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Old July 10th, 2010, 17:13
carves carves is offline
NAXJA Forum User
Join Date: Apr 2010
Location: Australia
Posts: 243
Re: Radiator Fan Override Switch (The Easy Way)

Originally Posted by kastein View Post
You're partially correct. The ECU does switch the relay on by grounding the terminal - but what you're missing is that the ECU will notice if you ground the same terminal by yourself. It'll throw a CEL saying that the fan relay is stuck low for some reason.

What this mod does is turn the relay on without forcing the ECU fan relay control wire to ground, so the ECU never realizes you're doing anything.
actually ......

I've got a 97/98 update .....

My over-ride for the e-fan is no more than a splice into the blue/pink wire at the PDC ... and a switch that grounds the spliced wire.

No relays / diodes or anything else ... and it works a treat if I ever need to turn it on.

Theres a writeup on jeepforum that confirms it ... altho many have the CEL as you mention - depending on year models.
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