Z3 2.8 electric fan failure

[Dakar Ole]

[QUOTE=deni2s;28742373]Tried to remove my temp switch for testing in boiling water, but then the coolant is leaking out and I don't have a spare coolant, so no actual testing now.

Put a cork in it. lol Seriously!

[CarPrep]

Thanks for this thread. I did a fan delete a couple of years ago and haven't really had any problems except when I'm pushing it a bit going up hill. I thought maybe it was due to low coolant or air in the system but that's not the problem. I just checked the wiring on my car (build date 5/1997) and the brown wire is on the side and the green/black is in the middle. Should I just swap these two wires? If so, how do I do this?

[jajou318]

Thanks for this thread. I did a fan delete a couple of years ago and haven't really had any problems except when I'm pushing it a bit going up hill. I thought maybe it was due to low coolant or air in the system but that's not the problem. I just checked the wiring on my car (build date 5/1997) and the brown wire is on the side and the green/black is in the middle. Should I just swap these two wires? If so, how do I do this?

Unplug the harness and you can probably take it apart and pull the wires you need to switch out then reassemble

[328 Power 04]

Ahh, Spartansburg wreaking havok all over the world.

[deni2s]

Having just dealt with this, the radiator temp switch plug test should be pin 2 shorted to pin 1 for low speed fan, and pin 2 shorted to pin 3 for high speed fan. Pin 2 wire color should be brown.

Marty

Ok I've changed my wiring to work as described by Marty above and I now have an aux fan that comes on (without ac) at the low speed when the car is idling for a long time!
(I also have the viscous fan in place so this is working in addition).
Can't say I've ever heard the aux fan come on without the AC until today.

When I put the ac on the aux fan now comes on at low speed (before I'm pretty certain it was going at fast speed only).

According to 99 year model manual diagram, which we agreed to be correct, and conclusion in http://www.bimmerforums.com/forum/sh...-fan-confusion shortening pin 2 (brown) and pin 3 (green/black) should be low speed - not like MartyBtoo says...



So all three wires need to be switched, not only two.

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Tried to remove my temp switch for testing in boiling water, but then the coolant is leaking out and I don't have a spare coolant, so no actual testing now.

Put a cork in it. lol Seriously!

I will try that when I will have free time. Too much confusion otherwise.

[Dino D]

I simply checked which wires do what in my car as clearly the theory vs practical is different.
I would suggest that anyone else doing this check which wire actually does what on their car too before changing anything.

This is how it's wired now on my car
1 - green/black (previously brown)
2 - brown (previously green/black)
3 - black/grey (as it was already).

Short 2-1 = slow
Short 2-3 = fast

EDIT: AFTER THE POSTS BELOW AND TESTING AGAIN THE ABOVE WIRING CAUSES THE HIGH SPEED FAN TO COME ON (RATHER THAN LOW SPEED)

[deni2s]

I simply checked which wires do what in my car as clearly the theory vs practical is different.
I would suggest that anyone else doing this check which wire actually does what on their car too before changing anything.

This is how it's wired now on my car
1 - green/black (previously brown)
2 - brown (previously green/black)
3 - black/grey (as it was already).

Short 1-2 = slow
Short 1-3 = fast

I think you meant Short 2-3 = fast. Still something wrong... What exactly and how did you checked? Should be:
Short 1-2 = high
Short 2-3 = low.

Unless you checked what does temp switch at which temp and you can confirm, that it shortens 1-2 after 91C and 2-3 after 99C, which would be the opposite to even the latest manual.

[CarPrep]

Dennis, Denni, Dennis. I am indeed correct, and Marty is very close. Scroll down the diagrams to figure 8500.0-05 Figure #4. The Brown wire is on pin 1. Pin 1 is in the MIDDLE. Like this.

.....1.....
3.........2


Your plug is wired incorrectly if the brown is on the edge.

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Since the forum software keeps stomping on the formatting, screen grab:

Attachment 545222

Randy-
With the brown wire in the middle (#1) which wires should be on #2 and #3 or does is matter? When I looked at my plug I had Green/black in #1, Brown in #2 and Gray/black in #3. So I just switched #1 and #2. Is that correct?

[Dino D]

I think you meant Short 2-3 = fast. Still something wrong... What exactly and how did you checked?

Yes that what I meant, just corrected my post above!

I have to say the diagrams and various combos are confusing (!). So how I checked is simply by shorting the pins to see which wire activates low and which activates high speed.
I ignored colours of the wires as that could be mixed up from factory.
On the assumption that the switch itself is wired correct I then did as per Marty did his.

Then ran the car to see if the low speed fan kicks in at idle which it now does (never did before).
I have a new 80/88c fan temp switch from the M44.

[deni2s]

Yes that what I meant, just corrected my post above!

