How to do the DeLorean Fan Fail Unit, fused jumper fix

My 1983 DeLorean oddly enough had the original blue fan fail unit still in the relay compartment. From what I have understood, almost every owner, not concerned with concour, has replaced it with a jumper wire, it was even a service bulletin from DMC in the 80s applying this at the factory, and instructing owners to do so. Even better than the jumper, is a fused jumper.  You can also replace it with an actual working unit, like the one Dave McKeen provides. The original problem is that the fan fail unit, which is supposed to alert you if one or both fans does not work, never actually was a reliable solution. The blue relay itself was quite a piece of engineering at the time, relying on two magnetic fields inside the relay, but since the fans were replaced by one team to fans requiring more amps, but not informing the electrical team, the fan fail unit simply never worked. Below I have put together some instructions for how to make and install the fix. Here are some other sources, describing it.

Edit: I have since this was written actually purchased the Solid State Fan Fail Unit and also the Solid State Fan Relay from Dave McKeen, but not yet installed it in my car.

Here is an image showing the instalment of the original un-fused jumper. The fused one simply adds an inline 20 amp fuse in each of the “legs” of the jumper. Additionally you can add a third wire to the B connection and stick the other end into the connection between A and C. This makes the Fan Fail Light in the instrument cluster come on whenever the fans are running. You can read more in the link below.

Here are the best instructions I have found on how to make the fused jumper wire.

This is the original blue Pektron Fan Fail unit which was still in my car when I purchased it on nov 2017. According to every advice i have read, it needs to be replaced by a fused jumper wire.
The back side of the Fan Fail unit. To replace this one, you need to fabricate a jumper wire, preferably fused, according to instructions.
This is my finnisehed fused jumper wire. It is made out of two inline fuses from eBay, with 20 amp yellow fuses. On one end of each wire, I tinned the wire with solder, and crimped a blue spade connector on it. The other two ends I soldered together with an additional piece of wire so that 3 wires go together in one spade connecter. You probably have to strip some of the strains of each wire to make them fit the connector. Finally, on the other end of the third wire I added another blue spade connector. According to the description in the link above you insert the end with the 3 wires where to power enters the relay socket (B in the diagram above, the connection closest to the passenger seat), and attach each end of the legs to the left and right fan (A and C above). The final wire goes from B in the diagram above to the middle connection, to make the fan fail light come on overtime the fans are running. You can then just cover the “fail” part in the instrument cluster.
My finished fused jumper wire from another angle.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s