Problem with my ECU. My car doesn't start.

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King222
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Problem with my ECU. My car doesn't start.

Post by King222 »

My car is a Peugeot 306, 1.6, gasoline, year 2000.
My car doesn't start and after checking everyting else we came to a conclussion it's something related with my ECU.

I remember I had problems with my battery a few months ago so apparently that could damage the ECU.
I already located my ECU, the problem is that I can't change that to a new one or a used one just like that, right?? it's more complicated than that because the key it's encoded and has to match the ECU or something like that.

So what are my options?
Can I repair the old ECU? Can I do it myself? Can I change it for an unlocked ECU?? Is there any other way to start my car??

Thanks in advance.
Last edited by King222 on 25 Jan 2021, 16:08, edited 1 time in total.

wheeler
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Re: Problem with my ECU. My car doesn't start.

Post by wheeler »

It depends whether it’s multiplexed or not, a 2000 model could be either.
The ECU is matched to the chip in the key and either the CPH (non multiplexed model) or the BSI (multiplexed model). If using second hand you need the full matching set.
There are specialist companies that can either unlock the ECU or transfer the security data from yours to a used one.

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Sloppysod
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Re: Problem with my ECU. My car doesn't start.

Post by Sloppysod »

Hi "King", this is a costly lump of electronic to say its broke. what does it not do? yes you say it will not start but what else?
  • activate the 'choking' device?
  • Anything noticibly difernent the last time it did run
  • What's changed since it did not run
  • Does it activate the fuel pump?
  • Does it fire but not run?
I could go on but you know where I am going.
Good luck

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CitroJim
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Re: Problem with my ECU. My car doesn't start.

Post by CitroJim »

Before going any further you would be well advised to have a diagnostic carried out... It may well give a good clue as to the issue...

It is likely the ECU is fine and it's something external such as the fuel pump or ignition coil and injectors not receiving power...

Unless it's been subject to a severe shock or trauma such as connecting the battery reverse-polarity repeatedly it's unlikely to be faulty.

Or a sensor not giving the correct information to the ECU... For instance, if the coolant temperature or TDC sensor is faulty this will prevent a start.

Can you hear the fuel pump run when you first turn on the ignition and attempt a start?

Does the immobiliser warning lamp extinguish?

King222
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Re: Problem with my ECU. My car doesn't start.

Post by King222 »

Sloppysod wrote:
25 Jan 2021, 16:49
Hi "King", this is a costly lump of electronic to say its broke. what does it not do? yes you say it will not start but what else?
  • activate the 'choking' device?
  • Anything noticibly difernent the last time it did run
  • What's changed since it did not run
  • Does it activate the fuel pump?
  • Does it fire but not run?
I could go on but you know where I am going.
Good luck
activate the 'choking' device?
I don't even know what is that, sorry.

Anything noticibly difernent the last time it did run?
Yes, I had some problems with my battery and finally my battery went flat but before I replaced it for a new one I had some problems with the power. Sometimes the car didn't give me the power when I accelerate at the beginning of the ride, first gear but I thought it was the battery because during those times I had problems starting the car because of my battery. I know, I should have replaced it earlier. Anyways I replaced the battery and everything was fine but the last day I had the same exact problem with the power, I stopped the car and then I couldn't start it anymore.

What's changed since it did not run?
Crankshaft sensor.
Battery.
Ignition coil.
Spark plugs.
A mechanic checked everything and he said it must be something related with the ecu but he couldn't do nothing because he doesn't have the equipment to do it. He even checked the injectors.

Does it activate the fuel pump?
Apparently yes, but the pumping is not strong enough I guess. Actually another mechanic started it actually, he oppened some tube right in the motor, and putting gas while trying to start it with the key it worked. That's the only way he could start it.

Does it fire but not run?
It tries to start but it doesn't. Like you can hear the noise that all the cars makes when you turn the key but it doesn't start, the motor doesn't start. Sounds something like this:
Last edited by King222 on 25 Jan 2021, 19:14, edited 2 times in total.

King222
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Re: Problem with my ECU. My car doesn't start.

Post by King222 »

CitroJim wrote:
25 Jan 2021, 18:18
Before going any further you would be well advised to have a diagnostic carried out... It may well give a good clue as to the issue...

