Cooling Fans - Whats the problem ?

[Bob the Planner]

I have a poblem with the cooling fans - They don't seem to be kicking in.

I have got the engine to 96C on the dash but still no fans. At this point I turned the engine off and left everything cool down. I have then removed the air box and disconnected the ECU water temp sensor. The off side fan comes on with the water temp connector disconnected but the near side one does not fire.

Any idea how I fix :
a) the offside fan not kicking in at about 92C and
b) why the nearside fan does not appear to work at all

Any recommendations or diagnostics would be usefull

Bob

[Druid]

(a). Possible sensor fault
(b). Wiring fault. Quite often corroded connections at the fan end.

[Bob the Planner]

Removing the connector should erradicate the sensor issue as far as I understand it. May need to look into the connectors. Given that the off side fan works with the connector removed probably means I have a sensor problem but the near side one is maybe a connector issue.

[nrick]

Corroded plugs on the fans, or the second fan is us. Might also be a relay?

[Bob the Planner]

Mmmm - how do I check the relays or connectors ?

[nawarne]

Agree with above. If, when you disconnect - with engine running - the ecu sensor, btwn cylinders 4 & 5 the fans don't run, then my next check would be the fan connectors. After that, if you still haven't got 12V at the connectors, I'd be looking at fuses and relays. My 2p worth.
Nick

[Druid]

Also your dash display might not equate to the ecu sensor reading. If you can plug the laptop in to confirm readings and to check if the fans are indeed switching.

Why not let the engine get a little hotter to check the the good fan comes on.

You could swap the fan connectors to check the function of the non running fan when you disconnect from the sensor. Whilst unplugged give them a clean with a rolled up piece of emery cloth.

[RedSpike66]

Just replaced faulty relay for offside fan on my Sag. Sounds like you could have faulty relay or blown fuse for the nearside fan, if the cabling checks out ok. Do you have Graham Varley's Sagaris manual with the picture of the fuse box detailing the relay positions ?

If not, Fan1 is the first yellow relay nearest the top of the steering column. Top LHS as you look at it. Fan2 is bottom RHS I think.

Relays are about £5 from Racing Green

[Bob the Planner]

Had not thought about the relays, the fuse checks out OK - or at least the one in the owners manual.

I will try swapping the fan connectors over and see if I still get only one running - that will check out the wiring !

Relays from Racing Green would be nice but currently in NSW to may have to see what the local dealers have.

[nrick]

Don't think there is anything special about the relays, should be able to pick up locally. The fans are quite high load and the plugs are next to useless.

[nawarne]

Yeah, what Neil said, relays are standard 4 pin 30A relays. Probably get them from your local motor factors or motor electrical place for a couple of quid.
Nick