Offside Radiator fan has failed - Help!!

[tvr_nut]

Fired up the Griff today, and ran it round the local estate (no further, as the roads have been gritted).

Left the engine running, but noticed only the nearside cooling fan was running. The offside one was VERY tight - it had been very noisy for a while when running down (which it did much quicker than the n/s one).

But on checking for voltage, I found there was no supply to the (almost seized) offside one (test done with fan over-ride switch in the "on" position)

By swapping over the multi-pin connectors, I got the o/s fan to rotate (slowly and roughly), and the n/s one did not start.

Next stop was the fuse box. Found no blown fuses as far as I could tell (did not remove every one - too damned fiddly). But found fuse #1 was 25Amp - this must mean that only one fan is on this fuse. Removing this fuse stopped the good n/s fan from running. But where does the other one get its juice??

I looked at Fuse#3 (aircon & heated seats), and Fuse#15 (spare) in case eiher of these unused fuses may have been picked up as feed to the o/s fan - but all intact.

After reading SH's "bible" I tried the horn. It still worked, and anyway only had 15A fuse, so unlikely to have a fan on the circuit.

I then tested the electrical equipment associated with each of the fuses (as listed in the handbook) - all circuits seemed to work, implying no other blown fuses.

Thus I am at a loss as to where the supply to the offside fan comes from, and where the fuse might be!

Other information that may be relevant (to people more knowledgeable than me) is that the car has the "phased" start/stop of the fans, such that one fans starts just before the other (SH's book mentions this as a dealer fitted mod).

So - three questions really:

1) Where is the confounded fuse for the O/S radiator fan?
2) How much is a replacement fan?
3) How difficult are they to remove & replace?

Must admit, as I have a weeping leak on the radiator itself, I am tempted to pay a specialist to sort the lot out - but would rather be a bit better informed first!

Any wisdom will be gratefully received.

TVR-nut

[spend]

Did you check voltage against chassis ground or the ground at each connector ?

Dave

[tvr_nut]

spend said:

Did you check voltage against chassis ground or the ground at each connector ?

Dave

Dave,

Rightly or wrongly, I simply checked the voltage across the two pins in the "male" connector. The one to the n/s fan had 12V, and the one feeding the offside had zippo!

[unclemark123]

if your car is a late car there is a seperate fuse and relay for each fan, sounds like your fan is u/s. just had one go on my car. ive replaced both my fans as , even though only one was faulty. the standard fans a suseptable to water damage, they go rusty inside and seize, the replacment models are water tight. i have a spare good working order fan if you are interested. mark :-)

[unclemark123]

ps. they are around £110-£130 each new...eeekkkk.....

[spend]

tvr_nut said:

spend said:

Did you check voltage against chassis ground or the ground at each connector ?

Dave

Dave,

Rightly or wrongly, I simply checked the voltage across the two pins in the "male" connector. The one to the n/s fan had 12V, and the one feeding the offside had zippo!

I think you missed my point? Was that from the known good connector ground to both positive pins. You have not given enough explanation to deduce whether it is the positive or negative side of the circuit on one of the fans which is at fault.


1)....------------------------------------------------------front body bolt
2)F1 +++++++++++fuse+++relay
................+
3)F2 +++++++++++
4)....------------------------------------------------------front body bolt

If you saw 12v testing across 1 & 2, then tested across 1 & 3 the pos side is the fault
however
If you saw 12v testing across 1 & 2, then tested across 4 & 3 the neg side could be at fault

Use a combination of the 2 methods to deduce where the fault lies. You can always check the positive side by checking for 12v against the chassis (any good 'black' contact).

Dave

[tvr_nut]

spend said:

tvr_nut said:

spend said:

Did you check voltage against chassis ground or the ground at each connector ?

Dave

Dave,

Rightly or wrongly, I simply checked the voltage across the two pins in the "male" connector. The one to the n/s fan had 12V, and the one feeding the offside had zippo!

I think you missed my point? Was that from the known good connector ground to both positive pins. You have not given enough explanation to deduce whether it is the positive or negative side of the circuit on one of the fans which is at fault.


