+2

 

Today was a beautiful day and my wife didn't have a list for me so I wired up the resister. Alas, it did not fix my low speed.

I know that the relay that is mounted on my fan is flaky and that my 2003 has the old style fan with the relay on the fan assembly rather than in the fuse block. That might be the difference.

But for me, when I do the lower control arm bushings in a couple of weeks, I'll be doing a fan too.

And it looked so good mounted on that aluminum support.

Rich

 

try a relay by the new resistor! Actually, you should be able to get it to fire on it's own with some creative temp wiring.

Anyway, if there's a relay on the radiator support, there would only be one high current feed, and something to control the relay (12 volt, low current).

Matt

 

What I am posting here is not news for most of you, but might provide some useful details unique to this production model. I wrote this up for the MiniUSA discussion board, and copy it here:

Well, I have had a few interesting hours investigating my auxiliary cooling fan. I have a copy of the Bentley service manual and have been investigating the wiring schematics. I have a 2005 S convertible, 6 speed automatic.

So, to review, the dealer says I need a new auxiliary cooling fan, total $670. The fan assembly is about $300 (dealer), and it is a ton of labor to replace, because basically you can't replace anything on the cooper without removing the bumper or the intercooler. This thread about replacing a resistor was too much of a tease to ignore. My investigation is limited because we are a two car family, I have limited time, and thus can not risk leaving the car disassembled and out of service.

So here is my review of the schematics and actual field test results. The fan is a simple, one winding, motor. It receives power either from a high speed circuit or from a low speed circuit through the famous resistor. Important point here: if the fan works at all, there is nothing wrong with the fan motor. The motor itself is not at fault for failure at low speed.

The digital motor control, from what I understand, requests low speed fan either when the air conditioning is operating or at the first elevation in coolant temperature. It requests full speed operation when the coolant temperature reaches an elevated temperature.

To request low speed operation, the computer activates a relay in fuse holder 3 that closes a path from 30 amp fuse F08 to the resistor and then to the fan motor. This same relay closes a path from the same fuse to a relay that activates the steering pump fan. Second important point here: if the steering pump fan is working, then the control mechanism for low speed auxiliary coolant is functioning. To request full speed operation, the digital motor control activates another relay in fuse holder 3 that closes a direct path from 50 amp fuse FL9 direct to the fan motor.

[deleted my observation that duplicates most recent fix described in this thread]

To confirm my assumptions I tested a number of circuits. I found the plug connecting the fan wiring to the body wiring next to the air intake on the driver side, mounted to a bracket that also supports what I believe is a refrigerant connection for the air conditioning. It is a good size plug about the size of a C battery with three pins and one unused pin opening. Somewhat related, the Bentley manual says there is a ground bus below the hood latch here too, but all I found was what appeared to be a ground connection. I did find a ground bus below the passenger side hood latch. Another note, the Bentley manual lists in this wiring harness a brown ground wire, a red/blue wire for the full speed circuit, and another red/blue wire for the low speed circuit. My car has a slightly smaller gauge red/green wire for the low speed circuit. The pin positions also do not match, either counting clockwise or counterclockwise. With some careful examination and a flashlight, I was able to detach the plug from its support bracket with a miniature flat blade screwdriver. There is plenty of slack in the fan wire so the whole junction can be pulled out for closer examination.

I disconnected the plug and tested across the fan pins for resistance. Ground to low speed pin was open, which would be consistent with the burned out resistor. Ground to high speed pin showed a closed circuit. I reconnected the plug

I started the car from cold and let it idle. Using a needle probe on my meter, set to voltage, I poked through the insulation on each wire on the fan side of the plug and found no power. Then I turned on the air conditioning, and found power on the low speed wire, but the fan was not running. I then turned off the A/C, and after a delay, the low speed wire power stopped. I waited while the engine idled, and continued to test each wire, but saw neither power nor fan operation. It took forever for the temperature gauge to rise. It is an unusually cool day today. The gauge never made it to the halfway mark. I took the car out for a few trips around the block, but still never heard the fan operate. So my diagnosis ends there.

****

Since there is plenty of slack on the fan side of the wiring, I plan to mount a resistor similar to other posts here and wire it into the fan side of the wiring. That way I am not modifying the wiring on the body side of the system.

Thanks for all the earlier posts with detailed analysis and solutions!

 

Quickbooks: excellent write-up. Where in Ohio are you?

 

Quickbooks, a very interesting read. Can you describe, for low IQ visually oriented people like me, what the point-to-point wiring will be that you are testing?

Is it inserting the resistor between the brown ground wire and the other red/blue wire for the low speed circuit?

 

On my 2004 MCS, the harnes has three wires - one brown and two reddish. I believe that the resistor will connect to the two reddish wires. I am about to confirm this and will report back.

