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Doug In North Carolina
Doug In North Carolina, ASE Certified Technician
Category: Jeep
Satisfied Customers: 302
Experience:  ASE Master Mechanic, 12 Years Experience Specializing in HVAC, Electrical and Driveability Problems.
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I have a 2004 Jeep Liberty with 3.7L engine, 72,000 miles.It

Customer Question

I have a 2004 Jeep Liberty with 3.7L engine, 72,000 miles.It has DTC p 481, cooling fan control 2 circuit. The fan won't run when engine reaches operating temp. If you turn on the A/C it takes at least 3 minutes for the cooling fan to turn on {203 degrees}. The fan runs about 5 seconds shuts off, it will cycle like this when it wants too. I have checked the voltage at the engine temp sensor .842 volts @ 203 Degrees. I also swapped relays with the fan blower works on that circuit fine. I diconnected the electric fan harness plug at the shroud, I ohm tested for the grd wire at the motor, made the purple wire hot and the fan motor ran, I made the other purple wire hot, it would not run. I need some advise, Riffle
Submitted: 4 years ago.
Category: Jeep
Expert:  Doug In North Carolina replied 4 years ago.
Thanks for using Just Answer, my name is Doug.

Try doing a resistance check on the motor itself. You'll have to be patient and slow but hook your meter up to both leads and slowly spin the fan and watch for a dead spot in the fan. I'm working off of an 03 wiring diagram so bare with me if the colors don't match. Here's what I have:
-Dark Blue/Pink should be hot all the time, it comes from Fuse 2 (40amp) in the PDC
-Light Green is the radiator fan relay control (The pcm provides a ground on this circuit which then energizes the relay)
-Yellow- Radiator fan output, should be battery voltage when the relay is energized
-Black/Orange is the ground for the radiator fan as well as the fan relay.

If you have an amp meter that can handle a 40 +/- amp flow then I would also recomend checking the current flow through the fan both while it's running as well as at initial start-up (It takes more current to get it move than it does to keep it moving).

Also, I'm looking at a picture of the fuse/relay box under the hood and I see a relay for the blower motor but that is not the same as the cooling fan relay. Which one did you swap and where did you find it?

Let me know,
Doug
Customer: replied 4 years ago.
Doug, I will do the resistance check, and also check the wiring color code for the motor, I will also try to wire in a amp meter for that check also. I checked the relays, both hi/lo electric fan{2 each} and the inside blower motor{1 each} have 40 amp relays, both of these feed through a 40 fuse, they also have the same numbers on the case. I had assumed the electric fan has two speeds is this correct? Is it possible for the motor to be shorted out on one speed and still not blow the 40 amp fuse? I guess the relay is taking the first jolt. I appreciate your info, I will need to get back with you tomorrow. I have not used this site before, will it be easy to get back in touch with you? Thanks Robert
Expert:  Doug In North Carolina replied 4 years ago.

OK, I'm looking at a diagram of the power distribution center which is where your relays are located. I was incorrect last night in my assumption of the fan relay location. On previous models they use a relay that is mounted to the frame rail but in yours there are two relays in the PDC. I will gather some more information today and help you out this evening. If you need help sooner then I will opt out and your question will automatically be resubmitted for another expert to assist you sooner. I can keep tabs on how you'd like to proceed, but I can't get a lot of time to help during today, it's been real busy at work.

 

You should get an email each time I respond to your question.

Doug

Customer: replied 4 years ago.
Doug, I will wait for your update info, there is no need to opt out. Robert
Expert:  Doug In North Carolina replied 4 years ago.

Robert, thanks for hanging in there for me. I've been thinking on this off and on today and wanted to verify a few things.


-2004 Jeep Liberty, 3.7L Gasoline Engine

 

Is your complaint the check engine light coming on or an overheating condition?

 

Also, I looked over the 03 and 04 wiring diagrams for the radiator cooling fan and both show the ground for the fan being on a Black/Orange wire at the fan. The power for the 03 is provided on a single wire that is yellow. The 04 year model gets power from the low speed fan relay on a Dark Green wire and the high speed fan relay provides power on a Yellow wire.

 

I'm trying to verify your concerns but also verify what wires you are working with because they don't match things on my end. Let me know what you can come up with and I'll be ready to help some time after 6pm.

