jeep58

I found that the cooling fan relay had a bad wire connection, The cooling fan goes on but does not seem to stop running " cycle on and off " What do you look for besides the fan rely I have changed that it is new, As I said fan goes on but does not seem to go off. Thank for any replies!

BlueRidgeMark

That's odd. The PCM drives the relay, so for some reason, the PCM thinks it needs to keep the fan running. That could be the temperature sender, or possibly the PCM has lost its mind.

Does the fan run all the time you have the key on? Or does it come on when it gets hot, and then won't shut off?

Funny, I was just looking the diagram for the fan relay, as I need to replace mine and I'm trying to figure out if I can use a standard automotive relay instead of the uber-expensive solid-state relay that Mopar used. (Yes, I think it will work. I'm going to give it a shot.)

Here's the diagram:

jeep58

Ok when the jeep is started the fan does not run, once it gets up to temp the fan kicks on it just keep running. I think that the temp sender in the thermostat housing is bad going to change that out tomorrow and see if it stops, The PCM is a remanufactured unit and I changed it out with another unit but same thing happens.

dave1123

The fan will continue to run on low speed until you shut off the engine. It doesn't start until it reaches 215*, then turns on and runs on high until the temp drops to 195*, but then runs on low speed until it either heats up again or you shut off the ignition. It cycles, but only from high to low and back again.

jeep58

Ok sounds good I had a lot of problems with the gauge light coming on, I found the connection to the fan wire harness spliced and tapered up with butt connectors green wire was loose connection fixed it and hoping that it resolved the "check gauge " problem !

dave1123

Many aftermarket fan assemblies are supplied with just loose wires and no connectors. I used heavy insulated spade connectors putting a male on one wire and a female on the other so if I had to remove the fan, I could reconnect it with the right polarity. I think that circuit is fused at 40 amps so the connections have to be good.

BlueRidgeMark

Like these. Male and female both insulated and made to fit together so that no metal is exposed.

dave1123

Exactly except! I bought mine at NAPA on the "Help" rack and they were blue for 14-16 ga. wire. I'm pretty sure the fan wires are bigger than 18-22 ga. They are fused at 40 amps.

BlueRidgeMark

14 gauge, I think. Might be 16, but it's sure not 18!

It's fresh in my mind because I just replaced my fan and relay.