1)....------------------------------------------------------front body bolt
2)F1 +++++++++++fuse+++relay
................+
3)F2 +++++++++++
4)....------------------------------------------------------front body bolt

If you saw 12v testing across 1 & 2, then tested across 1 & 3 the pos side is the fault
however
If you saw 12v testing across 1 & 2, then tested across 4 & 3 the neg side could be at fault

Use a combination of the 2 methods to deduce where the fault lies. You can always check the positive side by checking for 12v against the chassis (any good 'black' contact).

Dave

Hmm - I think I did miss the point! There is a separate connector to each of the two fans. I just checked for a voltage between red & black pins on each of the plugs (separately).

If I get your suggestion right, you are suggesting trying from the ground of the known good side to the live of the faulty side, and then again in the way I did - so as to see which side is faulty?

Auto electrics have never been my strongest point - think I need to get back under there tomorrow!

Thanks for the tolerance!

[tvr_nut]

unclemark123 said:

if your car is a late car there is a seperate fuse and relay for each fan, sounds like your fan is u/s. just had one go on my car. ive replaced both my fans as , even though only one was faulty. the standard fans a suseptable to water damage, they go rusty inside and seize, the replacment models are water tight. i have a spare good working order fan if you are interested. mark :-)

My car is a 1996, which seemingly puts it in the "uncertain middle ground" as detailed in the Steve Heath book. There it states 1998-on as having the totally separate fan supplies. I suspect my car was a 40A #1 fuse job (the handbook states that) with some subsequent changes?

No doubt the fan is shot - very tight and rattlely and stops too quickly when the power is cut. Water damage sounds likely, as I live in Lancashire!

Just need to work out the power supply problem - pretty sure the fan siezed and the lack of supply is a fuse somewhere. Time to do some tracing of wiring & earth points I think.

[spend]

I would also not trust the fan override switch for testing... Its better to short the otter switch... A lot of people with less electrical skill (and far less care...) have been known to hack at the electrics. Take nothing for granted "Sort 1 problem ~ find another 5 "

Dave

[tvr_nut]

spend said:

I would also not trust the fan override switch for testing... Its better to short the otter switch... A lot of people with less electrical skill (and far less care...) have been known to hack at the electrics. Take nothing for granted "Sort 1 problem ~ find another 5 "

Dave

Would normally agree wholeheartedly, but I put the override switch in myself only last year (took a whole day over it too), so pretty confident that it is OK. Installed as per the instructions in the SH Griff Bible.

That said, it is easy enough (now the engine is cool!) to short out the otter switch/plug. I even have two male spade connectors joined by a couple of inches of wire for the very purpose (once bitten, twice shy).

Will try the suggested tests to ground in a bit and post back.

Sort 1 problem, find 5 more - yep, that is my usual DIY experience! Come out of it a better person at the end though.....

Neil.

Edited by tvr_nut on Sunday 11th February 10:05

Edited by tvr_nut on Sunday 11th February 10:05

[spend]

Do you mean the diagram that looks like the otter switch (cunningly labelled "Thermostatic switch" switches the power to the fan?

The real systems have the otter switch controlling a relay which switches the fans on/off (fan fuse in circuit ~ may be 1 or 2 fuses & relays). The horn fuse is the one that powers the otter switch to activate the relay coil.

If you followed that diagram who knows what you have got? (sorry Steve) There is no illustration of the control & power circuit that is how the car works. I certainly could'nt figure it out.

IMHO what you need pink (power to fan from fuse box) to led to chassis to indicate fans powered (if relay fails it wont light...) and pink/green (power to otter switch from fuse box) to o/r switch to chassis (use a switch with a led & it tells you the horn fuse is OK ~ if other led doesnt come on also the relay/fan fuse has failed)

Dave

[tvr_nut]

spend said:

Do you mean the diagram that looks like the otter switch (cunningly labelled "Thermostatic switch" switches the power to the fan?

