How to repair a “fried” 200/400/600 ECU.
These ECU’s are prone to voltage spikes or being fried by accidentally touching the ECU case with a spanner whilst disconnecting the battery (200/400 models). If this occurs the ECU can display random things on the dash dials and the engine will not start at all.
Most garages will tell you that this requires a new ECU which will be expensive and will need programming with the alarm ECU in order for it to work which is all very expensive. However this often isn’t necessary and a DIY repair can often be made.
What happens is that the earth supply to the ECU is fried when the voltage spike or accidental short circuit happens. This causes the ECU to get very upset and so it goes on strike. 3 courses of action are open to you.
- Get a new ECU or send the ECU to someone to repair
- Open up the ECU, locate the burnt out track on the PCB and repair it with some wire and a soldering iron
- Try adding a separate earth wire from the battery negative terminal to the metal ECU casing. (The ECU can then use this to complete the power circuit)
Obviously 3 is the easiest and fastest and often works, so it is probably the one to start with. Its very useful to remember if you are stuck in a car park with a duff ECU and no AA/RAC/etc cover!
If this tip helps you out remember where you heard it, and if you meet me I accept gifts of cider!