QuestionOur 2001 Chrysler Voyager with 65,000 miles on it has problem with engine cooling fan. We have replaced the fan relay switch 2X as well as the Intelligence Power Module for fans. The cooling fan runs when the car is parked and drains the battery. It doesn't matter if it is cool or boiling hot outside. After the 2nd relay switch was replaced (thought maybe the first was defective), the car drove fine for about 5 days until the fan started running again and drained the battery. Please help.
AnswerHi Pat,
The latest van manual that I have is for '98 so I can't be sure whether what my circuit applies to your later model. Mine shows there to be a single relay that is mounted on the left side frame rail just behind the lower left corner of the fan module. It is "solid state" and there was a recall on this module in the latter 90's, so it must have a tendency to fail, probably due to overheating.
It has a plug with four wires; gray is the one that carries the current from fuse 24 (40 amp, but in any case it will probably be the only 40 amp fuse even if not in position 24) in the electrical power box under the hood near the battery to the relay switch.
Now either the relay is stuck closed (in which case with the plug removed you could measure continuity (0 ohms) between pin 4 (where the gray wire attaches) and pin 3(where the dark green wire attaches. If that is what you find then the relay has gone again. If on the other hand it is open (infinite ohms) then that part is ok, but instead there is a fault with the wire that controls the relay, the light green/dark blue wire that attaches to pin 2. With the ignition off, that wire should be floating (infinite ohms compared to ground, any shiny chassis surface) and it should remain that way with the engine running and the temp of the engine below normal operating level or the AC not in use. If you activate the AC you should detect a grounding of that wire by the engine controller, or if the temp of the engine reaches normal it should also be grounded. I am assuming that the relay actuation coil is provided with 12V on one end by fuse 24, and that the controller merely ungrounds or grounds the other end of the coil to open and close the switch. You could check to see if instead you either have 0V or 12V on the wire from the controller as an alternative wiring scheme, and the other end of the coil would then be grounded all the time via the relay external surface. In that case you should not see 12V on the light green/dark blue wire until you tried to activate the AC.
It is stated that the relay has to be firmly attached in its bracket and the bracket firmly attached to the frame or the heat created in the relay can not dissipate and thus damage it. So check the mounting situation of the relay if you find in to failed with the switch in the closed position.
As an emergency shut off to save the battery, just remove the 40 amp fuse in the power box under the hood.
I will be curious to learn what you find out.
Roland
