High resistance on ECU relay output

We was tasked to diagnose a Vauxhall Corsa E crank no start. As such we fully scanned the vehicle for codes and there were a few relating to the ECU, many would simply send the ECU off to be tested. However we carried out a few checks and found one of the ECU circuits wasn’t turning on the ECU relay, this other ECU relay switches on the power supplies for the coils, o2 sensors, EGR and much more. As such will these items not being commanded to turn on the vehicle won’t start. We confirmed our diagnosis by bypassing this relay and the vehicle started straight away.

We needed a OE diagram to repair this fault quickly without taking hours, as such we managed to get an OE Vauxhall guide and confirm the correct pin numbers at each end ( engine bay fuse box and the vehicles ECU ) once confirmed we found this wire had a very high resistance. We stripped down the loom and found this single wire had a tiny hole in the wire and it filled up with water and as such rotted out the internal copper within the wire.

These types of repairs can run mechanics around in circles without the correct wiring diagrams and electrical experience. As such we was called in to diagnose and put it right. We managed to fix this issue within a short amount of time and save the customer a major amount of money. Call 07340 341790 for all your auto electrical requirements.