cooling fans
Le Mans Master
Joined: Feb 2005
Posts: 6,479
Likes: 565
From: Clearwater Florida
..... The simplest way is to locate the trigger wire on the fan relay (the ECM grounds the relay ... green wire on most C4's) and wire in a toggle switch without eliminating the wire from the ECM (tap in) ... that gives you manual control with ECM fail safe back-up lest you not notice your temp gauge when on manual control ... Orrr , you could permanently ground the relay and have engine cooling fans running any time the ignition is on ... If your relay is junk , get a new one with a new connector/pigtail .....
Team Owner
Joined: Sep 2003
Posts: 25,385
Likes: 2,737
OP - What set of circumstances leads you to believe you need to manually control these FANS?
The '90 is the first year for 2 fans controlled by ECM and a "pair" of relays, the set of circumstances for operation of "either or both" are somewhat complicated but a functioning cooling system and proper fans and relays are generally felt to be the desired!!
The '90 is the first year for 2 fans controlled by ECM and a "pair" of relays, the set of circumstances for operation of "either or both" are somewhat complicated but a functioning cooling system and proper fans and relays are generally felt to be the desired!!
