General bloody bravo!
- Thread starter sp33d12
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General bloody bravo!
here we go!!!
i've studied the fan wiring diagram and i can confirm its a bloody complicated setup (my favourite)
when I use numbers in brackets they are the numbers from the list in my previous post. The car image allows you to locate any component, the wiring diagram shows how they are connected.
there are 2 fans. (154 on diag is normal fan, 237 on diag is additional fan, both at top center of diag)
each fan is constantly live. each fan has its own live supply. each live has its own 40a fuse before the fan. the connector you have shown in your pics that says "both live" is the connector that connects the fused lives to the fans (128). Your test proves both fans are getting a live supply
each fan has a wire that then comes from it, these will also be permanently live (unless a fan has an internal fault), and both go to a 3 pin connector (126). For the low speed fan this wire first goes through a cooling fan limiting resistor (170) which is what limits the fan’s speed (by increasing resistance in the circuit) and then on to the connector (126). For the high speed fan the wire splits into 2 and then goes on to the connector.
We need to do a test at this point to ensure what we expect is actually happening, and to rule out internal fan faults or a faulty cooling fan limiting resistor (170)
test
use above info to locate connector 126 on your car.
on connector 126 there are 3 wires, these are the 3 wires discussed above (1 for low speed, 2 for high speed)
disconnect the connector and test using the pins on the fan side of the connector (the live side)
all 3 wires on that connector should be live. Test the pins to make sure.
now try earthing each of the pins using a length of wire to the chassis.
When you earth one it should switch one fan on. Check that both fans work in this way. 2 wires will be for the high speed fan and both should switch it on, the other wire is for the low speed fan and it should switch it on noticeably slower than the other fan.
Considerations in test1:
If only 2 of the 3 pins show a live there must be a problem. This can be due to an internal fault in a fan (no current passing through 154 or 237), a broken cooling fan limiting resistor (170), or a broken ultrasound soldered joint taped in the loom (N.D.)
If there is a live at all 3 pins but only 1 fan works we know that one fan is faulty but still passing current through. This means you need to replace the fan.
The results of this test will dictate what we try next.
now the interesting bit.
the fans are switched on and off by what happens after the 3 pin connector we just used in the test (126), this means they are negatively switched. this is done by the relays.
the low speed fan’s wire goes from the cooling fan limiting resistor (170), through the connector to the low speed fan relay (122).
the high speed fan’s wires join back into a single wire after the connector and this goes to the high speed fan relay (123a).
the wires join their relays at pin 30 on each relay.
So, how do the relays switch on the fans? what triggers them? how can we test them?
well a quick look at the wiring diagram tells me:
1. each relay has 4 wires connected to it
2. each relay has 1 wire from its fan to pin 30 (already discussed).
3. each relay has 1 wire going to the 2 stage thermostat (172) AND the cooling fan high speed timer (123), this is pin 85 on each relay
4. each relay has 1 wire that joins to a shared earth for both relays (pin 87 on each relay)
5. each relay has 1 wire (from pin 86) that connect to each other and also to several components. Including:
-engine cooling fan high speed timer (123)
-a/c compressor relay (124) [x2 wires, 1 for switch, one switched]
-a/c fan relay (205)
-fuse/relay unit [fusebox] (4)
the way each relay works is thankfully very simple. Pin 30 is connected to pin 87 inside a relay to switch a fan on. This switching occurs when the components that are connected to pin85 and pin86 on a relay open or close the switch by sending a signal through the relay on these pins.
So, assuming in the test above we found that both fans work (switched on when earthed), we then need to think what could be preventing either fan relay from switching its fan on.
Without looking at the next stage of the circuit (yes it gets worse), we should first examine the list of possible causes we have already identified and look into ruling out each possibility.
The list so far is:
-2 stage thermostat (172)
-cooling fan high speed timer (123),
-engine cooling fan high speed timer (123)
-a/c compressor relay (124)
-a/c fan relay (205)
-fuse/relay unit [fusebox] (4)
So if we remember what your symptoms are, and think a little bit about what each of the components on our list does, we can identify a likely culprit or two.
The 2 stage thermostat (172) contains 2 switches which open or close based on temperature.
The first switch closes at a lower temperature and this is used for the low speed fan. When the switch closes, pin 85 on the low speed fan relay (122) is earthed. This will then close the switch in the relay and turn the low speed fan on.
The second switch closes at a higher temperature and this is used for the high speed fan. When the switch closes, pin 85 on the high speed fan relay (123a) is earthed. This will then close the switch in the relay and turn the high speed fan on.
This tells me that both fans should be on at a high temperature (unlike my assumptions in previous posts).
This also tells me that the components connected to pin 86 on both fan relays should be sending a signal, and this signal is earthed by the 2 stage thermostat (172) to switch a fan on. If the components connected to pin 86 did not send a signal then the switching circuit in each fan relay would not be able to turn the fan on.
