Anyone know what this means: Alpha P Code of P1491 Secondary Switch Solenoid Circuit Mulfunction

Whenever it rains the engine light comes on my Dodge Grand Caravan and sometimes the radiator fans continue to run after I turn off the engine. They (2 fans) will run until the battery is dead. It never happens when it
is not raining. I swapped a couple of the relays around and the problem did not show up again. Yet a couple of days ago the engine lite came back on coming back to Dallas from East Texas in heavy rain. This time the radiator fans did not continue to spin and run down the battery when I turned the engine off, yet by the time I got home it was not raining. I took the Van to AutoZone and they read the computer code for me. They did not know what it means. In a previous post I was told it was the radiator relay under the aircleaner box but I cannot see any relays underneath there. All the relays appear to be beside the battery and a few under the dash, yet there is nothing labeled radiator fans in the bank of relays. Searching https://www.rockauto.com I did find some relays that almost look like the ones in the relay bank next to the battery. But what caught my attention was the one that looks like:
http://www.rockauto.com/ref/SMP/SMPDetail2.html?RY330.jpg
it is labeled "engine cooling fan relay": I am wondering if this is mounted on the chassis somewhere, maybe under the air filter box as I was told earlier. I have 2 questions:
1. Does the "engine cooling fan relay" mount on the chassis and if so where is it located, can I see it without removing the air filter box. 2. What does the code below indicate is wrong.
This is what the Autozone ticket says:
TroubleCode OBDII (Alpha) P code
P1491 Secondary Switch Solenoid Circuit Mulfunction Any ideas? Thanks in Advance...
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John Behneman
john (dot) behneman (at) gmail (dot) com
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The engine cooling fan relay is located on top of the left front frame rail at the front of the vehicle. I have never replaced one on a Caravan. I have replaced a few on jeeps and the bumper cover must be removed to gain access.

P1491= Engine cooling fan relay circuit. From what you mention above you have a failed cooling fan relay.

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"JohnB" wrote in message "Whenever it rains the engine light comes on my Dodge Grand Caravan and sometimes the radiator fans continue to run after I turn off the engine. They (2 fans) will run until the battery is dead. It never happens when it is not raining. I swapped a couple of the relays around and the problem did not show up again. Yet a couple of days ago the engine lite came back on coming back to Dallas from East Texas in heavy rain. This time the radiator fans did not continue to spin and run down the battery when I turned the engine off, yet by the time I got home it was not raining. I took the Van to AutoZone and they read the computer code for me. They did not know what it means. In a previous post I was told it was the radiator relay under the aircleaner box but I cannot see any relays underneath there. All the relays appear to be beside the battery and a few under the dash, yet there is nothing labeled radiator fans in the bank of relays. Searching https://www.rockauto.com I did find some relays that almost look like the ones in the relay bank next to the battery. But what caught my attention was the one that looks like:
http://www.rockauto.com/ref/SMP/SMPDetail2.html?RY330.jpg it is labeled "engine cooling fan relay": I am wondering if this is mounted on the chassis somewhere, maybe under the air filter box as I was told earlier. I have 2 questions: 1. Does the "engine cooling fan relay" mount on the chassis and if so where is it located, can I see it without removing the air filter box. 2. What does the code below indicate is wrong.
This is what the Autozone ticket says:
TroubleCode OBDII (Alpha) P code
P1491 Secondary Switch Solenoid Circuit Mulfunction"
You did not mention what year your van is and the motor size. I found some information that states on a 1999 Dodge Grand Caravan the relay is located under the air filter box and does not look like a relay. I also found that on 2001 Dodge Caravan that the relay is mounted under the front fascia on the drivers side and fastened to the top of the bumper. I also found this location description on a 1997 Dodge Caravan. What you are looking for is on the frame rail on the driver's side front by the radiator. It is a solid-state speed control although Dodge calls it a relay. It is black or gray and very small.I would follow the wire back from the fan to the relay to locate it.
Sarge
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Yes that is the fan relay and yes it is mounted on the frame rail as i told you before,
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