cossie fan wiring
04-04-2011, 04:17 PM
#1
Glennvestite
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cossie fan wiring
Hi people. Ive had my saff 4x4 cossie for over 5 years now. I know they have problems with the fan wiring on cossies. Ive noticed a few times that the 30 amp fuse in the fuse box has looked all melted. The car has never overheated till last saturday when the wife had the car lol. The fuse had popped causing the car to look like tomas the tank engine when she pulled up lol. I take it over the years the wiring just degrades a bit. Is there anyway to repair the wiring is it just easier to get a modified fan loom liked msd sell. Ive drove the car to and from work and the head gasket hasnt gone by the way.
04-04-2011, 05:49 PM
#3
The loom was sub standard to start with leave alone now! The main problem is the span of the switch, it brings the fans on to early then keeps them on for agaes, which causes the fuse to melt.
The problem only arises when stood still for a period in traffic etc if you don't have no fans, I am surprised it has never overheated as the temp rises rapidly when they are still, obviously when moving the fans are not required.
You can buy looms pre made or DIY, basically rewire, diden't know MSD sell the looms but they do "Sell" uprated switches.
Another thing to look at is the fuel pump wiring, this builds resistance over time and the pump cannot draw the power it needs thus you do not get the required fuel delivered!
Martin
The problem only arises when stood still for a period in traffic etc if you don't have no fans, I am surprised it has never overheated as the temp rises rapidly when they are still, obviously when moving the fans are not required.
You can buy looms pre made or DIY, basically rewire, diden't know MSD sell the looms but they do "Sell" uprated switches.
Another thing to look at is the fuel pump wiring, this builds resistance over time and the pump cannot draw the power it needs thus you do not get the required fuel delivered!
Martin
05-04-2011, 04:31 AM
#5
MSD do now sell Fan looms.....
I would personally look to re-wire the std set up.
My fans, fuse, wiring and everthing else on there have been perfectly fine and I've never had any problems.
Fans simply cut in and back out in a matter of around 1 - 1.5 minutes
I would personally look to re-wire the std set up.
My fans, fuse, wiring and everthing else on there have been perfectly fine and I've never had any problems.
Fans simply cut in and back out in a matter of around 1 - 1.5 minutes
05-04-2011, 08:53 AM
#6
The loom was sub standard to start with leave alone now! The main problem is the span of the switch, it brings the fans on to early then keeps them on for agaes, which causes the fuse to melt.
The problem only arises when stood still for a period in traffic etc if you don't have no fans, I am surprised it has never overheated as the temp rises rapidly when they are still, obviously when moving the fans are not required.
The problem only arises when stood still for a period in traffic etc if you don't have no fans, I am surprised it has never overheated as the temp rises rapidly when they are still, obviously when moving the fans are not required.
This is absolutely correct. The fans draw massive current that the fuse box and wiring wasn't really up to when new.
I suspect the harness is the same as the single fan standard Sierra system and wasn't really engineered to suit the Cosworths twin fan setup.
Rewiring them direct to the battery has one massive advantage on top of the fact the fans are now reliable, it pulls a lot of load out of the fusebox which stops the grim idle some cars have when the fans come on.
The YB fuse box really is massively overloaded on some cars.
You can find the looms in the Cosworth section of our web shop here:
Last edited by Stu @ M Developments; 05-04-2011 at 08:55 AM.
05-04-2011, 09:32 AM
#7
When you consider that this feeds the heated rear screen, heater motor, all lights, radiator fans, wiper motor, engine ECU and fuel pump, etc, etc, I was surprised the car didn't catch fire!
Suffice it to say that I've re-wired the fuse box with more suitable cables - a 8.5mm^2 and a 10mm^2, and taken the rad fan feed and fuel pump feed out from the fuse box.
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07-04-2011, 12:28 PM
#13
Very simple circuit wise, a good diagram in red on here, a feed from the battery with suitable gauge wiring, via a fuse of course as close as possible to battery, to a relay and from the relay to the fans, another feed for the relay (Doesn't have to be heavy duty wire) and use the fan switch to negatively trip the relay, akin to the OE setup 
Some go one step further and have a relay for each fan.
The trouble is the switch is one of the main problems as it keeps the fans on for sooo long so really you need to "Uprate" this as well.
Martin
Some go one step further and have a relay for each fan.
The trouble is the switch is one of the main problems as it keeps the fans on for sooo long so really you need to "Uprate" this as well.
Martin
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