C5 2.2HDi Won’t Start

[jwalshe]

Hi all!

2002 Mk1 2.2 HDi. Car locks and unlocks etc but turn the ignition on and it makes a loud buzzing sound from the BSM and the engine won’t start.

I’ve replaced the BSM with a known working item and it’s the same. Loud buzz.

Any ideas? I’m absolutely gutted as I’ve just managed to get the car back on the road at some cost.

Thanks in advance. Any advice appreciated.

James

[citroenxm]

Just to add. Disconnecting the engine ecu and the bsm doesn't buss.. Its like a loud relay chatter really fast..

[wheeler]

Does the engine turn over? Buzzing & chattering relays are often a sign of low battery voltage but you haven’t mentioned about battery condition.

[citroenxm]

It turns over fine.. Battery has been charged..

[jwalshe]

The battery is quite old but I recharged it fully last night and the engine turns over fine. Plenty of juice in it.

[citroenxm]

Here. Have a listen..

[citroenxm]

The buzzing is related to fuel pump priming. Removing F2 for fuel pump stops the buzzing..

But there's still no communication between bsi and engine ecu..

[wheeler]

Strange one. What is the history of the fault? did it cut out when driving or just not start one day? what was the recent work done on the car?
Is there 12v a fuse 2 when the buzzing is happening?
If there is no communication with the engine ECU then the first thing you need to do is check the power supplies & earths at the ECU. A good starting point for that would be to check all the fuses (remember the maxi fuses under the BSM).

[jwalshe]

Fuses all checked and they're fine. I had moved the ECU up and back, in order to check the heater box relay (I had the squiggly amber warning light on the dash, which was lit up along with the ESP light) and when I came to reconnect the battery, I got a large puff of smoke from the positive lead. Not sure if that is relevant but having replaced the BSM, I wonder what will happen if I just bite the bullet and replace the BSI and ECU now.

[wheeler]

Have you shorted the ECU casing on the glow plug relay positive? Check for scorch marks on the casing. It's easy do do this if your not careful. Try Adding a earth from the ECU casing straight to the negative terminal & see if it starts.

[jwalshe]

I just took your advice and, incredibly, there was no horrible buzzing noise and the car started. I was speechless. Thank you so much! Just so bowled over, I barely have the words!

[citroenxm]

Great stuff wheeler would never of thought of thay. Fantastic advice and knowledge..

[jwalshe]

Whoever you are, wherever you live, when the pandemic is over, the tea and cake is on me!

[wheeler]

Result!
I have rectified this fault quite a few times over the years when people have done this but i have never seen it do the buzzing fusebox thing.

[GiveMeABreak]

Great result