It is likely the ECU is fine and it's something external such as the fuel pump or ignition coil and injectors not receiving power...

Unless it's been subject to a severe shock or trauma such as connecting the battery reverse-polarity repeatedly it's unlikely to be faulty.

Or a sensor not giving the correct information to the ECU... For instance, if the coolant temperature or TDC sensor is faulty this will prevent a start.

Can you hear the fuel pump run when you first turn on the ignition and attempt a start?

Does the immobiliser warning lamp extinguish?
Well I had some problems with my battery, it went flat and I had to replaced it for a new one. A mechanic checked the ignition coil, spark plugs, cranckshaft sensor and more and he told me it must be something related to the ECU.

How the immobiliser warning lamp look??

And the sound that makes it's something like this:

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CitroJim
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Re: Problem with my ECU. My car doesn't start.

Post by CitroJim »

The high-pitched sound in the background suggests the immobiliser is not being disarmed...

Did your mechanic run Peugeot-specific (not a generic code reader) diagnostics on the car?

Unless this has been done, it's all guess work and poke 'n' hope ;)

If not, please arrange to have this done... It will save time and much frustration :)
Last edited by myglaren on 26 Jan 2021, 10:04, edited 1 time in total.
Reason: Predictive text error corrected/

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CitroJim
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Re: Problem with my ECU. My car doesn't start.

Post by CitroJim »

King222 wrote:
25 Jan 2021, 18:52

Does it activate the fuel pump?
Apparently yes, but the pumping is not strong enough I guess. Actually another mechanic started it actually, he oppened some tube right in the motor, and putting gas while trying to start it with the key it worked. That's the only way he could start it.
Then that may suggest a failed fuel pump or a blockage in the fuel lines if it is incapable of correctly pressurising the fuel rail. As your mechanic to test the fuel pressure in the fuel rail. It should be around 2.5 bar...

Has the fuel filter been check and eliminated as a potential cause?

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Sloppysod
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Re: Problem with my ECU. My car doesn't start.

Post by Sloppysod »

The "activate the 'choking' device?," was referring to the fuel enrichment device, I old I think of it a .choke'
Anyways, I agree with Jim as the symptoms you had before it stopped does sound of fuel starvation.
Also, "Apparently yes, but the pumping is not strong enough I guess. Actually another mechanic started it actually, he oppened some tube right in the motor, and putting gas while trying to start it with the key it worked. That's the only way he could start it." it would suggest the ECU is not a fault as it started. the sound tracks sound as if the car is spinning over happily, so battery it okay
As for Jims comment "Can you hear the fuel pump run when you first turn on the ignition and attempt a start? ", As a simple check to see if the Fuel pump is working yourself sit in your nice an quiet then turn the ignition on, DO NOT TRY to start, you should hear a whirring noise for about 5 seconds, its not loud so listen carefully.

Good luck

King222
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Re: Problem with my ECU. My car doesn't start.

Post by King222 »

Sloppysod wrote:
27 Jan 2021, 13:25
The "activate the 'choking' device?," was referring to the fuel enrichment device, I old I think of it a .choke'
Anyways, I agree with Jim as the symptoms you had before it stopped does sound of fuel starvation.
Also, "Apparently yes, but the pumping is not strong enough I guess. Actually another mechanic started it actually, he oppened some tube right in the motor, and putting gas while trying to start it with the key it worked. That's the only way he could start it." it would suggest the ECU is not a fault as it started. the sound tracks sound as if the car is spinning over happily, so battery it okay
As for Jims comment "Can you hear the fuel pump run when you first turn on the ignition and attempt a start? ", As a simple check to see if the Fuel pump is working yourself sit in your nice an quiet then turn the ignition on, DO NOT TRY to start, you should hear a whirring noise for about 5 seconds, its not loud so listen carefully.

Good luck
Thanks for the response.

So the way I can hear that noise is to turn the key one time and then I turn it another time as if I'm trying to start it but I only turn it for about one second or even less and then I should be able to hear that noise for about 5 seconds. Am I right????
I'm asking you this because I checked it by turning the key only one time when you can see the lights on in the board and I didn't hear that noise at all.

So if the mechanic was able to start it that way (helping with the gasoline) that means is not the ECU or the immobiliser?? that's for sure?

King222
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Re: Problem with my ECU. My car doesn't start.

