Radiator fan not coming on problem (R500K)

[rj]

And you're sure he didn't change anything from when he built it?

In fact, Minister could have added it as part of maintenance.

[anthonym]

it was built and maintained my Hyperion Motorsport, the sole Caterham Motorsport agent of the time, and run as the owner's private track car for 18 months (iirc) and 1800 miles, (I view this period as road testing :-)   )   with every upgrade being applied as it became known (this was the time of the "unreliable R500" with a reputation for destroying itself due to an oil problem, so the only extra I do not have seems to be a laminator. Was this "upgrade" after the original build or not? Who knows. Minister was not involved until I took it there for the first refresh (and more engine upgrades - sadly not the CRA). I've forgotten why this matters... I don't yet know whether I have a fan relay, though I do have a relay fixed to the bulkhead in the location shown in one of the images in this thread, so I hope I have a relay. It's a bit nippy (sub zero) in my garage for much delving and how to identify pin 33 in situ is something I am wondering about, so I could follow where it goes. Do we know what colour it is?

[mark_w]

hoping to get on and work on this over the weekend, i was a bit surprised that my relay set up on the bulkhead is quite standard on the R400 / 500  cars  but mine is wired with orange wire from pin 33  do you still have the mbe as thought you mentioned emerald   there is a guide on here that mentions K3 using pin 6 for the relay but on mine i unplugged and took the plug apart exposing all the wires and found the numbers moulded in around the wire entry points. 

i have seen now relays with built in fuses so might be a tidier solution

[rj]

I wrote this in reply to Anthonys post believing it was a PM and before I had seen Marks last post. Orange it is, then...

 

I don't have a diagram for it and though I once bought one I don't know where I've put it. Surely somewhere safe.

ISTR there was an orange wire but it may have been 8 years or so ago(!)

Just pull the relay and short the terminals for the contact (30 and 87) NOT NOT NOT anything even near 85/86 as this will blow the ECU if it's connected like we think.

It may very well be a Hyperion upgrade. Steve knew how to run the race cars, and I would not be surprised if he'd suggested this.

 

/r

[anthonym]

mark do you need/like pics of mine? 

sorry didn't mean to disappear.

anthony

[mark_w]

Hi All,  so my fan is wired directly to the battery  so need to correct this by wiring to the kill switch or ignition maybe ?

on the ecu control side of things its wired

ecu pin 33 to connector 86 on relay--- connector 30 on relay to 25A fuse to battery -ve--- connector 85 on relay to battery -ve

with connector 87 on relay disconnected

questions are the 25a fuse is on the earth wire , is this correct?

how would i wire the override switch in

do i take the fan +ve blue wire to connector 87 on relay

Ian's diagram post 43 shows going to the +ve side through the ignition switch where mine is wired to the -ve side 

 

 

[Jonathan Kay]

"Standard" relay terminals.

Jonathan

[mark_w]

does it look like i have the two wires going to the -ve battery that should go to the +ve side through the IGN switch just trying to follow Ians post 43 diagram, maybe the two wires have been put to the wrong side of the battery at some point by mistake 

[anthonym]

I’ll see if I can see what mine does a bit later.. bit chilly in the garage around minus 7 :-)

[mark_w]

ok thanks Anthony

[rj]

If this drawing is correct the relay will never be triggered as the output of the ecu is a switched earth.

Apart from that the image is too small to see how the fan is connected, but terminal 30 usually is battery + On a car with a master switch cutting the positive supply I'd put it after the master switch.

(On my car I switch earth with a hefty relay from Brise; than IF I have a short circuit to the chassis in the event of a crash the worst thing that can happen is that the switch does not break power whereas if it's the positive that's switched, then the feed wire is rather dangerous always being live - this probably is a little paranoid as the relay is sat on the top of the battery with a very short wire. The downside of having a relay as a master switch is that it drains the battery if (when) I forget to switch off in the garage).

[mark_w]

thanks RJ. So it clear i have a lot of wiring going to the wrong places

relay 86 goes to ecu pin 33 - wrong,  relay 85 goes to battery -ve - wrong, relay 30 thru 25A fuse to battery  -ve - wrong

fan override directly to battery +ve with no fuse - very wrong

so here's my plan relay 85 to ECU pin 33,    relay 86 to battery  +ve,  relay 30 thru fuse 25A to battery +ve,    relay 87 to fan

now for the override switch use the green wire from the existing fuse No3 (rad fan) which i need to trace but hoping its disconnected i then connect to the override switch then wire on to the fan, this way I still have the manual operation for the fan until I can get the ecu temp on/off settings checked. Am i seeing things correctly here?

[anthonym]

I’m curious, why not switch pin 85 from the over-ride switch ? Do away with the rest of the over-ride circuit?

come to think of it there’s no relay in your over-ride circuit?

and 86 to battery isn’t fused; doesn’t that create an unfused feed straight to the ecu when the relay closes?

