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

This is the Forum for all your Peugeot Technical Questions, Problems or Advice.

Moderator: RichardW

User avatar
CitroJim
A very naughty boy
Posts: 43523
Joined: 30 Apr 2005, 23:33
x 1590

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

Post by CitroJim »

Paul-R wrote:
03 Feb 2021, 19:00
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.
That is a most excellent workaround to what would otherwise have been a difficult and expensive resolution :D Top marks for that Paul =D>

User avatar
Paul-R
Donor 2020
Posts: 5170
Joined: 07 May 2009, 16:24
x 703

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

Post by Paul-R »

Cheers Jim. The fused relay came off an early Renault Espace in a scrappy. I've never seen another one like it since.

It was still on the Xsara when we sold it in Autumn 2016 and the car continued to be run locally for a few years after that. I've just checked and it passed its MOT in September 2018 but was not presented for an MOT a year later so I presume it's been scrapped.

King222
Posts: 12
Joined: 10 Aug 2020, 22:24
x 1

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

Post by King222 »

Paul-R wrote:
03 Feb 2021, 19:00
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.
Thanks for the response Paul that might be very very helpful.
So can you please explain to me how to proceed into more detail? I can identify the BSI I didn't understand much the whole process.

Also I was thinking in buying an OBD so I can get a diagnosis. Would you guys think it's a good idea??
Something like this
https://www.amazon.es/Interfaz-Bluetoot ... 0075&psc=1

User avatar
Paul-R
Donor 2020
Posts: 5170
Joined: 07 May 2009, 16:24
x 703

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

Post by Paul-R »

There's not a huge amount more I can tell you - it was a long time ago!

First, you'll need to identify the fuse under the bonnet that protects the fuel pump. I would think you'll know where that is as it should have been one of the first things that you checked. Next, identify which side of fuse is live and which goes to the fuel pump.

It may be that a 12v test lamp indicator will show which side lights up when you switch the ignition on - if it does then that shows that there is power to the fuse and my fix will not work. You need to follow the wire through to the fuel pump and find out where the problem is.

Assuming that the test lamp does not light up and you do identify which side goes to the pump then take a temporary lead from this to the positive of the battery (or a suitable point elsewhere such as the fusebox itself). The pump should then operate. If it doesn't then you'll have to follow the wire through in the same manner as the previous paragraph.

King222
Posts: 12
Joined: 10 Aug 2020, 22:24
x 1

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

Post by King222 »

Paul-R wrote:
08 Feb 2021, 18:22
There's not a huge amount more I can tell you - it was a long time ago!

First, you'll need to identify the fuse under the bonnet that protects the fuel pump. I would think you'll know where that is as it should have been one of the first things that you checked. Next, identify which side of fuse is live and which goes to the fuel pump.

It may be that a 12v test lamp indicator will show which side lights up when you switch the ignition on - if it does then that shows that there is power to the fuse and my fix will not work. You need to follow the wire through to the fuel pump and find out where the problem is.

Assuming that the test lamp does not light up and you do identify which side goes to the pump then take a temporary lead from this to the positive of the battery (or a suitable point elsewhere such as the fusebox itself). The pump should then operate. If it doesn't then you'll have to follow the wire through in the same manner as the previous paragraph.
CitroJim wrote:
04 Feb 2021, 08:32

,
Sloppysod wrote:
28 Jan 2021, 17:16
.
It could be a faulty fuel pump relay???

User avatar
CitroJim
A very naughty boy
Posts: 43523
Joined: 30 Apr 2005, 23:33
x 1590

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

Post by CitroJim »

King222 wrote:
10 Feb 2021, 00:39
It could be a faulty fuel pump relay???
It certainly could be...

User avatar
Paul-R
Donor 2020
Posts: 5170
Joined: 07 May 2009, 16:24
x 703

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

Post by Paul-R »

The point of my mod was that the wiring from the fusebox to the pump was continuous and pump worked fine. I merely bypassed the fusebox and connection to the BSI. AFAICS, you have yet to prove the wiring from the fusebox to the pump is continuous and the pump works. This should be your next step.

King222
Posts: 12
Joined: 10 Aug 2020, 22:24
x 1

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

Post by King222 »

Ok, so the fuel pump relay is good, nothing wrong about it.

Also, I bought an ODB2 to make a diagnosis looking for errors using the app Torque Pro and it wasn't able to find a single error. Everything was fine.

That means the ECU is fine???