About two weeks ago, I was out for a drive. Temperature was about 105 degrees, which is not unusual for this time of year in Las Vegas.
Suddenly, my temperature gauge started steadily heading up from center which is very unusual since it’s been rock steady since I’ve had the car.
Fortunately, I was about a mile from the dealership, and the red light and shut down the engine warning came on just as I pulled into the service area.

Dealer diagnosed a defective cooling fan assembly, but stated that the part is on back order. Given the forecast for record temperatures (~120 degrees), and the fact that the dealer has no indoor storage, I had my Vanquish sent home via flat bed to my air conditioned garage to protect it from the sun/heat. It’s been two weeks with no ETA from the factory on the part. I’ve checked multiple suppliers with the same response that it’s back ordered from the supplier.

I’m not sure how AM cannot keep this part in stock or on a short delivery time from the vendor since it is used across its entire V12 product line. I’ve owned two other DB9’s and never had this issue with parts availability.

Has anyone else experienced this?

Thanks,

Jim

 

I think Aston Martin Bits has one. Says compatible with all years Vanquish. Assuming your dealer will install it or your local indie shop will.

https://www.astonmartinbits.com/mode...2-4/parts/1700

 

Too bad something like this can sideline the car. It's unfortunate this is being sold/replaced as an assembly as it contains parts that are common that wouldn't be unique to AM.
This assembly contains:
2 fans with motors
1 control module
a harness
a frame to hold the parts which might be the only part that AM could have designed and had built. All the other parts are purchased from catalogs and likely common with other cars. That's the way a boutique car builder does it. Actually, the way many car builders do it.

If I had access to it I am confident I could get it back running. I would bet the fan motors (fans) are perfectly fine. 99% of the time the controller goes bad, usually burns a transistor. The control unit uses a PWM signal directly from the ECU. The PWM is a ground, the fans stay wired to +voltage and the pulse makes ground at varying frequencies to satisfy fan speeds the ECU wants. I've had a few encounters with these on other cars and almost always the controller went bad. In a couple of cases it was actually the relay burned as these are very high amperage. Assume the first check the dealer made was the relay.

If I had access to it I could check the fans in a matter of minutes, then I'd work directly on the controller. If I had it I bet I can source it.

 

Thanks all for your comments and suggestions.
I’m going to do a bit of troubleshooting while waiting to confirm the info above.

 

There is a cross reference parts list floating around the internet. I have some of it but can’t seem to copy to this page. Sorry. Not 100% sure but isn’t the fan set up from a Jaguar or parts of the fan assembly?

 

Thanks again to everyone.
Lead time from fan assy. manufacturer to Aston Martin is mid-September.
Did some troubleshooting to confirm what the dealer is telling me that it's a bad fan.
Car starts, comes up to temperature and is stable. Small fan runs, but the larger fan never starts, even with the AC system on max and driving the car at temperature. I'm assuming (maybe wrongly) that both fans should run together and vary the speeds depending on engine temperature.
80a cooling fans fuse is nice and tight in the fuse box.
I cannot get to the large fan connector to test it from above, but will get the car up on the Quick Jacks when I return from vacation in a few weeks to disconnect the fan, test it and work my way back to the fan control unit if needed.

Thanks again.

Jim

 

Finally got the car up in the air to test the large radiator fan.
First time with the Vanquish with QuickJacks. I needed to single point jack and place a 2x6 under each wheel to get the clearance needed for the carbon skirts.
Plastic under tray is a dream to handle compared to the metal one on my DB9.
Once the tray was removed, the fan module and fans were right there. I unplugged the large fan and connected 12v to it and it ran for quite a while with no problems.
I removed the fan control module and searched on the part number. It seems to be a Volvo part, but Volvo as with Aston Martin only sells the complete fan assembly. I found several new modules on EBay and ordered one for about $50.

JC

 

Amazing, JC. Thanks for posting an update.

 

Thank you for the detailed writeup for future reference/search

 

Excellent....thanks for posting.

 

Nice work.

In the several instances I've had with these modern fan assemblies where ECU is controlling fan speeds via a PWM ground signal, the module was almost always the culprit. Once you get the new (Ebay) part, if you can remove the cover on the control unit, I would bet money a burned transistor.

In the second pic in post #7, on the input side of the controller, there are two large wires coming in (+vs to each fan) then the much smaller yellow wire is the PWM coming from the ECU. In a couple cases I found a wire failure (not delivering the ground pulses from the ECU). That would not be your case as one of the fans is running normally.

Varying fan speeds are chosen by the ECU based on pulse widths and using inputs from other sources. When I was tuning, I could change the fan speeds based on what I needed to accomplish in a given tune. Here is an example of a fan speed data table in a tune. The ECU uses a base table then another one if AC is running. The numbers in the cells are percentages (0 to 100%). Fans are never set to 100%. The charts below are factory settings from a GM car, but all mfgrs are doing it like this.

 

Thanks to all for your help. I hope this lengthy post saves someone some time.

The problem turned out to be a bit more than just the fan control module. I installed the new fan control module (from Volvo 3rd party site) and the large fan still did not work. I checked the wiring diagram for the fan units to confirm that the PWM signal is common to both fans.

While disconnecting the fan control module for the large fan, I noticed that the brown/yellow PWM wire was loose and easily came out of the connector. All three wires are sealed for water protection, so this concerned me. Also, I wanted to confirm that I had a working fan control module, so I ordered another module via EBay and also ordered a PWM generator and test connectors for the fan module. All are shown in the pictures.

I checked the connector/harness on one of the popular parts sites, and it’s “available to order” and not in stock. Fortunately, I found one pulled from a Rapide on EBay and had it shipped to my house.

First step was to wire up the PWM generator and test connectors to my 12V supply and output to my multimeter to confirm I had a working fan control module. The Volvo aftermarket module did not work, and the fan control module pulled from the car only produced 7V when PWM duty cycle hit 92% while the EBay module produced 12V at 92% duty cycle.

Next step was to re-confirm that the large fan ran when 12v was connected to it.
Next was to connect the good fan control module with an external 12v supply and PWM generator to the large fan. The fan turned on at 92% at low speed and gradually increased speed as the duty cycle was reduced on the PWM module.

I decided to replace the fan pack harness p/n 8G43-9137-AC, which was a real adventure. My goal was to be able to replace the harness without removing any of the cooling lines, which were prominent around the harness. After quite a bit of wrangling from many angles, large screwdrivers guiding connectors, and working from both the bottom and top of the car, I was able to replace the harness. The most difficult part was disconnecting and re-connecting the input to the small fan module as it’s very tight. Fortunately, the radiator is on rubber mounts and moves a bit to provide space to re-connect the module input. Another difficulty was the connector just to the left of the driver’s headlight, where the harness connects to the main harness. I had to loosen the power steering reservoir and push it aside as well as the crash detection sensor.

Once everything was buttoned up, I started the car, and both fans now run. I warmed up the car and took it for a short drive in the 111 degree Vegas temperatures. The temperature gauge was rock steady in the middle as before.

I’m going to order another module from the Volvo after market source and test it and have it on hand in the event I need it. Also, I’m going to pry open the original module to see if I can see what the issue could have been.

Now to call the dealer and cancel the $3,000 fan unit.

Jim

 

Excellent work diagnosing this issue.....hats off to you!