Thanks,

Doug

Customer: replied 4 years ago.
Doug, the check engine lite is on with codes 480 and 481. My daughter is complaining of a low horn type beep during idle and one time after engine was turned off. I know the engine will overheat soon if I don't fix this problem, I've seen the temp run 211 degrees according to my OTC scanner. The wires I described were on the fan plug side, the harness side colors are correct Blk/org is ground, yellow is hi fan, dark green is correct for the remaining wire. I have traced both blk/org and yellow, these go to the hi fan relay. I did not trace out the green wire for the lo fan relay. I rechecked the voltage {12.9} on the yellow wire with A/C on and operating temp of 205 degrees.Fan runs a few seconds and cuts off, then it comes on again runs a few seconds and off again. I did wire up a Stewart-Warner 60 amp meter in line and the hi fan pulls about 25-28 amp start up and run about 23 amps. I did notice a bearing noise during start up and shut down, I could also feel the bearing noise with my hand on the motor. I also made the lo fan wire hot today and the lo side is dead. I hope this info helps. Robert
Expert:  Doug In North Carolina replied 4 years ago.
ok, I just got home and it will take a few minutes to get all of my notes together. One thing I did find earlier today was that the fans are not designed to come on until 203. Keep in mind that the thermostat is probably a 195 degree thermostat so we're only talking about 8 degrees more before the fan comes on. The 203 degree information came from the service manual of an 03 but the logic should stay the same for the 04. I looked under the same section in the 04 but it did not provide ANY on/off temperatures.

In the meantime, I know that both of the codes you're dealing with can be caused by the relays being removed while the key is in the on position. To help determine the frequency of the fault codes being triggered, go ahead and clear the codes and then crank the jeep again to see what returns. Of course keep an eye on the temperature gauge but I'm curios to see how often the computer recognizes a problem.

I'll be back shortly.
Doug
Expert:  Doug In North Carolina replied 4 years ago.
Ok, here's what I dug up earlier today regarding the fan operation:



The fan is electrically controlled by the Powertrain Control Module (PCM) through the fan control relay. This relay is located on the left wheel house in the engine compartment.

OPERATION
The electric radiator cooling fan is controlled by the Powertrain Control Module (PCM) through the radiator cooling fan relay. The PCM regulates fan operation based on input from the engine coolant temperature sensor, battery temperature sensor air conditioning select switch and vehicle speed.

The fan is not energized during engine cranking regardless of the electrical input from the temperature sensors and air conditioning switch. However, if engine operation conditions warrant fan engagement, the fan will run once engine starts.

On vehicles NOT equipped with AC The relay is energized when the coolant temperature is above 80 °C (176 °F) , or battery temperature sensor above 12 °C (10 °F) . It will then de-energize when coolant temperature drops below 82 °C (180 °F) , or battery temperature sensor below -9 °C (16 °F).

Vehicles Equipped with AC In addition to using coolant temperature and battery temperature sensor to control cooling fan operation, the cooling fan will also be engaged when the air conditioning system is activated. The relay is also energized when, air conditioning is selected and coolant temperature is above 95 °C (203 °F) , or air conditioning is selected and battery temperature sensor is above 41 °C (106 °F) . It will then de-energize when air conditioning is selected and coolant temperature is below 92 °C (198 °F) , or air conditioning is selected and battery temperature is below 38 °C (100 °F).


So based on that it sounds like the cooling fan comes on at the right point. What you would need to find out is if the fan shuts off BEFORE it's supposed to (198 or below).

Additionally, I think what we're chasing here is going to be a bad fad. It's causing the noise under the hood and it can cause fan relay codes to pop up as well. Add to that the noise and play that you've found and it sounds relatively nailed down.

The starting amperage as well as running amperage that you've noted are fine. I've got a 40amp fuse listed for the fans and alot of times we'll see higher initial start-up current draw that neither pops a fuse nor causes codes. It's usually a dead short or sustained current draw that pops a fuse.

Let me know what you think and I will be on for a while if you need more help.
Doug
Customer: replied 4 years ago.
Doug, I could have set the P 480 code by pulling the relays, I can't tell you if I pulled the relay and set the P 481 code. The fan has never come on with the A/C in the off position, I will clear the codes as you have suggest. I can tell you this, I went down and bought a new relay, I let the engine thermostat open the temp was 198 degrees, While running I pulled the LO FAN RELAY and the FAN CAME ON! Plugging it back in didnot make a difference. This the first time this has occured, I will let it cool down and check again. If I can keep the cooling fan operating in the proper temp range thats all I want. I don't understand why there is a lo speed fan relay, the relay will not make the green wire hot. The fan will not run if you make the lo speed side motor hot. I will look for your email. Robert
Expert:  Doug In North Carolina replied 4 years ago.
The way that the circuit works is that both relays get power from the same fuse. There are no resistors between the fuse and the relay nor between the relays and the fan. The wiring diagram never showed the purple wires probably because it's serviced only with the fan and as such, the components are fan, engine bay wiring harness , relay, PCM and are meant to be serviced on those terms.
graphic

That's the diagram I'm working from for the 04 model. Based on that, I would be lead to beleive that any resistors that are used to provide a different speed are made in to either the single wire leading over to the Dark Green wire OR made inside the motor housing itself. Either scenario would still suggest the problem lies only on the low speed fan circuitry and fan replacement is required.