Post by King222 »

CitroJim wrote:
26 Jan 2021, 08:10
King222 wrote:
25 Jan 2021, 18:52

Does it activate the fuel pump?
Apparently yes, but the pumping is not strong enough I guess. Actually another mechanic started it actually, he oppened some tube right in the motor, and putting gas while trying to start it with the key it worked. That's the only way he could start it.
Then that may suggest a failed fuel pump or a blockage in the fuel lines if it is incapable of correctly pressurising the fuel rail. As your mechanic to test the fuel pressure in the fuel rail. It should be around 2.5 bar...

Has the fuel filter been check and eliminated as a potential cause?
Thanks for the response. I checked the fuel pump and I'm not able to hear that fuel pump sound, at least by turning the key on when you see the lights on in the board I don't hear that fuel pump at all, I wasn't trying to start it.

Should I check the fuel filter anyways?

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Sloppysod
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Re: Problem with my ECU. My car doesn't start.

Post by Sloppysod »

The pump may be well insulated so I would get your ear nearer the fuel tank. Failing that, there is a messier way, disconnect the fuel line from somewhere in the engine bay, ideally the flow and not the return, then holding the loose end of the pipe in a container get someone else to turn the ignition on do not try to start, you should see fuel flowing.
Be very carefull when disconnecting the fuel line as it maybe under pressure, which is a good thing!

............and yes while you are there check the fuel filter, these don't typically get replaced as often as they should.

King222
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Re: Problem with my ECU. My car doesn't start.

Post by King222 »

Sloppysod wrote:
28 Jan 2021, 17:16
The pump may be well insulated so I would get your ear nearer the fuel tank. Failing that, there is a messier way, disconnect the fuel line from somewhere in the engine bay, ideally the flow and not the return, then holding the loose end of the pipe in a container get someone else to turn the ignition on do not try to start, you should see fuel flowing.
Be very carefull when disconnecting the fuel line as it maybe under pressure, which is a good thing!

............and yes while you are there check the fuel filter, these don't typically get replaced as often as they should.
Fuel pump is definitely not working guys that's for sure. So knowing that, what's the next step??? That means the problem is not the ECU??

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CitroJim
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Re: Problem with my ECU. My car doesn't start.

Post by CitroJim »

King222 wrote:
03 Feb 2021, 14:17
Sloppysod wrote:
28 Jan 2021, 17:16
The pump may be well insulated so I would get your ear nearer the fuel tank. Failing that, there is a messier way, disconnect the fuel line from somewhere in the engine bay, ideally the flow and not the return, then holding the loose end of the pipe in a container get someone else to turn the ignition on do not try to start, you should see fuel flowing.
Be very carefull when disconnecting the fuel line as it maybe under pressure, which is a good thing!

............and yes while you are there check the fuel filter, these don't typically get replaced as often as they should.
Fuel pump is definitely not working guys that's for sure. So knowing that, what's the next step??? That means the problem is not the ECU??
Using a voltmeter or a test bulb check if 12V is reaching the pump motor... Expose the pump connector - most likely you'll find a round plastic cover (like a big black bung) under the rear seat... Remove it and you should see the top of the pump plate with two pipes and an electrical connector that carries the pump supply and the fuel gauge sender wires... The two thick ones are the pump supply...

If you see 12V then the pump is likely faulty...

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Paul-R
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Re: Problem with my ECU. My car doesn't start.

Post by Paul-R »

This sounds the same, or similar, to the problem I had with our 2000 Xsara back in 2012. I had suffered intermittent refusal to continue running after starting. The engine would turn over, catch and then a second or two later stop.

I'll cut the very long story short and say that I eventually cam to the conclusion that the BSI was at fault as it was supplying power to the pump and then failing to continue this supply. I identified the wire on the fusebox that went to the fuel pump and applying a live feed to this kept the engine running. I didn't dive into the BSI but instead I wired up an alternative ignition switched feed to this wire (I took the fuse out so there was no feed back into the BSI) through a fused relay and bypassed the problem. IIRC the wiring still had the inertia stop switch in circuit as that sits between the fusebox and the pump.

The 306 and Xsara are sisters under the skin so you should be able to do the same if you want to. I knew that the fuel pump was not at fault as it had been replaced the previous year.