512 TR cooling problem

Run 12 volts directly to the fans to be sure they work. If they do,then it is likely the fuse box which is a common problem in Boxers and TRs.

 

At the schematic?

Let's hope we don't go there, but if schematic-less:

1. Unlup and replug the 4 connectors along the bottom edge of the fuse/relay panel (a.k.a. "fuse box" per Frank's post) -- check for "extreme frazzledness". If no obvious problems, do the rest -- but be aware that some of the bigger red lines will be at +12V if you don't disconnect at the battery switch.

However, your report that both sides are inoperative (and since the architecture has an independent relay/fuse for each fan motor), I'd think trouble further upstream (unless you've had one side dead for a long time, and now when the second side died you finally noticed something was amiss). If #1 looks good with no obvious problems, try:

2. remove the radiator fan motor relays, key "on", short the thermoswitch in the radiator closed again, and measure the voltage between the 85 female terminal and the 86 female terminal socket on each radiator fan relay socket -- should go +12V.

Just some suggestions -- good luck...

 

Forgot to add 1 other quicky test:

3. With the relays removed and the key "on" (and the battery hooked back up), touch a jumper wire from the 30 female terminal of the relay socket to the 87 female terminal of the relay socket -- if all is OK, the corresponding fan motor should run.