I have to say the diagrams and various combos are confusing (!). So how I checked is simply by shorting the pins to see which wire activates low and which activates high speed.
I ignored colours of the wires as that could be mixed up from factory.
On the assumption that the switch itself is wired correct I then did as per Marty did his.

Then ran the car to see if the low speed fan kicks in at idle which it now does (never did before).
I have a new 80/88c fan temp switch from the M44.

I believe your fan with your new wiring kicks at high speed and not low speed as it should.

[rf900rkw]

There are two different plugs. Supposedly the change over was '98, but I'm suspecting it was really a bit before that. The operation of the switch did not change. But the pin numbering did. In other words, they changed the house numbers. This is complicated by them not changing the wiring diagram to match the new numbering scheme until the 99 issue.

The diagram I drew above, a long ways back, is for the early large connector. The new smaller connector has the numbers cast in right next to the wires. Per Deniss' (sorry about the American spelling earlier) latest diagram, the wres should be

1 - Black/Grey high speed
2 - Brown common ground
3 - Black/Green low speed


The way the switch works is 2 and 3 are connected at 91C. At 99C, pin 1 is added to the gang. The 2-3 bridge is not dropped, pin 1 is just added. Thus you have all three ganged together.

They way the factory miswired the plug, at 91C the low and high speed lines are connected. Nothing happens. At 99C, the ground is added, pulling both sides in at once. By Dino's picture, all three wires are incorrect. If you just switch the brown and black/green, you will have high speed at 91C, and low would be added at 99C, which would do nothing since the high is already on.

[deni2s]

There are two different plugs. Supposedly the change over was '98, but I'm suspecting it was really a bit before that. The operation of the switch did not change. But the pin numbering did. In other words, they changed the house numbers. This is complicated by them not changing the wiring diagram to match the new numbering scheme until the 99 issue.

The diagram I drew above, a long ways back, is for the early large connector. The new smaller connector has the numbers cast in right next to the wires. Per Deniss' (sorry about the American spelling earlier) latest diagram, the wres should be

1 - Black/Grey high speed
2 - Brown common ground
3 - Black/Green low speed


The way the switch works is 2 and 3 are connected at 91C. At 99C, pin 1 is added to the gang. The 2-3 bridge is not dropped, pin 1 is just added. Thus you have all three ganged together.

They way the factory miswired the plug, at 91C the low and high speed lines are connected. Nothing happens. At 99C, the ground is added, pulling both sides in at once. By Dino's picture, all three wires are incorrect. If you just switch the brown and black/green, you will have high speed at 91C, and low would be added at 99C, which would do nothing since the high is already on.

I just did the testing of my temp switch by putting it in boiled water and checking with tester and I can confirm what Randy says. So looks like Dino D and Marty don't have 100% correct wiring.

[Dino D]

Ok, I've checked again and listened more carefully to the speeds when shorting the wires and rewired as per above so it is now:
1 - black/grey (was brown)
2 - brown (was black/green)
3 - black/green (was grey black)

The low speed fan now comes on as it should. As I had it wired yesterday the high speed was coming on rather than the low speed.

Thanks all!

[MartyBtoo]

First, apologies on my assumption of pin numbers; nothing was marked to indicate that pin one was the center pin, so I made a bad assumption. My wiring has always had brown in the middle, now known as pin one.

Well, I made another change, and I'm still confused. In my original setup, the fan came on low with the AC, and by shorting pin one to the other pins one at a time I could get low and high speed fan. With mechanical fan removed and the car idling, temp would get up to the 75% dot on the gauge, the fan would come on at high speed, but then shut off completely when the gauge was down to maybe 65%.

Today I tried changing the radiator fan switch itself, then tried the experiment again. This time the fan stayed off until the gauge reached the 75% dot, then the fan came on at high speed, but this time when the gauge got down to the 65% point the fan switched to low speed mode and stayed running until the gauge got back to the centered normal point, and then it shut off. I'm still a little mystified on why the fan didn't start on low speed first when it started to heat up, but it ran in low speed mode after it had started in high speed. I'm going to drive around a bit this afternoon to see if I trust it to work okay for the round trip to Dorkfest, or if I'll feel like putting the mechanical fan back on again.

Marty

[deni2s]

First, apologies on my assumption of pin numbers; nothing was marked to indicate that pin one was the center pin, so I made a bad assumption. My wiring has always had brown in the middle, now known as pin one.

Don't call it pin one, you are just making confusion for others, because on latest diagrams pin #1 is something else. Call it ground wire.

