Problem blowing fuse f1 30a which feeds fuel pump relay,main feed from battery feeds relay via 30a fuse,then splits at relay feed to ecu pin 18.Fuse keeps blowing until main connector disconnected at ecu then short dissapears,reconnect main connector and the short is back.Does appear to be an internal fault with the ecu shorting out,but could it be a sensor short circuiting as the feed comes out of the ecu?

unable to code read as no power to ecu.

any thoughts appreciated .


Neil

If it still blows the fuse with the fuel-pump relay removed then, surely, it has to be in the ECU?

Re-fitting the plug might be activating the relay for a few seconds, temporarily feeding things like the injectors [unlikely to be a short] and more hazardous things like the Lambda probe's heating coil.

You could also try unplugging the power-steering switch and the can-purge valve.  Both a long shot; but quick.

Only one way to prove it.  Have you got a meaty ammeter [clamp or in-line] to test the ECU's earth connexion for a big pulse of current when this blows?  [Or fit a lower fuse in it?]  If it's earthing down the ECU's earth cable; then it's time to call BBA.

[I have heard of dealers changing a lot of engine looms on Clio 2's - mainly 16v ones; probably not relevant, but...]

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thanks for the reply.the short has stopped now but ecu is not

talking/playing does appear to be an internal fault ,difficulty in checking pin data as on auto data pin data it doesnt diferentiate between sagem and magnetti marelli

will check sensors as you advise especially lambda before fiiting new ecu.

thanks


Neil

Don't you just love it when the short goes away when you don't want it to!

Try fitting an in-line fuse into the ECU's earth connexion anyway.  10/15 amp should do.  Then, if that suddenly blows, you know it was through the ECU.

If you need any pin numbers; the wiring diagram for the Sagem ECU one [of four!] is on the CD.  [At least it shows where everything connects.]  I'll be back later.

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Had one of those recently where a garage had fitted a new lambda sensor after plugging it in so the wiring was very badly twisted. This lead to the wiring breaking and then shorting. It's worth checking the wiring ar the sensor (although having thought about this further I think lambda is fed from fuel pump relay). HTH

Regards, Ian.

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Experience is something you don't get until just after you need it!

have plumped for the ecu faulty but def going to test the lambda before fitting new and the smoke appearsand £450 down the swanny.

cheers


Neil

the murky waters are getting murkier

have checked the usual suspects on the wiring loom.

have sent the ecu for checking and see what the report brings.

thanks


Neil

Thanks for the replies.

Internal fault in the ecu .Repaired.


Neil