Diagnosing P1491 Radiator Fan Circuit

1999 Plymouth Grand Voyager recently had SES light indicate a P1491 code. This code transates to the Radiator Fan Circuit.

I presume this means a bad relay, fuse, or motor (although less likely could be bad wiring). I haven't checked the shop manual yet to determine how accessible each item is, or, if the correct voltages are listed.

Has anyone any experience checking this? Is there a best method to test/repair?

I had a similar problem with my van. On mine, the fan would not turn on once it reached the tempature at which it SHOULD come on. I determined that it was the radiator fan switch by doing these steps:
1. Locate the switch, near the bottom of the radiator fan.
2. disconnect the wiring/power supply from the switch.
3. in the end of the plug that you just removed, there should be
slots, similar to that of the female end of an extention cord.
4. DISCONNECT THE CAR BATTERY, and then take a small section
of a wire coat hanger and bend it into a "U" shape.
5. Carefully insert each end of the "U" into each opening in the
plug. Doing this will actually bypass the switch in the fan.
6. Let the rigged plug dangle freely, and connect the battery
again. Once the battery is connected, simply turn the ignition
into the "on" position, and if the radiator switch is the problem,
the fan should turn on.

By bypassing the radiator switch and causing the fan to turn on, we have determined that the switch is the problem, because once the switch reaches a certian tempature, it completes the circut with the plug and turns the fan on; much like a thermostat. If the thermostat in the switch is stuck or no longer active, it won't complete the circut when the tempature is reached, causing the fan to not come on, causing the van to make a huge scene with all kinds of smoke coming from under the hood. Good luck with the test, and just for the record, the radiator switch is 11.98 at Auto Zone.

hi all,
had same problem with a 1999 plymouth voyager, first thing i found was a blown radiator fan fuse in the pdc under the hood. Checked the fans by spinning them to see if they spun freely, which they did not...excessive current draw by the bad fan motor cause the fuse to blow and set p1491 - radiator fan control circuit. Only the driver side fan was tight to spin however i replaced the whole assembly to assure my customer that there would be no other problems with the other fan as well. hope this helps someone!
ASE Certified Automotive Technician - Zack

Request to Bikerbob:
>>the radiator switch is 11.98 at Auto Zone
I did not find that part in my radiator fan cooling circuit,
parts found were:
fan motor,
fan relay
thermostat
temperature sensor
Please be more specific to name & describe the part you mentioned? Do you have the Autozone part#?

Request to Bikerbob:
>>the radiator switch is 11.98 at Auto Zone
I did not find that part in my radiator fan cooling circuit,
parts found were:
fan motor,
fan relay
thermostat
temperature sensor
Please be more specific to name & describe the part you mentioned? Do you have the Autozone part#?

I don't think Bikerbob will be responding any time soon to your request. He posted that post in April 2004, more than 5 years ago and hasn't been back since. This is the reason why we ask members, especially newer members to check the date(s) of the posts before replying. Many times the posts are so old the member is no longer active on the site. We try to discourage the resurrection of older posts as is in the case of this thread being brought back up this past summer, for this very reason. Rather we request that members start a new thread to ask a question or address an issue and they may link to an older thread if it is related to what they are posting.