The real systems have the otter switch controlling a relay which switches the fans on/off (fan fuse in circuit ~ may be 1 or 2 fuses & relays). The horn fuse is the one that powers the otter switch to activate the relay coil.

If you followed that diagram who knows what you have got? (sorry Steve) There is no illustration of the control & power circuit that is how the car works. I certainly could'nt figure it out.

IMHO what you need pink (power to fan from fuse box) to led to chassis to indicate fans powered (if relay fails it wont light...) and pink/green (power to otter switch from fuse box) to o/r switch to chassis (use a switch with a led & it tells you the horn fuse is OK ~ if other led doesnt come on also the relay/fan fuse has failed)

Dave

Dave,

This is starting to challenge my understanding of the Griff's wiring! I must admit that the diagram in the Bible did confuse me for a while, until I rationalised it by realising the override switch is essentially the same as shorting the otter switch, but remotely operable. Getting the LED on the column to work was the more complex bit!

My car has the system as you describe - otter switch closes circuit at the switching temp, energising the relay that then sends power to the fans. I am sure my problem lies from here on, as one fan is doing as it should.

I know the horn fuse is OK, as seem all the others in the fuse box (ref my first post).

Am just about to go out and doing some more grovelling in the garage, having done all my share of the household chores (cleaner failed to turn up again this week - I only tolerate it 'cos she's 26 and rather cute!).

[Paul V]

My car has additional relays mounted on the N/S front wing to supply one cooling fan, this takes it's power from the back of the alternator via a inline fuse, might be worth checking that a similar mod hasn't been done to yours, when you look at the wiring for both fans does it run in from the same loom or a different one?

When you checked the fuse did you test them to make sure they weren't blown as sometimes they can look ok but have a same crack which stops them conducting.

[spend]

tvr_nut said:

...having done all my share of the household chores (cleaner failed to turn up again this week - I only tolerate it 'cos she's 26 and rather cute!).

The cleaner or SWMBO ? In case of the first I'd make sure SWMBO doesnt read your topic

Booger; forget to add its odds on it will be a grounding problem as usual. BTW

Edited by spend on Sunday 11th February 14:31

[tvr_nut]

spend said:

tvr_nut said:

...having done all my share of the household chores (cleaner failed to turn up again this week - I only tolerate it 'cos she's 26 and rather cute!).

The cleaner or SWMBO ? In case of the first I'd make sure SWMBO doesnt read your topic

Booger; forget to add its odds on it will be a grounding problem as usual. BTW

Edited by spend on Sunday 11th February 14:31

Was referring to the cleaner - the wife was told the topic was all techy stuff (which it was until I dragged it down with inuendo), so of zero interest (until it starts costing money).

Latest - having done more testing I found:

Testing the good (n/s fan) connector got 12V between Black (earth) & White (live)
Testing the bad (o/s fan) connector got ZIPPO V between Black (earth) & White (live) (AS BEFORE)

then:
Testing between the good (n/s fan) connector earth and the live of the bad (o/s fan) connector, got ZIPPO volts
Testing between the bad (o/s fan) connector earth and the live of the good (n/s) connector, got 12 volts.

This seems to confirm it is not a grounding problem, but one of lack of supply to the O/S fan? Bearing in mind the fan was seized, it seems most likely (to me) that a fuse or relay has failed - is this logical?

Sadly, tracing the wires back from the fans, I find no fuses or anything else before the wires join a loom that runs across the top of the nose aperture (seems to serve the horns and lights, n/s & o/s). The whereabouts of any other fuses or other aftermarket adaptations is a mystery!

Looks like I will need professional help to get any further (which is always frustrating)!

Neil

[spend]

All the front loom is run over the NS wheel arch (earths collected & grounded at the infamous front body mount under the rad) & comes out on the left of the dash. At that point there are a couple of connector blocks which have been known to cause problems. Then it goes in 2 big loom bundles down to the back of the fuse box. The only wires you are interested in are the big solid pink ones (ooer!). If you have single relay/fuse they will be crimped to the same pin on the fusebox connector block. You may need to pop the fusebox to see how your car is wired (it may have had a later upgrade ~ but they forgot to make a note in the handbook?) If you tell me the pins the pink wires go to, I can tell you which part of the fuse box the relay & fuse is in.

