Solved: C5 immobilizer forgot the key?

[antonzlo]

Not eco mode yet
I did try your theory, but it doesn't differ whether chip is in proximity or not - same "key reminder" warning both times

[ozvtr]

My friend with launch has read the car, there were no relevant faults apart "engine ecu communication continuous fault" in airbag module

That doesn't make a lot of sense. What's with 'in air bag module' stuck on the end of the sentence? Sorry, but that's a bit confusing.

If I am reading this sentence correctly and Launch reads a communication fault with the engine ECU then of course the engine wont start.
The 'ESP malfunction' may be relevant as some cars' engine ECU communications go through the ABS/ESP ECU.

I would check the power supplies (fuses) to the engine ECU first. That's IF Launch is correct. But that's all We've got to go on ATM.
Possibly inspect the ABS/ESP module's electrical connector for corrosion. Inspect the engine ECU's electrical connector for corrosion.

Typically, the engine ECU "asks" the BSM (over the CAN BUS) to run the fuel pump for a second when the engine ECU is first turned on. This primes the fuel system. But if the engine does not start or run, the engine ECU will not 'tell' the BSM to run the fuel pump...and the fuel pump won't run. This is a basic overview for a PETROL engine. Diesel and direct injection is different. If the engine ECU does not get the unlock code it will neither run the coils nor the injectors. Fuel rail will retain the primed pressure.

In the older VAN-BUS cars, the starter was directly connected to the ignition switch (mostly, autos were a bit different). On later CAN-BUS cars the starter is connected to the BSM and a "request" is made over the CAN-BUS to run the starter. This means that ECU's had the "power of veto" and could make a request for the starter NOT to run (for one reason or another, like the engine ECU not receiving the unlock code).

Most ignition locks have a switch to tell if the key is still in the ignition.

From what I have to go on here, I don't think the problem is with the transponder chip in the key.

[wheeler]

From what I read in the other topics ECU cuts out spark, not fuel
+ when trying without key's pcb it was cranking still.

Not correct, the ECU would never let fuel be pumped into the engine without a spark as this could flood the engine & catalyst with fuel & can cause damage.
Some immo systems will cut the spark and fuel. I honestly can remember if the spark is inhibited on these. The ECU is locked & it will prevent the injectors from firing, From memory i believe the in tank fuel pump does still operate when the immo is active but makes no difference as the injectors wont operate anyway.

Im also a bit confused, Is the starter motor operating or not? as Oz says the immo on a mk1 C5 does not inhibit the starter operation so if the starter is not turning its not immo related.

As for the key in the ignition beep test, on PSA cars yes this is triggered by a transponder chip rather than a switch inside the ignition barrel however be aware that any transponder chip (of the same type) will trigger this warning even if its not programmed to the car so this is not a good indicator that the key is being recognised.
I would probably say forget the immo for the time being & concentrate on basics, the fault finding process will differ depending on if the engine is cranking or not so can you please confirm is the engine turning over normally & is the battery in good condition?

[darbuck]

Agreed the starter should crank if there is good battery immobilizer doesn't affect it. Fueling and possibly spark is inhibited. You may need to reprogram the key it may have been damaged magnetically or something.

[ozvtr]

From memory i believe the in tank fuel pump does still operate when the immo is active but makes no difference as the injectors wont operate anyway.

The BSM must receive the "engine running" code from the CAN BUS or it will shut down the fuel pump. This is also a safety feature in case the car has an accident.
If the engine can not run for one reason or another the fuel pump is cut.
I just tried this on my VAN BUS C3 and the fuel pump will not prime with the immo active. I would say it would be the same on most cars.
The primed pressure and fuel in the injector rail are enough to get the engine started then the fuel pump kicks in when the engine ECU says the engine is running.

[ozvtr]

I am still concerned by the "engine ecu communication continuous fault".
This is typically a fault with the engine ECU failing to talk to the BSI.
Why?

[antonzlo]

Wheeler, starter is turning. And, once again, we managed to start the engine for 2-3 seconds and it ran well. This proves mechanical part is okay.
About key reminder - how far can it read the key?
Ozvrt, we have checked ECU connector, it's perfect. It may be ECU fault or some problems, but I suspect if there is no valid key BSI might cut communication to prevent key flashing, for example.

[Hell Razor5543]

I wonder if the coil around the ignition barrel might be at fault?

[Paul-R]

This sounds like the problem I had years ago on our Xsara 2.0Hdi Estate. By measuring the voltage at the fuel pump I discovered that it was only being fed power when initially starting up. The power stopped after a few seconds so that the engine would then die.

I checked the power at the fuse in the fusebox and the power was only being supplied for a few seconds there so something was amiss between the fusebox and the engine ECU or BSI. I wasn't able to find out exactly what the problem was so bypassed said problem by feeding the fuse from a different ignition controlled source.

So, try running a temporary live feed to the fuel pump and see whether the engine will run as long as is required.

[antonzlo]

Thanks for the advice - is it underneath the car?
And I was wondering about self-tests in OBD2 diagnostics - how are they made and when? Because if fuel pump is not working shouldn't the fuel test fail?

[Paul-R]

On all our PSA cars access to the top of the fuel pump is on the RH side under the rear seat cushion (base) behind a large plastic grommet.

[antonzlo]

As for the key in the ignition beep test, on PSA cars yes this is triggered by a transponder chip rather than a switch inside the ignition barrel however be aware that any transponder chip (of the same type) will trigger this warning even if its not programmed to the car so this is not a good indicator that the key is being recognised.
I would probably say forget the immo for the time being & concentrate on basics, the fault finding process will differ depending on if the engine is cranking or not so can you please confirm is the engine turning over normally & is the battery in good condition?

You are probably right. The key reminder warning shows even if the key is just near the lock, not inserted. The coil was around 20 Ohms, so it works. I'll check fuel pump voltage and will reply.
Checked the fuses inside and in the bonnet - all are intact. Without ECU fuse it just cranks, and with - tries to start but fails.

[antonzlo]

This sounds like the problem I had years ago on our Xsara 2.0Hdi Estate. By measuring the voltage at the fuel pump I discovered that it was only being fed power when initially starting up. The power stopped after a few seconds so that the engine would then die.

It's 12v sometimes when turning on ignition and always 2-3 sec when starter runs. If I try to start a few times, but fast ( engine doesn't spin much) it will start for a sec, but then dies. The pump is humming, but the sound changes after a second (pitch drops). Also sounds like some valve is closing there but I don't think there are any.

[wheeler]

From memory i believe the in tank fuel pump does still operate when the immo is active but makes no difference as the injectors wont operate anyway.

The BSM must receive the "engine running" code from the CAN BUS or it will shut down the fuel pump. This is also a safety feature in case the car has an accident.
If the engine can not run for one reason or another the fuel pump is cut.
I just tried this on my VAN BUS C3 and the fuel pump will not prime with the immo active. I would say it would be the same on most cars.
The primed pressure and fuel in the injector rail are enough to get the engine started then the fuel pump kicks in when the engine ECU says the engine is running.

Agreed about the fuel pump cut off if the engine is off, It should initially prime & then should only operate when the engine is turning so it can operate on cranking, if the cranking stops the FP stops. I am sure on some models during fault finding i have tested this & when the immo is active the fuel pump still runs on crank, I currently dont have any PSA cars to try it on.
As for this fault, its basics.
Fuel: does it have enough fuel in the tank, dont trust the gauge. if any doubt stick a can of fuel in.
Will it run on easy start?
Can you see the engine speed info on diagnostics live data?

[antonzlo]

It was fuel. It's absense. Do I change the fuel quantity sensor? Or is it the gauge?