Keep frying electric cooling fan relays!

[LobsterThief]

Every time I put a new relay in the fan runs for about 10 seconds (when engine is hot) and then there are burn marks on two of the relay pins.

 

If I jumper the relay port (the ones going directly to the fan) the fan runs fine. I checked the connections inside the electrical panel and they seem good.

 

I have a '91 4.0 HO.

 

Any other spots to check? Thanks!!

[Jeep Driver]

Sounds like the fan has too much of a current draw........IOWs it's on it's way out.

[LobsterThief]

Is there a good way to test it with my multimeter? What's the acceptable range?

[HOrnbrod]

Unbolt the PDC assembly where the fan relay resides and look underneath at the relay socket. Check for burnt or partially shorted relay pin sockets.

[LobsterThief]

Turns out the aux electric fan had a hairline crack in it, so once I hit 45mph or so the wind would push it into the power steering pulley -- which damaged the fan, cranked up the amps and fried the relays. They really should've put a bigger clearance between the fan and power steering pump.

 

I had to jumper it to relay to get it home without overheating (I live in Florida) so I hope I didn't damage my ECU :( I got the fan problem fixed by replacing the fan but the Jeep's had a severe loss of power (and shifting problems) since that whole fiasco.

 

Expensive lesson learned!