Issues with aftermarket intercooler fan?

Hi everyone,

Just installed a second-hand rarely used RacerX side mount intercooler kit (as per pic) but I'm having issues with the fan. On Ignition, the fan will run for a few seconds then turn off and the Vent relay in the engine bay fuse box clicks. Tried disconnecting the engine bay temp. sensor and it will run but only for a few seconds before the relay clicking and turning off again.
 
I had an auto-electrician check the system quickly and he confirmed that the fan receives power/works and that the relay tested to be fine. He's convinced its possibly ECU related as "the computer keeps telling the fan to turn off"
 
Is this a common issue when upgrading the OEM intercooler fan? Or can anyone possibly give me any advice on how to proceed?

kojab
What source are you triggering your intercooler fan relay.  Sounds a bit like it might be connected to the same relay that runs your fuel pump.

Everything is running off the OEM harness - I haven't interfered with the wiring at all. Even used a Toyota plug for the fan and connected it to the original fan harness.

Engine is a Gen3 3S-GTE if it helps. I spoke with the gentleman that sold me the kit and he recommends hot-wiring the fan so that it's permanently on with the ignition and completely bypass the relay