 

For my own benefit (sorry, I know all you guys have been through this before):

May 2002 MCS, I have high speed but no low speed

Here's the connector


You can see the second connector for the PS fan above, and the numbers are from the connector itself, 1 is brown, 2 and 4 are red/blue

Here's ELE-97 from the Bentley manual:


In my case, the pins on the connector and the pin notations in the diagram do match. So, 1-Brown is ground, 2-red/blue is 2.5mm low speed and 4-red/blue is 4.0mm high speed

 

and here's the offending little bugger:


Since that resistor has failed in an open state, I need to insert a replacement, on the fan side, between pin 2 and pin 4:


IO1135 is a relay FROM March 2003, which I should not have in my '02 MCS, so it should be a simple matter of wiring a replacement resistor between the two red/blue wires before or after the connector.

I think ....

 

Gear-Head: if the diagrams you post accurately reflect your car, then the resistor between wires 2 and 4 will not work. Note the relay on the fan side only closes at full speed operation. [my diagrams are different]

I have the exact same plugs, but I did not see any numbers on the plug, hence my comment. I guess the pin locations are neither clockwise or counterclockwise, but zig zag.

 

My fan also has two plugs as does yours. And the relay on the fan rather than in the fusebox.

I checked the connections again today. Everything is connected correctly (bridged the browns) and and no low speed for me.

I am going to do lower control arm bushings in a few weeks. While I have the car apart, I might just slip in a new fan and call it a day.

Rich

 

Right load of bollocks this, innit?

Checking again, in the engine Fuse and relay panel:

In the Bentley manual "Electrical Component Locations" this is noted as Engine Cooling Fan relay (stage 1) (IO1152)

But in the same manual under Electrical Wiring Diagrams (ELE-9), part IO1152 is noted as Engine Cooling Fan relay (stage 2)

Based on everything I've read here, I'm inclined to believe it is the Stage 2 relay, and the stage 1 relay is mounted on the cooling fan behind the radiator. So bridging the wire with the resistor isn't going to work for me.

Bugger

 

Gear-Head: Your diagram matches your visual. Note "x53" on the diagram refers to the physical plug, and the relay is shown on the fan side of the plug in your diagram.

I pulled out my manual and see you are looking at the pre-2003 diagrams, ele-96/97. My car is the next page, ele-98/99, where you can see the relay location has changed.

You could still wire in a more robust resistor, but you would have to gain access to the fan to feed your low speed current to the other side of the relay. That may require the whole disassembly sequence. Probably still better than replacing the fan, since it appears from other comments that the new fan does not have a more robust resistor.

 

I will probably get a new fan, and wire in a new more robust resistor before installing it. I also want to install an analog temperature gauge, so I might as well do the whole thing at once.

Cheers.

 

So ... since I have to replace the fan assy, I got the proper pre-March 2003 version from Rockauto, $96.32 incl. shipping.

Here are the bits causing me trouble, looking nice and new:

What someone referred to earlier in a post is not a voltage divider, it appears to be a diode (to conduct current in only one direction)

So, option 1, I install this new fan assembly, as is, and hope for another 4 years out of it.

OR, solder two pigtails to the resistor, cap them off and leave them available to wire in a new resistor once this one fails:


OR, it looks like if I remove the green resistor, the Aircol might fit right in with a bit of creative wiring and removing a bit of plastic here and there


Not sure which way I'm going to go yet ...

 

If greeny is failing due to a hostile environment.

What if you sprayed the green bugger in the new assembly with PlastiDip?

Would that obviate the cause of greeny failing?

 

I argue that mounting the resistor in plastic is the problem. The new resistor will fail again because the plastic does not conduct heat away and it appears the fan does not circulate air across the resistor.

The position demonstrated in the photo will make it worse, because it blocks what little air flow is designed to pass over the existing resistor.

Mounting the resistor on the metal car body will make a large improvement, because the car body will conduct the heat away.

 

Ah. So it's not just a matter of protecting it from salt spray and such.

Perhaps pigtails with a nice connector on the other end which would match up to one on your new resistor?

 

I'm leaning that way. I'm not sure how well the solder will hold on there, but I'm going to try that tonight. If all goes well, I'll leave the greenie in until it fails, then when it does, I'll extend the pigtails out to the body and attach the aircol resistor there.

 

I agree. I saw a post somewhere that showed a failed green resistor. It was obvious it got too hot, for too long and when that happens the coil of wire heats up too much and poof!

 

DONT do this!
The Arcol needs a heat sink and you are also blocking the airflow duct!

 

No, I didn't. What I did do was solder a 12" pigtail to the green resistor, and wrap it up nicely. When the green bastard fails, I'll unwrap the pigtail, run it out to the body somewhere and install the aircol

 

thanks again for the reply back!

nelson

 

I am about ready to pull the trigger on one of those too. Did you compare it to the OEM fan? Does it look like the same parts at 1/3 the price?

And I LOVE the idea of the pig tales. I do wish the 61360141229 relay was still available. Otherwise I would simply get one of those, cut out the old resister, install the auxiliary resister and the new relay which sometimes sticks on Artoo.

Did I mention I love the idea of the pig tales?

Rich

 

Quality looks good, the fan unit itself feels good and solid. In my case (pre-March 2003) both connectors look identical to what's on the car now.

I decided to wait until the end of June when I visit Helix (yes finally!) and have them install the assembly for me along with the new pulley