cooling fans

Hi all, Newbie here and really like the site. I was hoping someone could give me some assistance. I have a 96 Voyager 3.3 with neither fan working. I have verified the fans by jumpers, checked the resistance variation at the cooling sensor, and replaced the relay. It is currently popping a P1491 and will not clear. Someone had previously spliced in a new connector for the relay and I need to verify the wiring. Below is what I have at the relay and wanted to verify this is correct.

Black Ground to fans and chassis, 0 VDC

Drk Grn Power to fans, thicker gauge, 0 Volts out of relay

Lt Grn/Blue From PCM, thinner gauge, 12 Volts output from relay (I verified this by cutting the wire and measuring the PCM side, then the relay side. Only the relay side had 12 volts.

Grey Thicker gauge, constant 12 volts

I have tried to reverse the dark green and lite green to give the fans 12 volts output from the relay but this did not work. I have checked resistance of all wires and found no shorts or breaks.

I can only tell you how my 2001 is setup. It's probably the same for you but no guarentees. The radiator fan relay should have 12 volts from pin 1 to ground at all times. You should have 12 volts from pin 2 to ground when the relay is activated. Pin 4 is the 12 volts from the PCM to the coil of the relay, only present when the PCM says the fan should run(***). Pin 3 is the ground for the coil of the relay.
To check: If you know the fan should be running, connect a voltmeter from pin 4 to a good chassis ground. You should read 12 volts. If you don't then the PCM is not telling the relay to start the fans.
If you have 12 volts, then: connect the voltmeter to pin 4 and pin3. If you read 0 volts then you have a ground problem. If you have 12 volts then the coil is good. If the coil is good, and if you have 12 volts to ground from pin 1 of the relay, then measure voltage from pin 2 of the relay to ground. If you have 12 volts, then you have a bad fan motor(s) or the wiring from the relay to the motor(s) is bad. If you have 0 volts from pin 2 to ground then the relay is bad.



***If you never get 12 volts from the PCM then you probably have a bad heat sensor or wiring from a sensor. Remember: "Grounds are important for all components and often the problem".

I have a 96 Caravan and had the fan relay replaced under a recall. Once they replaced the relay both my fans started working again.

B33P3R wrote "If you have 12 volts then the coil is good."


I assumed by coil you meant the relay? I will try and retest using this method. Do both fans run during a.c. operation or just one? Thanks again.