ECU getting intermittent power

[Andymoor24]

Hi guys,
Currently tracing an electrical gremlin where my EML, ignition on engine off, is randomly flickering. When it’s a warmish day, the light stays mostly only, but often turns off, flickers, etc. On a cold day, it’s the other way round; light mostly off, flickering on randomly.

The engine will not fire with the EML off, but will with the EML on, but then cut out at random, because of course the ECU looses power as above.
So I have the wiring diagrams and loom diagrams for my model (1.4 coil pack model) and have been trying to trace the fault to find a corroded connection or blown fuse, etc, but no luck so far.

Am I missing anything monumentally simple here?

I have already:
Changed ignition switch
Replaced battery
Cleaned cable terminals for battery
Swapped temp sensor
Swapped TPS
Removed dash to access all cables
Checked for blown fuses
Replace fuse board (fuse 24 had a melted, poor connection)
Cleaned both body grounds on O/S wing and N/S interior ground. Hard to access the others.
Tested related pins for voltage on ECU

 

[fuzzy-hair-man]

Hi guys,
Currently tracing an electrical gremlin where my EML, ignition on engine off, is randomly flickering. When it’s a warmish day, the light stays mostly only, but often turns off, flickers, etc. On a cold day, it’s the other way round; light mostly off, flickering on randomly.

The engine will not fire with the EML off, but will with the EML on, but then cut out at random, because of course the ECU looses power as above.
So I have the wiring diagrams and loom diagrams for my model (1.4 coil pack model) and have been trying to trace the fault to find a corroded connection or blown fuse, etc, but no luck so far.

Am I missing anything monumentally simple here?

I have already:

On the earlier dizzy engine there's an ecu relay (green) that turns on the power to the ecu, is suggest seeing if that's working. It's located in one of the engine bay fuse boxes yours may be similar.

 

[Andymoor24]

On the earlier dizzy engine there's an ecu relay (green) that turns on the power to the ecu, is suggest seeing if that's working. It's located in one of the engine bay fuse boxes yours may be similar.

Thanks for the suggestion - I have checked that it definitely clicks with the key in ignition and when the EML light flickers, the relay remains in a closed state. Power getting to the relay obviously isn’t an issue in that case, however power coming from the relay has also been tested. Getting voltage at the connected ECU pin. I haven’t tested that line for resistance though, to check for a broken wire, but I have checked every connection and connector following those wires from the relay to ECU (G/W and W/G wires)

 

[Andymoor24]

Well, in the end, turned out to be the ECU itself. Must have a dry connection somewhere, but that’s beyond my expertise and it doesn’t seem like any company I speak to is willing to fix it!

 

[fuzzy-hair-man]

If you find a computer repair or electronics store or something like that they will probably know someone that could have a look for you. Yours would be a NATS anti-theft system so you can't just swap ECUs.

 

[Andymoor24]

If you find a computer repair or electronics store or something like that they will probably know someone that could have a look for you. Yours would be a NATS anti-theft system so you can't just swap ECUs.

Appreciate the input - I’ve been looking but nobody local fancies helping and every “ECU repair” company turning their cheek to mine. Either way though, I have swapped the ECUs and IMMOs, reprogrammed keys and it’s all working no worries. Waiting on the arrival of a 1.4 ECU and IMMO now so I can take out this 1.0L ECU kit and it’ll be running as it should.