Planning the next
AO Silver Member
Join Date: May 2007
Location: United Kingdom
The relay will be marked with moulded in numbers.
There'll be two marked 85 & 86. These are the coil. Pins 85 & 86 will have a Light-Blue/Red wire on both fan relays. This is ignition switched +12v for the coil. The other coil terminal ( 85,86 ) will have a Red/Green wire the 2nd speed relay and Pink/White on the 1st speed relay. Those wires go to the engine ECU and will be earthed there in order to energise the relay when the ECU determines the fan(s) are needed.
The relay will also have terminals 30, 87 and 87a. On both fan relays, 87 should have a black wire to earth. 30 should have a White wire on the 1st speed relay and a Brown wire on the 2nd speed relay. The wires on 30 & 87 may be the other way around. 30 is supposed to be the input but AR will often do it the other way! It doesn't matter.
That's all that's needed. If the relay has a terminal 87a, you don't need to worry about it not being connected as it is commoned inside the relay with 87. This arrangement is used with the fog light relay for example, where 87 goes to the lights and 87a goes to the dashboard warning light.
This probably answers your question about the colour of the relay as well. As long as the relays are rated 50Amp for 2nd speed and 30Amp for 1st speed, and the four wired terminals in the holder match terminals 85, 86, 30 and either 87 or 87a, all is good.
The behaviour of the fans when you disconnect the sensor is normal. The ECU won't command the fans to go straight into 2nd speed. It'll accelerate them.