Another Fan question - Coyote engine

[CalR80]

On my drive to the HB show his past weekend and hit the famous LA traffic.... Coming from Northern CA the engine was cool but once in the stop and go of “The 405” she started to get pretty hot. I found the electric fan, which is controlled by the engine control box, was not working. The “fan” light was on. Stopped at a Pep boys and managed to rig up a temporary switch to get the fan running.

The Huntington show was awesome and meet some great guys.

Back home now and am about to dive into this repair. I have read that there is a fan fuse in the control box. Does anyone know if it is possible for the fan light to be on with a blown fuse in the control box?

Dave

[TheBabyBadger]

Depends on the pathing for the wiring. I'd say YES. If the fan control wire from the ECU/engine control box, then runs to the fan light, then to the relay (or vice-versa), then relay could be bad (on the supplied power side to the fan) but still turn your light on. If your light is coming on, I'd start by 1. checking the relay and the 2. checking the way the relay is wired. If you wired a "fan switch" you've already removed the fan itself from the equation. If you give me a diagram or more info on the wiring I can be of more help!

God Speed!

[edwardb]

Exactly right. Depends on how the light is wired. You don't mention Gen 1 or Gen 2 Coyote. The Gen 1 PDB has a fan indicator light on the PDB, so maybe that's what you're talking about? Or a separately wired indicator light, which would be the only thing possible on a Gen 2. Either way, it's possible the light could be on but the fan not receiving voltage. Sounds like the fan itself was OK since it ran with direct power. Both Gen 1 and Gen 2 have a fan fuse and fan relay in the PDB. That's the most obvious culprit. I've put a fan indicator light on the dash of my builds, and power it off the +12V lead to the fan motor. The light will only come on if the fan is being commanded to run. It the light's on and the fan isn't running, then I know it's the fan itself, although they're typically pretty reliable.

[CalR80]

It is a Gen 1, and I am referring to the fan light on the PDB. It was on but the fan wasn’t.

I will take a look at the fuse first then.

[TheBabyBadger]

Fuse and relay, since fan works. Relay can be internally faulted, ie not magnetizing to pull switch.

[frankeeski]

For the 4.6 mod motors and the early Coyote engines, Factory Five had 2 methods to wire the fan. One had you wire the fan directly to the fan, bypassing the fuse and relay in the Ron Francis Chassis harness. The second method had you running it through the Ron Francis fuse and relay. Depending on the draw of the fan, you could have easily blown the fuse in the secondary system (Ron Francis harness) look under the dash for the fuse that runs the engine cooling fan.