clicking radiator fan relay

Joseph Yakubik JYakubik at
Thu Sep 11 22:37:20 EDT 2003

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Joe Yakubik

-----Original Message-----
From: Joseph Yakubik [mailto:JYakubik at]
Sent: Thursday, September 11, 2003 9:23 PM
To: '200q20v at'
Subject: clicking radiator fan relay

I've just sold my '91 200TQW and the radiator fan relay (#3 in the fuse box)
has started cycling.  The buyer hasn't picked it up and I want to fix this
before he does.

Symptoms: rapidly cycling or clicking relay when the ignition is on (motor
running or not) AND the A/C is off or ECON.  The fan also spins very slowly
when this happens, so it is getting power from the cycling relay.  It didn't
do this prior to my installing a new radiator fan yesterday.

I've searched the archives and haven't found a solution I can use.

Since the clicking stops when the A/C is on, I assume it's getting a cycling
ground signal through the other leg of the circuit (turbo coolant pump
control unit).  I thought I might have bumped a wire or a sensor during a
radiator fan repair, so I double checked those sensors.  Observation: relay
clicks with or without radiator cooling fan or turbo coolant pump temp
sensors connected.  Fan & pump runs when sensors shorted, so I assume
they're good since disconnecting them doesn't stop it, but shorting the
circuit path makes the fan operate normally.

I followed the circuit path in the Bentley and did some more troubleshooting
after checking on-line.  There's a similar problem described here:

Since it didn't appear to be the cooling pump, I followed up on the injector
temp sensor side.  I can't find the specific wire/sensor mentioned on-line
but after selectively pulling a few fuses, I've pretty much got it isolated
to a problem on that side.  The clicking will stop if I pull either fuse 24,
27, or 28.  I assume this means there is some fault in the injector cooling
circuitry or possibly the ECU.  I pulled the temp sensor wires (two-wire
fitting) on the back of the passenger side of the block (Bentley says
coolant temp sensor) but this didn't help.

Any BTDT's?

The car's going to the mechanic on Monday to get a new belt/water pump prior
to its road trip.  I need to get this fixed soon.

Joe Yakubik

JYakubik at

About to be Audi-less after 9 years


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