The weather hasn't been really got yet but when I'm going through a drive thru say at McDonald's if there is a huge line up the heat rises and I can smell the coolant heating up.

My question is would a non working relay in the ecu box for the water pump, would this cause the fan not to turn on?

 

ECU will throw a fault for a POPed fuse, or relay issue.... ECU can pick up circuit problems...... No check engine light, no relay problem...

 

Thanks for that response saves me alot of time trying to figure it out,

When I use my vagcom and do the coolant fan output test nothing happens at all/ no relay clicking nothing.

Is my primary point still the fan module if the fans do spin?
Is there a fuse I am missing that triggers the fans off?

(no check engine light if a fuse did go)

 

We charge $$ per hour for the info that is in this post

read the post again.... the answer is in here

You need a FAN Control Module

 

Sorry just wanted to update I took it to the mechanic they said it was the fans it self but I'm not so sure about that.

My last question is wouldn't a fcm cause a fault to show up in vagcom. Thanks for the help big time

 

nope, but a fan that shorted to ground could smoke the fan control module. Usually the fan control module just goes dead, no faults or codes in ECU or 01 and no fan operation.

 

your mechanic just wants more money to replace the whole setup. Replace the fan control module and be done with it! Very common problem with these cars. Just google it and see for yourself.

 

I have a similar problem with the exception that OCCASIONALLY my fans will actually start running AFTER I have shut the car off and started to walk away. Unfortunately i can not tell you whether or not the check engine light is on because of this issue... its been lit up for awhile now because of the cat. On cool days, the AC runs just fine (when moving) and the water temp needle never strays beyond the middle mark even at idle... but now that its getting hot down here its getting dang uncomfortable sitting at idle and very unnerving when the coolant starts to rise if i dont get moving quick enough! So... your opinion would still be the fan control module (with my exception of the occasional fan running) ?

Thank you in advance for your input. You guys are awesome. Wish i had an Audi mechanic in my part of the world that I could actually trust that they knew what they are doing.

 

^^
I had this problem for sure it's the relay in the ecu box probably water got in it corroded the fan relay in it for the after shut off fan issue or even the temp sensor for the other issue

 

Can any one tell me what relay is the cruse control for an a4 2.0t quattro 05