456 Small Fan Switch

Hello. Did you find the sensor that activates this small fan?

Also which fan comes on with the ac turned on?

 

Stu- Not sure of exactly when the oil cooler fan comes on, but it is likely at a much higher temperature than the coolant radiator fans. Max allowable oil temperature is way higher than max allowable water temperature and normal operating range differences are even larger. The warning light temperature for water temperature is 257F, and it is 302F for oil temp in a 575M.

 

Which car do you have? 456M? 456GT? 2.7? 5.2?

Looking at the Ricambi America site, the GT car seems to have a sensor on the right hand water manifold (under the engine plenum) (as Stu says)

Item 33 (on the right hand side)

https://www.ricambiamerica.com/car-diagrams/ferrari/v12/gt-group-2-2/456gt/water-pump.html

However, it may vary depending on 2.7 or 5.2 cars. Note that Ricambi doesn't show a sensor on the right hand water manifold for the 456M. There is no hole for it.

You should be able to trigger the fan at the footwell relays with a jumper wire (Caution: power comes directly from the battery and the fans use high currents). You may be able to trigger the fan more safely by powering the relay solenoid if you can find the applicable relay panel connector. Unfortunately, I only have (useful) diagrams for the 550. I haven't been able to find the solenoid trigger wire on the 456. Relay "I" controls the oil radiator fan.

Do you have a specific problem?

 

The 456M workshop manual has these comments which may be applicable to 2.7 cars (if they don't have the water temp sensor on the right hand water manifold):

I assume, they mean the HVAC ECU.

Is the thermal contact the one under the radiator as previously shown? I assume the temperature control system "pressure gauge" is one of the pressure switches on the receiver-dryer. On the 550, one of the fans is triggered if the pressure reaches a certain value (A high pressure means that the aircon system has a significant load on it).

Staggered fan activation will reduce the load on the electrical system. Is the 456 workshop manual hinting that left and right fan operation is not independent (at least on the earlier cars)?

 

Hey
My one is a early 1994 456GT 2.7 motronic.
Recently I changed the waterpump, aux pump and flushed out the coolant to zerex G05. The less mix of coolant I have the lower the temp. However this time one fans not working properly. Really want to go brushless fans now.

 

Not working properly, Prit? Is it running slowly, intermittently, not at all? If not working at all...

Assuming 2.7 cars have a single water temperature sensor for fan control and the big fan is working, your HVAC system appears to getting a suitable temperature signal from the sensor and is responding to it. To have the smaller fan run 2 seconds later than the bigger one, you need separate wiring and relays for the 2 fans. If the electrical plug on the small fan is not easily accessible for checking voltage supply (with the other fan running), I would try interchanging relays in the footwell as a first step. Interchange a non-essential relay with the same part number. e.g. rear window heat (if the weather is warm).

 

Hey yes the both fans seem to be coming on. However I can hear one fan kick in at higher speeds for about a few seconds and then switch off not bringing the temperature down to 90c. Its staying over 110c at idle. I will change out the relays first. Many thanks
View attachment 3627409

 

Strange. It doesn't really sound like a relay problem, but interchanging the relays will, at least, take the relay out of the equation. Sounds more like a tired fan.

Check the fuse and holder to make sure it's not showing signs of heat stress. Fans often draw high currents when they are about to expire. It's important to find the source of the problem before you start having relay panel internal wiring problems.

 

If your relay panel is the same as earlier cars...



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That fuse doesn't look particularly healthy. What's happened to the amperage rating lettering?

Is your original photo upside down or is the panel different on some cars?

 

I think the picture is upside down--note the lettering on relays.

 

The lettering on my F355 relay panel is the right way up but the relay lettering is upside down. I have a right hand drive car. On left hand drive cars, the opposite is true. Prit is from London, so he may have a right hand drive car. I wasn't sure if the relay panels were reversed on RHD 456's.

 

Hey

Yes Im from UK London. However my car is a left hand drive. Love at first site when I went to view the 456 and have to had it.

The fuses will be replaced and the relays updated. Looks like the have been changes out recently. Anyone have a good source for a full electrical diagram for these cars?
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That's a bad sign. I would look into buying a new fan as soon as possible.

Thanks for the new pics. I didn't realise the panel was mounted vertically. The WSM shows it as being horizontal.

Unfortunately, there are no traditional wiring diagrams available to us for the 456, only plug pinout diagrams. In some cases, however the wiring is similar to the 550's.

Here is a simple diagram I put together for you (from the relay to the plug). It shows the panel in a horizontal position, but you should be able to figure out which is plug "1D" (it's the one next to the battery connector "6D" (with the really thick cables)

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I was going to get you to check the earth for the fan, but it looks like it's behind the front bumper (not easy to get to). I guess it should be ok, however, as your suspension system and right radiator fan would probably be playing up if there was a bad earth.

Note that Ferrari have a bad habit of showing relay connections incorrectly in their diagrams. The output of the relay to the fan may or may not be on relay pin 87.

By the way, Prit, would you be able to update your profile to show the car you have (in case we forget).

 

The 456 Workshop Manual is a complete mess. Here's a diagram for the front harness (in the engine bay)

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In one part of the manual, it identifies plug 12A as being the fan for the left hand radiator and 9A as the plug for the right hand radiator. In the diagram above, it appears the opposite is the case. I can no longer guarantee that the diagram I uploaded in the previous post is correct.

The only way to confirm which is which is by looking at the wire colours. One is black-blue, one is blue-green (I'm referring to the power wires).

 

That's fascinating. Well done.

As for the relay, 87 is more than likely the output (standard bosch relay pinout is always 30 in, 87 out ) when it is energised. 87a if it is open

 

Yes, more than likely. However, a fellow FChatter is currently running wiring checks on his 550 fuse panel. He's found a number of oddities (including swapped 30&87 functions) which I will try to incorporate into my revised/coloured 550 diagrams. Same for fuses (not all the fuses have incoming power on the same side). I'm also aware of similar oddities on the F348. You really have to be careful when testing Ferrari circuits. Some contacts can be live when you think they shouldn't be.

 

You might be right (for the "GT" car). The WSM for the "M" car has a basic wiring diagram showing how the HVAC controls both fan relays (so does the HVAC on the 550, but the right coolant temperature sensor is a backup for both fans if the HVAC fails to keep the temperature under control). For the "M" car refer to WSM page "I-12"

Looking at the parts catalogue for the GT car, it looks like it has two coolant temp sensors whether it has a 2.7 or 5.2 Motronic system (but not necessarily the same part number as you have shown in your quote in post #2. As your quote (in post #2) also shows, the right temperature sensor controls the left fan (via the Right Motronics ECU). The Right Motronics ECU may have direct control over the right fan relay on the GT car.

(EDIT: Was that excerpt from the manual in post #2 relating specifically to GT cars? If not, the right coolant temperature sensor may send a signal to the Right Motronics ECU and the Motronics ECU may tell the HVAC ECU to turn on the left fan?)

 

Interesting. Seems I have another manual. All the chapter titles show "M", but the GT is mentioned from time to time. Oddly, my manual mentions the 5.2 only. The wiring diagrams seem incomplete. Is L77 the last page?

My "B-80" page is completely different from yours.

 

The students who put the manual together for Ferrari missed a decimal point or two. Plus or minus 3.5 degrees F makes a lot more sense even if it should be 3.6.

 

Here's the diagram from my manual (456M?)

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If the HVAC ECU generates an earth at pin "X", the right fan comes on. If the HVAC ECU generates an earth at pin Y and X, both fans come on. Receiver-dryer switches can also turn on both fans. Having said that, these type diagrams are often wrong (or simplified)