2003 Jeep Grand Cherokee Laredo - Tech question

2003 Jeep Grand Cherokee Laredo - Tech question

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  1. #1
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    2003 Jeep Grand Cherokee Laredo - Tech question

    Ok, I have a 2003 Jeep Grand Cherokee Laredo. It is the 4.0 Liter IL6. There is a known issue with them and failing fan relays. I have had the car for about 2 years, and have had to replace the relay 4 times now. About every 6 months or so. It just failed again today, this time only 2 months after the last one. On the Jeep forums, everyone just seems to think it's ok to just replace it every 6 months when it goes bad. It is only a $35 part, but still. Has anyone else ever experienced this, and what did you do to fix it? I cannot find an actual solution to the problem other then keep fixing it.
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  2. 06-07-2008, 10:49 PM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

    If it's just a relay, replace it with another kind, not the stock one. Check the other models and see if there is a drop in replacement that isn't that failure prone. If there isn't, get a better quality relay from a different brand car and start wiring. There isn't anything magic about a relay; as long as it can handle the temp and current for it's intended application then it will work fine..
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  4. 06-08-2008, 12:22 AM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

    Quote Originally Posted by Fabrik8 View Post
    If it's just a relay, replace it with another kind, not the stock one. Check the other models and see if there is a drop in replacement that isn't that failure prone. If there isn't, get a better quality relay from a different brand car and start wiring. There isn't anything magic about a relay; as long as it can handle the temp and current for it's intended application then it will work fine..
    I think I have tried at least 3 different brands. The OEM, one from Napa, and several from Autozone.

  6. 06-08-2008, 10:11 AM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

    Quote Originally Posted by Paul View Post
    I think I have tried at least 3 different brands. The OEM, one from Napa, and several from Autozone.
    i only use the mopar one, although the NAPA unit is a reboxed OEM part. NEVER use anything from AZ for electrical.

    Quote Originally Posted by Fabrik8 View Post
    If it's just a relay, replace it with another kind, not the stock one. Check the other models and see if there is a drop in replacement that isn't that failure prone. If there isn't, get a better quality relay from a different brand car and start wiring. There isn't anything magic about a relay; as long as it can handle the temp and current for it's intended application then it will work fine..


    this is a PWM controlled relay, they have a penchant for burning up the drivers if there is too much draw. its basically a solid state relay. will set a CEL and cause multiple other issues if you try to rig in a standard ISO relay.

    Quote Originally Posted by Paul View Post
    Ok, I have a 2003 Jeep Grand Cherokee Laredo. It is the 4.0 Liter IL6. There is a known issue with them and failing fan relays. I have had the car for about 2 years, and have had to replace the relay 4 times now. About every 6 months or so. It just failed again today, this time only 2 months after the last one. On the Jeep forums, everyone just seems to think it's ok to just replace it every 6 months when it goes bad. It is only a $35 part, but still. Has anyone else ever experienced this, and what did you do to fix it? I cannot find an actual solution to the problem other then keep fixing it.
    they fail for a reason:excessive current draw. every one that comes in and i diagnose as needing a fan relay gets a current ramping done of the fan, and almost every one of them has a fan that is going out drawing too much current.

    it is very common for them to need both a fan and the relay, and i have never had one come back for repeat failure. not only on the grand cherokees, but also on the caravans.

    it really bothers me that there are so many techs out there that do not bother to check the current draw of a circuit to determine why something failed, instead of blaming "inferior parts". and yes, most dealer techs do not even check the fan draw, cause "they aint paid to". there are multiple tech tips on Identifix, ALLDATA, and MOD, yet people do not want to read and learn.
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  8. 06-08-2008, 04:49 PM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

    Quote Originally Posted by fc735 View Post
    i only use the mopar one, although the NAPA unit is a reboxed OEM part. NEVER use anything from AZ for electrical.





    this is a PWM controlled relay, they have a penchant for burning up the drivers if there is too much draw. its basically a solid state relay. will set a CEL and cause multiple other issues if you try to rig in a standard ISO relay.



    they fail for a reason:excessive current draw. every one that comes in and i diagnose as needing a fan relay gets a current ramping done of the fan, and almost every one of them has a fan that is going out drawing too much current.

    it is very common for them to need both a fan and the relay, and i have never had one come back for repeat failure. not only on the grand cherokees, but also on the caravans.

