I have a 08 Grand Caravan SXT with a 4.0 l v6. The cooling fan just stopped working. The van overheats when idling. At hwy speeds,it cools like a champ. Any suggestions before I shell out big cash at the dealer? I have heard about relays and what not but I don't know where they are located. I see one relay or sensor located on the radiator and one near the front of the van by the driver side headlight.
Thank you in advance

 

I would check the fan: unplug the connector at the fan and run jumper wires from the fan to the battery, the fan should turn on.
Then check the relay(s). If your '08 4.0 GC is like my '08 3.3L T&C, there are two relays - high speed and low speed. Take each relay out and check it (apply battery voltage to the control terminals and the relay should "click" and open/close the switched terminals).

Your van might have a solid state high speed relay? Those have a large heatsink on them. You probably won't be able to easily test that relay, and they have a reputation for being unreliable.

 

Thank you for your quick reply. One of the relays has two wires leaving it. I think this is the one with the heat sink. It has a few ribs on the front side. Are you telling me to apply 12 volts to each side of this? And if I jump these tow sides of the plug with a wire, shouldn't the fan run.

 

My van does not have the solid state relay / heatsink, and I don't know how to test those. The output is not a simple on or off, it is modulated to vary the fan speed. Regardless, if you disconnect that relay you should be able to apply 12V to the fan terminals and see if the fan starts.

 

Disconnect the fans and test them with voltage, as suggested. If the fans work, then you need to get some good wiring diagram of the fan operating circuit. Don't jumper power to stuff unless you have a clear understandign of the circuitry.

Jumper wires backfeeding components can result in failed computers and thousands of dollars of damage. It's not a job for novices with jumper wires and $5 voltmeters. Once fans are tested good, you need to use the wiring diagrams and factory procedures to troubleshoot the control circuitry. outputs from computers must be isolated (disconnected) when using jumper wires to avoid making a $100 repair into a $1000 job. Possible areas of possible trouble would include fan relays, connectors, wiring harness, temp sensors, computers etc. Troubleshooting would systematically rule out all wiring, sensors and relays before blaming the costly computer. You should be able to test the input and output from the computer associated with fan circuit activation, if you know exactly what you're doing.

At that point, you need to bend over and visit the dealership for final diagnosis and repair, even if you're an experienced electrical control engineer with a set of ebay $200 factory service manuals. This is because not one aftermarket company offers preprogrammed computers for the '08 and up caravan via reman exchange or otherwise. They seem to have given up after the 2007 model year due to complications with WIN module rolling key immobilizer circuitry and such. You need facotry programmers and the vehicle present to replace a computer. There's too much cross-checking & hand-shaking going on between the various computers in the '08 and newer van to do any backyard mechanic computer swapping. Salvage yard computers aren't worth a dime for troubleshooting, swapping or repair, even if the van has identical options to yours. It will NEVER start unless you simultaneously swapped out every single computer and the fobik.

PS: Maybe wire the fans to the horn circuit. You could just blow the horn for a couple minutes when it gets hot lol.

 

First of all, thank you for all your advice and thorough answers. You made me laugh with the horn but then I ... Maybe... But I don't trust my wife to remember.
I may have an idea. I plan to purchase the relay from a local parts store and swap it out. If that's not it I'll see if they will take it back. If not its only $52.
I think it's worth the risk to blindly swap the relay since its the most likely culprit. And testing other elements sounds confusing.
I'll keep you posted.

 

I promised to keep you updated. I just didn't know it would be so soon.
I disconnected the battery to take the relay off and see how hard the relay would be to replace. I disconnected the relay and reconnected it and reconnected the battery.
I started the engine and went to order the part. On the way I decided to test the fan and heated the engine by driving it with a little extra pressure on the skinny pedal.
When I came to a stop, I heard the fan blowing.
I have restarted the engine a few times and the fan works ... for now.
It could have been a faulty connection or disconnecting the battery may have helped. Or the relay could be faulty and functioning periodically. I will keep a close eye on this one.
Thank you again for your help.

Now I have to decide if my wife driving a van that is faster than my truck makes me less of a man or makes her more sexy.

 

Need help on 2008 T&C touring with the 3.8. Had a radiator leaking so I replaced it with a new one from the dealer. After I install it I took it for a test drive and noticed that it was running hotter than I remember. When I got home ,with the engine still running, I open the hood and noticed that the cooling fan was not on. I found both relays and checked them ,out of the car, with battery voltage and the relays clicked and contacts closed. I also applied batt. voltage to the output contacts of both relays and the fan operates as it should, low and high speed. Also the low speed did click on, after a few cycles, of the A/C being turned on. I'm thinking that something is wrong and that may be why I had to replace the rad. But don't know where to go from here. Thanks in advanced.