[mark_w]

Well yes always open advice on where I'm going wrong with this and what i would need to do, as my two wires ends from 30 and 86 are permanently connected to each other and go to the battery i presumed this to be how it was wired origionally if they need to be separate and 86 go through a fuse that's good advice and what I need.

as for switching to pin 85    wire from 85 to override then to earth ?

Edit:  overide to 87 on relay might be the way to go?

[anthonym]

Let’s check with rj :-)

 

Yes one wire from relay to ver-ride switch seems efficient given it’s an earth; just don’t know if that is an issue for the ecu, but seems to me if ecu 33 is not active (to earth) then there’s no issue and if it is (or becomes so) it’s merely an earth.

[Mark Durrant]

I previously owned an R500K and the fan was controlled by a thermo switch mounted in the top of the radiator similar to this. The car was also fitted with a manual override switch, Stack Dash and had the MBE ECU. I would start by joining the two wires connected to the thermo switch in the top of the radiator and if the fan comes on this is likely to be your problem.

 

 

[mark_w]

Hi Mark I don't have the normal rad thermo switch in the rad, i only have the stack temp sender  and the ecu temp sensor brown plug (post 12 pic) so a bit different to the norm   the stack sender does look very much like the thermo switch but has been a bit of a red herring

[Mark Durrant]

Mark

Have you checked the wiring loom near the radiator to see if the wiring for the fan thermo switch exists? There should be a two core wire with insulated push on female spade terminals. The two sensors in your pictures are the Stack Dash water temperature and the water temp for the ECU.

Mark

[mark_w]

Sure its there somewhere did have had a look but couldn't see anything, waiting on a wire tracer that's in the post as its the wire from fuse 3 that i was thinking of using for the override.

With the fan on/off temp controlled through the ECU

[SLR No.77]

Mark, just to add to what Mark D has said, at the radiator end there should be the 2 wires that Mark has mentioned that would be used for the original radiator temp sender, these will be 90 deg angled 6mm female spade terminals with soft rubber covers, and also check that the connection to the fan wiring is a square white 2-pin block. All these wires should exit the original loom of the car and might enable you to work out how to get back to nearer standard wiring.

The wiring on my SLR had been extensively messed with prior to me buying it and was a complete nightmare, lots of faults and difficult to trace. It had little remaining that could be called an engine loom so I decided to take it back to being standard Rover as per the original install. While the engine was out for a rebuild I took the opportunity to recreate the engine loom with all the correct colour coded wires matching the wiring diagram ... there's some errors on Caterham's wiring diagrams which doesn't help! Having got it all sorted it's now bang on reliable and tidy and I know if there are any issues I can refer to the diagrams for reference. It's worth doing it properly.

Stu.

[rj]

Ok, just so tat no-one is in doubt: I simply hate this forum. I had written a long post, then when it came to adding an image I lost it.

Anyway, what I meant to "say" was:

Be careful. On an automotive relay terminal 85 has to be the positive and 86 the negative. Some relays have a diode built in, and if you crosswire you may blow the output of your ECU. So when the ECU has a switched earth output terminal 85 has to go directly to the positive supply. The relay may not have the diode but what if you at some point changes the relay to one with without remembering this?

I would not want two fuses in the circuit as you then, if both relay and switch are on are able to drain 50 amps via your earth wire should the fan blow.

I would also fit the override swith to the primary side of the relay. You have to have a wire crossing the scuttle. If this is a switced earth, then worst case is that the fan run if you have a short circuit. (As per my own master switch relay).

I would do something like this.

Be aware that the position of the relay terminals is not correct. VW relays have a different layout than IE Rover relays.

IF you have questions and want a quicker reply feel free to send me a PM - I may not notice that there has been a new post here. Or you can PM me your phone No, then I shall do my best to guide you.

[anthonym]

finally, I have some video of my wiring, which without the over-ride and with the 85 (to my chagrin) not being fused, is the same as rj's diagram. 

yet another unfused circuit on my car, the last one was the starter.. still is for now.

I'll attach the vid when I figure it out..  includes the white block mentioned above and bulkhead relay with fuse.

[rj]

PS: My circuit will leave the fan running with ign. off. If you don't want this you could connect terminal 85 to ECU pin 13, which is the power supply for the ECU.

Always use a relay with sort of protection - that be diode or resistor!

[anthonym]

my fan often runs when I switch off the ignition.

[rj]

It will keep running until you flip the switch - or the battery is drained - if connected as in my diagram. Someone will probably say that this could over-cool the water, but is this different from the situation where the thermostat opens?

When I get around my little electronic device the fan and water pump will be able to run with ignition off but master switch off.