    it really bothers me that there are so many techs out there that do not bother to check the current draw of a circuit to determine why something failed, instead of blaming "inferior parts". and yes, most dealer techs do not even check the fan draw, cause "they aint paid to". there are multiple tech tips on Identifix, ALLDATA, and MOD, yet people do not want to read and learn.
    Yes, the CEL P1491 is how I know it is going out every time. The fan is cheap enough I think, I will order a new fan and install that in the next few weeks. Damn thing cost me $61.00 today, it was $35 last time I got it. I have had this Jeep for 2 years, and I have had to replace the relay 4 times, replace the radiator once, now the radiator has another slow leak in it. I tried some stop leak, will see how that works. Its like this car just wants to be constantly in a state of almost overheating.

  10. 06-08-2008, 08:57 PM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

    its a dodge....

  12. 06-08-2008, 10:32 PM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

    I have an 04 GC, and I haven't had any problems with it... lucky me I guess

  14. 06-08-2008, 10:43 PM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

    Quote Originally Posted by Ninja11 View Post
    its a dodge....
    there is nothing dodge on this vehicle aside from the SKIM module. the cooling fan relay, ECM (JTEC for this year), data bus, and IC are all Jeep specific.

    what does that have to do with the vehicles problems? all cars are pieces of shit, and have issues.


    Quote Originally Posted by Paul View Post
    Yes, the CEL P1491 is how I know it is going out every time. The fan is cheap enough I think, I will order a new fan and install that in the next few weeks. Damn thing cost me $61.00 today, it was $35 last time I got it. I have had this Jeep for 2 years, and I have had to replace the relay 4 times, replace the radiator once, now the radiator has another slow leak in it. I tried some stop leak, will see how that works. Its like this car just wants to be constantly in a state of almost overheating.
    sounds like you have a problem with radiators. i only install OEM radiators. may want to see if there is an 800-radiator in your area, and ask for an OEM replacement. it wont have Mopar on the box, but it should be a Nissin or Koyo, which were OEM's on those particular units.

    i learned a long time ago to install only good parts, shit causes problems later down the road.


    that being said, you dont have oil pressure dropping off when hot do you? i have had untold amounts of these things come in after overheating with a lower than normal oil pressure when hot, caused by cam bearings wearing or a crack in the head.

  16. 06-08-2008, 10:55 PM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

    Quote Originally Posted by fc735 View Post
    there is nothing dodge on this vehicle aside from the SKIM module. the cooling fan relay, ECM (JTEC for this year), data bus, and IC are all Jeep specific.

    what does that have to do with the vehicles problems? all cars are pieces of shit, and have issues.




    sounds like you have a problem with radiators. i only install OEM radiators. may want to see if there is an 800-radiator in your area, and ask for an OEM replacement. it wont have Mopar on the box, but it should be a Nissin or Koyo, which were OEM's on those particular units.

    i learned a long time ago to install only good parts, shit causes problems later down the road.


    that being said, you dont have oil pressure dropping off when hot do you? i have had untold amounts of these things come in after overheating with a lower than normal oil pressure when hot, caused by cam bearings wearing or a crack in the head.
    No, no oil pressure issues. I have never actually let it over heat. Moving air is usually enough to keep the engine cool if the relay goes bad, and I have always replaced it in a day or two. The notification system tells me if it is low on coolant when it is just low in the overflow tank, so it is never actually low in the radiator.

  18. 06-09-2008, 07:38 AM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

    FLIM-FLAM
    Finally someone who knows what hes talking about. I too have a problem with my relay circuit.after the third relay 2nd motor and second harness i put in a belt driven clutch fan. NO MORE OVERHEATING YEA!But it set off my cel p1491.I REPLACED THE RELAY Checked for 12v on pin 1 ok, checked ground ok, checked for signal from pcm no good checked cont. from pin 17 to relayy ok tried to clear code but cel stays lit how do I get rid of the code and light so i can pass mvd emissions test.It is my only transportation an d mvdisnt going to register it please help thank you, mike

  20. 05-31-2017, 06:28 AM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

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  22. 05-31-2017, 02:46 PM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

    Quote Originally Posted by Roxtar View Post
    9 years.
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  24. 05-31-2017, 10:00 PM
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    Re: 2003 Jeep Grand Cherokee Laredo - Tech question

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  26. 06-10-2017, 08:53 PM

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