I reckon you only have the following possibles:

bad wire/pin connection at fan connector
broken wire in loom between fan connector and (dash/door) loom connector
bad connection at (dash/door) loom connector
broken wire in loom between (dash/door) loom connector and fusebox
bad connection at back of fusebox
failed/missing fuse/relay cos you dont know which ones are used.


Dave

[Paul V]

If worst comes to worst and you can't find the second supply you could wire it up as mine has been, Take a live and earth connection from the back of the alternator, (make sure you fit a inline fuse within the first few inches), run in down the inner wing, connect this to a relay then take a feed off the working fan connection to switching the terminal of the relay, run the power output of the relay to the fan which wasn't working and you will have both working again. That is a last resort mind and best replace that seized fan first as well.

[tvr_nut]

spend said:

All the front loom is run over the NS wheel arch (earths collected & grounded at the infamous front body mount under the rad) & comes out on the left of the dash. At that point there are a couple of connector blocks which have been known to cause problems. Then it goes in 2 big loom bundles down to the back of the fuse box. The only wires you are interested in are the big solid pink ones (ooer!). If you have single relay/fuse they will be crimped to the same pin on the fusebox connector block. You may need to pop the fusebox to see how your car is wired (it may have had a later upgrade ~ but they forgot to make a note in the handbook?) If you tell me the pins the pink wires go to, I can tell you which part of the fuse box the relay & fuse is in.

I reckon you only have the following possibles:

bad wire/pin connection at fan connector
broken wire in loom between fan connector and (dash/door) loom connector
bad connection at (dash/door) loom connector
broken wire in loom between (dash/door) loom connector and fusebox
bad connection at back of fusebox
failed/missing fuse/relay cos you dont know which ones are used.


Dave

Dave,

Thanks for passing on even more of your knowledge of the Griff's electrical system - do you do this stuff for a living?

The thing that makes me think it is not a simple (?) wiring fault is that the O/S fan had seized, having worked only a few weeks previously. I assume such a seizure would result in a fuse/relay damage, rather than a connector type problem? Although it cannot be categorically ruled out, of course!

I must admit to hating working around the fusebox on the Griff - all the bits of loose coiled loom, the ECU hanging dowm from its plug, battery right in the way, etc. Tiny garage does not help sane access to the passenger footwell either.

Starting to think I am going to have to admit defeat and pay someone knowledgable to sort it for me. May get the raditor changed at the same time, as it has had a small leak for a while and needs topping up with about 1/2 to 1" of coolant after each drive.

Not the best way for my TVR to enter 2007.....

[tvr_nut]

Paul V said:

If worst comes to worst and you can't find the second supply you could wire it up as mine has been, Take a live and earth connection from the back of the alternator, (make sure you fit a inline fuse within the first few inches), run in down the inner wing, connect this to a relay then take a feed off the working fan connection to switching the terminal of the relay, run the power output of the relay to the fan which wasn't working and you will have both working again. That is a last resort mind and best replace that seized fan first as well.

Paul,

The same thought had crossed my mind too. Only concern then is that if the #1 fuse (a 25A in my car) fails, both fans would then fail to start, and a boilover follow shortly after. The current system (when it worked) gave a degree of redundancy. As you say, keep as a last resort, I think - but thanks for the info on how to go about wiring it.


Neil

[Paul V]

As an alternative you could find out how the otter switch is wired and use that as the switching point rather than the other fan supply, that way you wouldn't lose both fans if one fuse blew but to be honest though in 4 years of ownership and trips to Italy etc I've never once had the 25 amp fuse blow but did have a problem when the extra relay stopped working and I tried going back to a single 40 amp fuse, it blew pretty quickly with both fans on it so I have gone back to the extra relay method and works well. Mine also is wired so if the air-con is switched on then one fan comes on automatically.