Obviously this means all the ‘things’ that can turn on the fans do it by sending a signal to pin 86 on each relay. Pin 86 on each relay are connected together, in fact everything connected to pin 86 on both relays are all connected together.
test
So now another test is in order. We can quickly rule out the possibility that the 2 stage thermostat (172) is faulty.
We base our test on the assumption already made. If we earth either wire going from a fan relay to the 2 stage thermostat (172) it should switch a fan on. If it does not we can assume there is something connected to pin 86 on both fans that is not sending a signal to the fan relays.
So how do we do this test? Thankfully we have connector 236 which is purely for the 3 wires going to the 2 stage thermostat (172). These 3 wires will be the shared earth and both the wires coming from the fan relays. Locate connector 236 using the info in my previous post (its in front of battery tray on pic, I think it may be the 3 pin connector in your pics). Disconnect the connector and use the fan relay side to do the test. The fan relay side will have 2 lives and an earth. Now you have the connector in your hand and you can see the 3 pins. Use a bit of wire to connect one of the lives to the earth. This should switch one fan on. Now do it again using the other live, and the other fan should switch on. You may need the ignition switched on, or even the engine, for this to work.
Assuming both fans switch on, we can also assume that both fan relays are getting a signal from the components connected to them. Then we can safely say the 2 stage thermostat (172) is faulty and should be replaced.
If 1 or both fans do not work in this test, we can assume life is going to be difficult and I will need to go to the next level of the diagram. My brain is already hurting so lets do the test first and then we can decide if I should make this essay any longer
if anything is unclear just ask and i'll rephrase it as best i can.
i've studied the fan wiring diagram and i can confirm its a bloody complicated setup (my favourite)
when I use numbers in brackets they are the numbers from the list in my previous post. The car image allows you to locate any component, the wiring diagram shows how they are connected.
there are 2 fans. (154 on diag is normal fan, 237 on diag is additional fan, both at top center of diag)
each fan is constantly live. each fan has its own live supply. each live has its own 40a fuse before the fan. the connector you have shown in your pics that says "both live" is the connector that connects the fused lives to the fans (128). Your test proves both fans are getting a live supply
each fan has a wire that then comes from it, these will also be permanently live (unless a fan has an internal fault), and both go to a 3 pin connector (126). For the low speed fan this wire first goes through a cooling fan limiting resistor (170) which is what limits the fan’s speed (by increasing resistance in the circuit) and then on to the connector (126). For the high speed fan the wire splits into 2 and then goes on to the connector.
We need to do a test at this point to ensure what we expect is actually happening, and to rule out internal fan faults or a faulty cooling fan limiting resistor (170)
test
use above info to locate connector 126 on your car.
on connector 126 there are 3 wires, these are the 3 wires discussed above (1 for low speed, 2 for high speed)
disconnect the connector and test using the pins on the fan side of the connector (the live side)
all 3 wires on that connector should be live. Test the pins to make sure.
now try earthing each of the pins using a length of wire to the chassis.
When you earth one it should switch one fan on. Check that both fans work in this way. 2 wires will be for the high speed fan and both should switch it on, the other wire is for the low speed fan and it should switch it on noticeably slower than the other fan.
Considerations in test1:
If only 2 of the 3 pins show a live there must be a problem. This can be due to an internal fault in a fan (no current passing through 154 or 237), a broken cooling fan limiting resistor (170), or a broken ultrasound soldered joint taped in the loom (N.D.)
If there is a live at all 3 pins but only 1 fan works we know that one fan is faulty but still passing current through. This means you need to replace the fan.
The results of this test will dictate what we try next.
now the interesting bit.
the fans are switched on and off by what happens after the 3 pin connector we just used in the test (126), this means they are negatively switched. this is done by the relays.
the low speed fan’s wire goes from the cooling fan limiting resistor (170), through the connector to the low speed fan relay (122).
the high speed fan’s wires join back into a single wire after the connector and this goes to the high speed fan relay (123a).
the wires join their relays at pin 30 on each relay.
So, how do the relays switch on the fans? what triggers them? how can we test them?
well a quick look at the wiring diagram tells me:
1. each relay has 4 wires connected to it
2. each relay has 1 wire from its fan to pin 30 (already discussed).
3. each relay has 1 wire going to the 2 stage thermostat (172) AND the cooling fan high speed timer (123), this is pin 85 on each relay
4. each relay has 1 wire that joins to a shared earth for both relays (pin 87 on each relay)
5. each relay has 1 wire (from pin 86) that connect to each other and also to several components. Including:
-engine cooling fan high speed timer (123)
-a/c compressor relay (124) [x2 wires, 1 for switch, one switched]
-a/c fan relay (205)
-fuse/relay unit [fusebox] (4)
the way each relay works is thankfully very simple. Pin 30 is connected to pin 87 inside a relay to switch a fan on. This switching occurs when the components that are connected to pin85 and pin86 on a relay open or close the switch by sending a signal through the relay on these pins.
