I recently had my relay jumper device fail because of a bad crimp, so I have spent a lot of time recently with the electrical part of the cooling system while trying to locate the trouble. Heres a diagram of the relay connector:
1=GND 2=Right fan 3=Left Fan 4= Fan Fail Light 5=Power IN (on any time the IGN is on)
Facing the electrical access area from the passenger seat, you need to have a double set of FUSED jumpers that run from the power input of the relay at the bottom connector to each of the sockets on the left and right sides. Do NOT put anything in the upper center connector or you'll ground out the whole car. Buy 2 in-line automotive 20 amp fuses and crimp a blue spade lug onto one end of each fuse wire. Then solder the other 2 fuse wires together after you have thinned down a number of strands in each wire. Then crimp the soldered connection into a yellow spade lug. Since these crimp connectors are in themselves a point of failure, you may want to solder and crimp the wires on all the lugs. That's how mine failed. The wires were too big to both fit into the yellow connector so someone just jammed the wires into the connector and did a poor crimp. Using all the strands from both wires are too big to fit the Yellow spade lug (anyone ever seen a next size up from 'yellow'?). If you want to know when your fans are running, solder on 1 more wire and a spade connector from the power input of the relay and plug it into the connector just above the power input lug. Then, every time the fans come on, the 'Cooling Fan Fail' light will come on. Just use some black tape to cover the word 'Fail'.
What's best is to have the 'Fanzilla' kit from P.J. Grady. It's amazing how much of a load those 2 fans cause when they come on. Being rather broke at the moment I have not been able to buy one myself. Does anyone know if the construction of one of these devices is documented somewhere?
My passenger side cooling fan had broken. The small pin that goes through the shaft of the motor had broken off on both sides, allowing the plastic fan to slip back. The E clip that held the fan on the shaft vanished. I was able to fix it, but it did require a little creative machine work. The first thing needed was to pull out the remains of the old pin and install a new one. I was not about to pull the whole front radiator out to fix the fan, So I machined out a long punch to remove the rest of the old roll pin and to set in a new one. The punch was made to the exact size of the old pin and also has a holder in the back to assist in installing a new pin. I did have to drill a small hole in the shroud for the punch to pass through After getting a replacement E clip, I machined a special E clip tool to install it and it snapped right in! I was able to return the fan to service without removing anything. I could not have done it without the special tools though. It helps to have a full professional machine shop at my disposal! I expect I'm going to need to make MANY special DeLorean tools over time.