grobb284

iTrader: (9)

I'm using a single speed fan with my car, so I am using the ouput for the low speed fan from the PCM.

My question is, the control for the fan is a 70 amp relay, which may have a larger pull in coil. Any problems with PCM ground pull in with the higher in rush current for the coil? Wondering about longevity for the switched ground of the PCM. (wire DK GRN #335)

Will probably use a rocker switch in parallel with the PCM to also pull the relay to ground to have the fan on all the time.

Also using the same ground to pull in an LED on the dash to tell me when the fan is on. Thinking this indicator isn't enough current to worry about for the PCM.

Anyone have long term experience for the PCM with a larger fan relay?
Are you using any suppression (diode or resistor) for when the coil collapses?

LS1MCSS

iTrader: (18)

That must be one hell of a fan to need a 70 amp relay.

01cherryreds10

iTrader: (9)

Ford Mark VIII fans usually need a 70A relay for the initial spike in current. That's what I've got on mine. Can't answer the wiring question though

mantycarguy

The coil side of the relay is usually very low amperage. The switch side is what handles your 70 amps of current. This is precisely why a relay is used for this kind of circuit. Your pcm ground should be fine. Just make sure your wire size on the switched side is guaged correctly to handle to handle 70 amps of current. I would sugggest a #10 wire and keep the relay as close to the fan as possible.