This is causing me grief at the moment, Non start, no coms to ECU most other modules report no coms to ecu, some also report network error.
UCH reports immo info correct and ecu not locked.
Ign and earths correct at ecu but management relay not being pulled in on plug B pin k1.
CAN signal is not the cleanest ive seen but not the worst either. Not sure if this ecu needs the correct can to power up and talk or if I have a faulty ecu.
So I found a 2nd hand ecu, expecting it to power up and say immo signal incorrect, but it behaves the same way ie no coms and not switching management relay.
Using the snapon scope powering from its own battery the CAN at breakout box and ecu looks correct untill the 12v lead is used to power the modis, then the two traces rise by 2 volts and become distorted?? same if the dl16 is used to power the modis?
Sorry for length, can anyone confirm if these ecu s Siemens sid301, will or will not power up with a missing or poor immo signal on the CAN?

Hi Andy,
Don't know if this will help but we have loads of Renaults in with various non start and com errors and 9 times out of 10 its the wiring in front of the battery which is the main loom to the fuse box is the fault usually water ingress. Worth checking.
Neil

Did look there earlier, but Should be able to measure what is missing at the ECU were it a wiring issue I would have thought anyway.
Going to power it up on its own and see if it talks next week.

Hi

Small orange wire that runs from underbonnet unit to engine ecu breaks.

Its the one in the loom under the felt pipe in front of battery

Cut tape off and give thin orange wire a tug, usually snaps

Mark

The small orange wire as you are both talking about, is the switched earth from the upc managment relay to the ecu. It measures and tests as fine, and if triggered at the ecu does bring in the relay.
I have both these ecus on the bench and cant make them talk there either,
Couldnt get on renault site today to check diagram against AD

Could it be engine firebox at fault?

I had a Megane earlier this week can looked a little out.
And modules reporting no comms and no comms to engine

Found green pins on engine fuse box.

Fired straight up with another fusebox.

I could be wrong here but.

I believe the ecu is woken by the uch on pin D1 C connector, which the pulls the relay on K1 like you say, that then supplies power to the ecu.
Can you backprobe the K1 with ignition off, you should have a voltage through the relay solonoid. Last one I did was a faulty fuse box, if it's the one I'm thinking of that has the relays built in and are troublesome.

Also have you tried to supply an earth to that terminal to see if it switches the supply.

Well. Renault site has diagram wrong which means AD is also wrong They have Cd1 as a connection to a flap motor and not an ignition supply.
When I used that pin as the 15 in then I have coms on the bench and CAN is back. Thanks Chris.
The relay isnt pulled in but I suspect it needs the immo signal to let it do that, have not pulled car in yet to look at Cd1.