So, assuming in the test above we found that both fans work (switched on when earthed), we then need to think what could be preventing either fan relay from switching its fan on.
Without looking at the next stage of the circuit (yes it gets worse), we should first examine the list of possible causes we have already identified and look into ruling out each possibility.
The list so far is:
-2 stage thermostat (172)
-cooling fan high speed timer (123),
-engine cooling fan high speed timer (123)
-a/c compressor relay (124)
-a/c fan relay (205)
-fuse/relay unit [fusebox] (4)
So if we remember what your symptoms are, and think a little bit about what each of the components on our list does, we can identify a likely culprit or two.
The 2 stage thermostat (172) contains 2 switches which open or close based on temperature.
The first switch closes at a lower temperature and this is used for the low speed fan. When the switch closes, pin 85 on the low speed fan relay (122) is earthed. This will then close the switch in the relay and turn the low speed fan on.
The second switch closes at a higher temperature and this is used for the high speed fan. When the switch closes, pin 85 on the high speed fan relay (123a) is earthed. This will then close the switch in the relay and turn the high speed fan on.
This tells me that both fans should be on at a high temperature (unlike my assumptions in previous posts).
This also tells me that the components connected to pin 86 on both fan relays should be sending a signal, and this signal is earthed by the 2 stage thermostat (172) to switch a fan on. If the components connected to pin 86 did not send a signal then the switching circuit in each fan relay would not be able to turn the fan on.
Obviously this means all the ‘things’ that can turn on the fans do it by sending a signal to pin 86 on each relay. Pin 86 on each relay are connected together, in fact everything connected to pin 86 on both relays are all connected together.
test
So now another test is in order. We can quickly rule out the possibility that the 2 stage thermostat (172) is faulty.
We base our test on the assumption already made. If we earth either wire going from a fan relay to the 2 stage thermostat (172) it should switch a fan on. If it does not we can assume there is something connected to pin 86 on both fans that is not sending a signal to the fan relays.
So how do we do this test? Thankfully we have connector 236 which is purely for the 3 wires going to the 2 stage thermostat (172). These 3 wires will be the shared earth and both the wires coming from the fan relays. Locate connector 236 using the info in my previous post (its in front of battery tray on pic, I think it may be the 3 pin connector in your pics). Disconnect the connector and use the fan relay side to do the test. The fan relay side will have 2 lives and an earth. Now you have the connector in your hand and you can see the 3 pins. Use a bit of wire to connect one of the lives to the earth. This should switch one fan on. Now do it again using the other live, and the other fan should switch on. You may need the ignition switched on, or even the engine, for this to work.
Assuming both fans switch on, we can also assume that both fan relays are getting a signal from the components connected to them. Then we can safely say the 2 stage thermostat (172) is faulty and should be replaced.
If 1 or both fans do not work in this test, we can assume life is going to be difficult and I will need to go to the next level of the diagram. My brain is already hurting so lets do the test first and then we can decide if I should make this essay any longer
if anything is unclear just ask and i'll rephrase it as best i can.
Last edited:
Ozric-Al
Established member
and all sing.......
"the resistor bone's connected to the, fan bone,......"
My head hurts after reading that (hate to think what yours is like after writing it Jug) but that looks like it should help you find the prob Davey-Boy.
Nice one Jug.
"the resistor bone's connected to the, fan bone,......"
My head hurts after reading that (hate to think what yours is like after writing it Jug) but that looks like it should help you find the prob Davey-Boy.
Nice one Jug.
Ozric-Al
Established member
oo-er!
if you want to keep it simple just ignore all the theory and skip stright to doing the tests on the 2 connectors, then let me know what happened and we can take it from there.
lol u saucy git... id feed you .. and get me woman to cook for you lol
im gonna have another read when i get home hope it seems a bit clearer for me
seems like alot of fiddling but it has to be done as its only gonna get worse when summers here.
.. and get me woman to cook for you lol im gonna have another read when i get home hope it seems a bit clearer for me
seems like alot of fiddling but it has to be done as its only gonna get worse when summers here.
Ozric-Al
Established member
lol u saucy git... id feed you
im gonna have another read when i get home hope it seems a bit clearer for me
seems like alot of fiddling but it has to be done as its only gonna get worse when summers here.
Well I've heard ya mum makes a mean sausage sandwich so I might be tempted next weekend but I think you really need this sorted sooner. Besides, Skater-Boy is still coming to mine tomorrow and then it's ma's day and grand prix sunday.
