not just one.

Have I fried my bsi/ecu?

[MattBLancs]

Wire test fail? Lordy.

Am hoping not.

My coil pack's wire harness to the bsi, I was testing it to locate a control/power pin with the multimeter.

But I think I've messed up, rushing the job.

I put a probe onto battery pos+ and other probe onto ALL of the six harness pins individually, I did get a 12 volts reading on what I now know are the cylinder control wires.

Is this the reason that I see no spark on the plugs, when I test coil pack out of engine? Plugs were earthed.

Now I have fault codes on all four cyls, not just one.

Have I fried my bsi/ecu?

Have you reset codes and see if they come back? I'm wondering if you have "someone has unplugged the coil pack" codes logged - IE ECU logged open circuit whilst you had coil pack unplugged (assuming that's what you did rather "back probing" the terminals whilst coil pack remaining connected?)

[seanrx]

Hi.

Codes present are 0351-4. The depollution fault.

My basic obd can clear them but car still turns over only once then off.
The bsi reset fails too.

I have'nt back probed the harness, but then I am not sure of what signal I should read.

I was on YouTube and the coil pack video was for a 4cyl three wire harness. Mechanic gets a 12v reading on one pin (control/power) and switches to ohms setting for remaining two.

My multimeter results were nothing like his!
Seems that of all the coil pack videos, all from USA and nothing listed for a PSA inline setup.

[CitroJim]

If you had the multimeter set to volts then the likelihood of damage is very low... Set to ohms and you are more likely to damage the meter itself. Only if you were switched to amps might you have but again only a low probability unless you hit something really sensitive...

You can't really test a coil conclusively with a multimeter. You can check the windings have continuity but that does not guarantee it'll be good or able to produce a spark. Modern coil faults usually manifest themselves as misfires and often only when hot.

It won't, for instance, detect shorted turns which is what often causes a failure. Continuity on a mater will show but just one shorted turn can be enough to damp the coil so much it cannot generate a spark or only a very weak one.

Also, there are often two or more coils in the same pack and it's unusual for them to all fail simultaneously.

Unless the wiring diagram shows the internal arrangement of the coil continuity and resistance checks can be very misleading and confusing...

[seanrx]

The video by Ratchets&Wrenches, made it look so easy!

But his coil pack is opposing rather than inline and not a French car, which makes it easier.

Also read that obd readers, their cylinder positions start from cambelt/driver side. Cylinder 1.

So a 0351 (cyl 1) fault reading will actually be on cyl 4/driver side of a PSA engine. More confusion.

And a 4 cyl firing order: 1-3-4-2

[CitroJim]

The video by Ratchets&Wrenches, made it look so easy!

Sadly, they often do!

Wat exactly is the problem you are having that leads you to suspect the coil and BSI? I may have missed the pertinent bit knowing me, I'm good at that

Yes, the French convention to label cylinders the opposite does confuse... Confused me a few weeks back when working on a classic Mini for the opposite reason - that poor car now has its plugs leads numbered incorrectly

[seanrx]

The problem?

After fitting a new alternator and driving for 20 miles, the car went into slow limp home mode. 'Depollution Fault' flashed up and I read an 0352 fault code. Just one cylinder fault.

My attempts with the multimeter was to find where in the system the fault was.
At the coil pack side or ecu side?

My shoving 12 volts down the coil control wires to ecu has faulted the other three cylinders.

So now I can't perform the 'coil pack out and ground the spark plug' test.
But I did remove the sparkplugs to Ohms test, all okay.

[wheeler]

Firstly the BSI is not connected to the ignition coil.
I reckon the only way you could have done damage like this is if the meter wires were left in the amps measuring configuration, in this cas it would be just like putting a piece of wire directly from the battery to the component.
I also agree that a windings resistance check is not really a good way to test a coil, i have replaced plenty of faulty coils that show ok on a resistance check.

[seanrx]

No damage, that's good news.

Meter was on DC and actually gave a reverse reading, black probe to battery pos+.

But if I had not faulted the other cylinders, would a spark plug test have worked? As described in my previous post.

I have located two possible Lexia diagnostic centres, so come next week should have a result of some kind.

[Hell Razor5543]

There are some Forum members who have Lexia equipment and are also willing to help out other members. Although the Forum Moderators do try to keep the list as up-to-date as possible, some of the people on the list may no longer respond;

https://www.frenchcarforum.co.uk/forum/ ... hp?t=56452

[wheeler]

Can you see engine rpm in live data? Are you getting an injector switching signal? (A noid light is your best friend here).
The most likely cause of complete loss of spark is a crank sensor fault. This would also cause no injector switching signal.

[seanrx]

Live data? Lexia? Not yet, mid week sometime.

Was faffing with car again today. My four cylinder faults are now back to one. Overnight must have improved things.

Also, I need to confirm the spark plug test as in my earlier posts.

All four plugs do not spark when ground, am using multi ground plugs. The jump cable is not damaged.

These type of plugs will/should show a spark just like a single ground?

Apart from that test, nothing else I can do on a cold miserable driveway!

[wheeler]

All the spark plugs must be grounded at the same time for the spark to work correctly.

[seanrx]

At same time? So that's four jump leads to be used.

My battery (or any battery) neg post won't have the space!
Many thanks for the confirmation.

Also I have located a local ex Citroen master tech with, he says, a diagnostics even more advanced than Lexia.

So we'll see how bad or just okay my 19yr old C5 is running.

[wheeler]

My battery (or any battery) neg post won't have the space!
Many thanks for the confirmation.

Remember you can also earth on the engine block, gearbox etc.