What to check before sending an ECU for repair

Modules are frequently removed and sent away when the underlying fault was outside them. A short list of checks first saves time on both sides.

Worth checking first

• Battery voltage and condition under cranking load
• Earth points - corroded or loose earths cause a remarkable range of symptoms
• Supply fuses and relays feeding the module
• The connector itself: pushed-back pins, corrosion, moisture
• Wiring near known chafe points and previous repairs
• Whether the fault codes point consistently at one circuit

What to send with the unit

The more context that arrives with the module, the faster it can be assessed: the symptom in plain terms, the fault codes read, what has already been replaced, and whether the vehicle has had recent electrical work or a jump start.