If you remove the fan you can split open the wiring and see if there is a resistor inline and put power to the low speed circuit AFTER the resistor and see if you have fan operation.

Outside of fan replacement the only other thing I could think to do is install a jumper harness joining the low and high speed fan circuits. I would recomend putting a diode inline to prevent the current from back-feeding to the low speed relay when it is not supposed to be energized just as a precaution. The only downside I see to this is the fan will always operate at high speed. Just a thought if you wanted to save a few bucks.

Doug
Doug In North Carolina, ASE Certified Technician
Category: Jeep
Satisfied Customers: 302
Experience: ASE Master Mechanic, 12 Years Experience Specializing in HVAC, Electrical and Driveability Problems.
Doug In North Carolina and 3 other Jeep Specialists are ready to help you
Customer: replied 4 years ago.
Doug, I will go ahead order a new fan motor assembly, I cranked the car up and let it idle, once the temp reached 205 degrees the fan never came on as it did the time before, I stayed in the car the temp climbed to 225 degrees and then the fan came on, it ran around one minute. The fan cut off, temp dropped down too 205 degrees then started back up again too 225 came back on again started the same cycle over again. This is well above the numbers in your previous email, do you think I should go ahead and change the temp sensor. I know I took a cold reading with the key on and the voltage was 4.08 {should be 5.00V}? I know you have done a good job at suppling me with the information. If you will comment on the fan cycling at the elevated temp and changing the coolant temp, I would appreciate if you will comment on these two areas. Thankyou I hope you have a blessed New year. Robert
Expert:  Doug In North Carolina replied 4 years ago.
Thanks Robert. I beleive what you're observing is that the high speed fan is coming on when it's supposed to and that if the low speed fan circuitry was good then the fan would have already been on. You could verify this by using a test light on the Dark Green wire when the temp climbs above the 203 range. The light should come on even if the fan doesn't.

I will leave this question open in the event you have additional questions with this problem you're having. Thanks for being patient as well as for the "accept". I'll be around most of the evening.
Doug
Doug In North Carolina, ASE Certified Technician
Category: Jeep
Satisfied Customers: 302
Experience: ASE Master Mechanic, 12 Years Experience Specializing in HVAC, Electrical and Driveability Problems.
Doug In North Carolina and 3 other Jeep Specialists are ready to help you
Customer: replied 4 years ago.
Doug, I accepted your answer back on 12/31 but I see the funds have not been withdrawn from the account. I want you to receive the money. When I click accept again , the progrm says I already have clicked "accept".. Robert
Expert:  Doug In North Carolina replied 4 years ago.

Robert, thanks for the accept. From what I'm seeing there were two responses that you "accepted" on 12-31-09. Please don't click accept anymore unless you feel the need to, according to what I can see, I did get paid and really appreciate it.

 

Were you able to fix your jeep with the information we gathered while working on it?

Doug

Customer: replied 4 years ago.
Doug,I ordered 12/30/09, a new fan motor by application Dorman {620038} and it came in but had a 2 wire connector, I will have to send it back, Auto parts Warehouse sent me an RA# XXXXX I reordered today from Advance Auto {local} $143.00, used the correct Dorman number {621017} to reorder the 3 wire fan motor. There seems to be some confusion about 2 wire and 3 wire fan motors on this Jeep liberty. If this one comes in wrong I will install a jump wire w/diode as you suggested till I can get the right fan. Dealer wants $512.00 +tax & ship, I gave the dealer the vin. and he came back with OEM# XXXXX Nobody has this fan locally. I am glad you received your money, hope you have a good weekend. If I need other advise, will contact you. Thanks again, Robert
Expert:  Doug In North Carolina replied 4 years ago.
OK, try giving advance or any parts store that number to cross-reference. Depending on the part that frequently can cross it. Thanks for the detailed update and I hope you're able to get the right one this time.
Customer: replied 4 years ago.
Doug, correct fan assembly came in yesterday {1/14}, I installed it, fan turns on with the A/C compressor as manual instructs. During extended idle the fan cycles at 219 degrees without A/C on. I would like to the fan come on at 210 degree level, however I know temp/battery sensors discussed earlier tell the computer when to activate the fan motor. There is that intermittent "burrrrrr" sound for about 2 seconds when the engine is a idle, it made this sound one time yesterday, no codes are in system, drove the Jeep 100 miles last nite, with no problems. I can't thank you enough for your advise. I hope you have a good week. Robert
Expert:  Doug In North Carolina replied 4 years ago.

Thanks for the update Robert. Let me know if I can help in the future.

Doug

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