Cooling Fan Relay Control Signal. HELP PLEASE ! - DodgeTalk : Dodge Car Forums, Dodge Truck Forums and Ram Forums

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post #1 of 5 Old 03-01-2006, 03:43 PM Thread Starter
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Question Cooling Fan Relay Control Signal. HELP PLEASE !

Does anyone here knows what kind of signal I need to have from the ECM on the cooling fan relay pin for it to work ??
I have replaced the Relay (solid state module) when I ground the control pin on it, the fans work fine, but they dont work when I switch the AC on or when the engine is hot. I have checked the wiring and get a 1.8 ohm on the wire from the ECM, so I replaced it I get 0.3 ohms now which is a good contact I believe, but still it does not work.... All of this happened after I washed the engine....bad call.....
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post #2 of 5 Old 03-01-2006, 05:43 PM
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I would look for the coolant temp sensor to see if it didn't take kindly to a soaking. Just a guess. This oughta throw a code, too. Have you had your trouble codes checked?

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post #3 of 5 Old 03-01-2006, 05:48 PM Thread Starter
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Yes, I have had the codes read, I got P1491.
The coolant temp sensor that you mention, would it affect the way it is reading the temp on the instrument panel ? Because it is reading fine.
Or is it a separatre sensor ? THANKS!
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post #4 of 5 Old 03-03-2006, 09:58 AM Thread Starter
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Post coolant temperature sensor ???

How many temperature sensors does the caravan have ? The temp gauge is working, does this men that the computer should know when to turn the fans on and off ? THANKS !
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post #5 of 5 Old 03-03-2006, 06:06 PM
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The fan is tied directly into the temp sensor (1 sensor), to test the sensor remove the plug from the temp sensor and the fan should run, its on top of the thermostat housing and has a 2 wire plug. If the fan doesn't run your fan "Relay"or the AC switch may be the problem. Also check the relay for proper ground. The relay is grounded by its case to the fender so ensure theres no corrosion between them. The temp gauge is on a seperate sensor its beside the temp sensor on the thermostat housing and has a (1 wire) plug.

The AC is also controlled by the same system, with a switch added to the AC control panel in the cab, once you turn on the AC the fan runs automatically, if it doesn't again check the sensor. Remove the sensor and dry the pins out and use electronic cleaner spray to get rid of any access moisture. If that don't work, replace it.


1993 caravan SE 3.0L 3 speed 220,000 miles my second caravan bought new. over the past 13 years i've replaced: 1 fuel pump, 1 front crank bearing and seal, 3 timing belts & water pumps, 3 exhaust systems, 4 sets of sway bar bushings, 1 catelytic convertor, 2 sets of engine mounts, 1 set of front struts, 1 alternator, 2 batteries, 1 computer, 5 sets of tires, 6 sets of plugs, 3 sets of plug wires, 2 coils, 2 TPS, 1 IAC, 2 Speed sensors, 3 Map sensors, 2 Coolant sensors, 1 Drivers side door (rusted out) and countless oil changes.

2004 Grand Caravan 3.3L 46,000 miles. Picked up at an auction.
2005 Kia Sedona 32,000 miles "wifes van"
2001 Ford F-250 Quad cab (farm truck) 71,000 miles
1991 Honda si. (Gas sipper) Presently in the process of restoration 0 miles after restoration

1988 caravan 3.0L 3 speed, Finally drove her to the wreckers in 2002 with 297,000 miles on her. (May she rest in peace)

God sure made me handy with a roll of duct tape.

Last edited by Chet42; 03-03-2006 at 06:13 PM.
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