And remember that gauge measures temp somewhere else, not where the temp switch is, so the temp on the gauge and near the temp switch can be different. And the most important thing - you have your other wires wrong. Switch them around. Most probably this is what was happening:

1) temp inside engine (at the gauge) got to 75%, coolant inside the engine tries to cool it down.
2) hot coolant from the engine (between 91C and 99C) gets to the radiator and tries to enable low speed on fan. Because you have your other wires wrong, it enables high speed instead of low speed.
3) while cool coolant from radiator goes to the engine, more hot coolant from the engine goes to the radiator and it gets over 99C here. Tries to enable high speed fan. The thing with high speed on temp switch is that it actually has some resistance inside the switch (for low speed there is no resistance). Because you have your wires wrong, this resistance might be enough to turn off high speed fan and leave only low speed.
4) coolant cools the engine completely and at this point also the switch turns off everything.

Show us your wiring. I am pretty sure you need to switch black/gray and black/green wires.

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CONCLUSION

Correct wiring diagram:
elettroventolaadueveloc.jpg

Connector to temp switch (X87) wiring diagram (pin 2 is in the middle):
Screen Shot 2015-08-19 at 00.51.16.png


Correct wiring to pins:
1 - Black/Grey high speed
2 - Brown common ground
3 - Black/Green low speed

Temp switch bridges pins 2 and 3 at temp over 91C.
When temp goes over 99C it bridges ADDITIONALLY pin 1 with pin 2 with some resistance. So all three pins are connected.
For testing purposes just bridge pins 1 and 2 for high speed and pins 2 and 3 for low speed with ignition in position 2. Just turning on condition while car is not driving should turn on fan on low speed (if it is not already running on high speed).

Temp on the gauge is NOT measured near the temp switch inside radiator so it is not the guide for temp switch operation.

Coolant must be over min level, otherwise temp switch in upper part of the radiator will not work as it should.

[MartyBtoo]

Okay, tomorrow I'll doublecheck the exact wiring of the two fan wires at the plug. The comment about the coolant level caught my attention, as I did lose a little coolant when I swapped the switches; it was about 1/4 inch below minimum. I was actually driving into town to get some distilled water to bring it up to minimum while checking it out.

I do realize that the water temp sensor is not the same as the fan switch temp, it's just the only reference I have!

Marty

[MartyBtoo]

Okay, I checked the wiring on the plug, and it is exactly as specified. I did check the coolant level again without starting the engine, and it is back down to the minimum, so my working hypothesis is that I'm still working an air bubble out of the top of the radiator. I filled it to the max point, will take it for a drive to see what happens, then will check it cold tomorrow and see what happened. Fingers crossed!

Marty

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Well, I give up for now. I took a drive on my test loop, and everything seemed fine until the very end, when the heat soak plus low speed driving sent the temps up again. I got it home, let it idle a while, and at the 75% point the electric fan kicked off in high, then when it cooled down to maybe 65% it shut off again. For the run to Dorkfest I'm going to reinstall the mechanical fan, and take a shot at it later.

I've changed the coolant switch, the low speed relay, it comes on low with the AC, the wiring is correct, the fuses are good, and shorting the plug socket yields both low and high speed as appropriate. I've run out if ideas for now.

Marty, disgusted

[Dino D]

Can't help further but can add that using the dash test functions to get the actual temps (not buffered as per the gauge) is very useful to keep an eye on temps.

[deni2s]

Can't help further but can add that using the dash test functions to get the actual temps (not buffered as per the gauge) is very useful to keep an eye on temps.

More info about that here: http://www.zroadster.net/forum/viewt...hp?f=5&t=37703

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Well, I give up for now.

Please post the pic with your wiring. Just double checking.

[rf900rkw]

Marty, it sounds like you have an air pocket still. The level in the bottle does not matter *until* all of the air is out of the head and radiator. Yes, when the system is properly bled, the water level in the radiator is much higher than that in the bottle on the front mounted M/S52 systems.

[MartyBtoo]

More info about that here: http://www.zroadster.net/forum/viewt...hp?f=5&t=37703

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Please post the pic with your wiring. Just double checking.

IMG_0213.JPG

Sure looks like pin 3 has got a green tracer to me!

Marty

PS I jacked the front end of the car up about 2 feet, then ran the car at 2500 RPM for about a minute; shouldn't that have gotten rid of any air bubble? I'm getting a solid stream of coolant coming from the radiator vent tube into the expansion tank.

[deni2s]

IMG_0213.JPG
Sure looks like pin 3 has got a green tracer to me!

Connector looks different than the one I had.

[BimmerBreaker]

Marty if you are diagnosing an S54 I wouldn't count on it being the same as the M52 being discussed here

[deni2s]

Marty if you are diagnosing an S54 I wouldn't count on it being the same as the M52 being discussed here

2000 M roadster has the same connector wiring as 2000 Z3.

[rf900rkw]

The fan switch is the same. The rest of the cooling system is different.