01 Grand Cherokee Limited is overheating

My '01 Grand Cherokee Limited is overheating. I have changed the thermostat and ran a leak test. I am not having a leak. The temp drops when I turn on the A/C or heater. I went back to the shop that changed the thermostat and leak test. They said it was the fan control and I have to go to the dealer to reflash the program for the fan control. I made the mistake of asking the dealer to reflash, instead of having them check on the overheating problem. I’m planning on going back to the dealer to have them diagnose the issue. Does anyone have any recommendation?

Does the fan come on when you turn on the AC? Does the other fan come on when your idling and the engine is up to temp?


What engine do you have?

Is this what the dealer did?


The 2nd fan comes on when I turn on the AC or heater. Otherwise, I don’t think it’s coming on. I have the 4.7 L engine.

I was told that there is a solenoid in the power steering that turns on the fan. I know that my steering wheel seems to turn a little more than what the tires are doing when i’m driving slow with full turns like in a parking lot. I’m not sure if that has anything to do with it.

db4690: yes, the auto shop thought it might be the PCM so recommended for me to go to the dealer to have the software reflash. i mistakenly asked the dealer to reflash the software, instead of diagnosing the issue.

Does it overheat while driving down the freeway or only during low speeds and when idling, like when going through a drive-through window at McDonalds? If it overheats at low speeds or drive-throughs, next time it does it, take a look at the radiator cooling fan. It should be spinning like a banshee. Is it?

Well, you most likely have speed sensitive power steering . . . that means the slower you go, the more assist you get. You should get maximum assist at parking lot speeds

A solenoid in the power steering turns on the fan? I guess this is possible, but I’ve never heard of that function before. On many vehicles there is a solenoid in the power steering pump, but it doesn’t turn on the fan, it increases the idle speed.

There is a temp sensor that turns on the fan during normal operation. The other fan that operates with the ac is normal. Does the normal fan come on? If not it’s either the fan motor or the temp sensor. If it cools when you drive, then it’s probably the fan or sensor. It could be the thermostat if it does not cool at highway speeds.

Begin with a combustion leak test to determine if there is a bad head gasket.

Sounds to me like a bad fan relay. I had the same problem. The fan would work if the ac were turned on, turn it off and no fan, car would over heat. Normally you would get a P1491 code. But I think if the ac turns on the fan it doesn’t post a code. For more info Google Jeep Fan Relay. A common problem.

DJet: thanks for the suggestion. There’s a youtube for the simple way to get to the relay. it does involve doing a little surgery after you take the right headlamp out. I’ve done surgery to get to the blend doors so I’ll give it a go.

Hi all. I just want to follow up. I had the Jeep dealer diagnosed the issue. They said I have a “flow problem with the radiator flow.” They are recommending replacing the radiator and hoses for $1125. ouch! I’m holding off doing the work for now.

Please try an independent mechanic. I’ll wager they can do the job for far less.

Yes, definitely. A recommended shop is almost 35% less than the dealer.

If the combustion leak test is negative go directly to a new water pump. The 4.7 has an issue with the impeller slipping on the shaft due to a design flaw. Very difficult to diagnose because the resulting impeller slippage causes intermittent LACK OF COOLANT FLOW

Thanks for the tip.