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Author Topic: Grand Cherokee flashing MIL  (Read 1644 times)

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Andyp

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Grand Cherokee flashing MIL
« on: August 06, 2021, 12:19:22 PM »

So, on the way to work yesterday morning the MIL on my 2001 Grand Cherokee 4.7 flashed for around 6 seconds before going off again. As I was overtaking a lorry at the time I couldn't pull over. I did the key dance and just got "done" so as there were no other concerns I carried on. The light hasn't come on since, there doesn't seem to be a lack of power or any vibration and idle is smooth. When I got home yesterday the idle did jump to 1300 and drop back again after turning the climate control off. At the time the light started flashing I'd just come off WOT and running on LPG.

I've tried my code reader and pulled P0300, P0301 and P0303. I've cleared them to see if anything comes back. What are the thoughts on how soon I need to worry? If it hadn't been on LPG at the time I'd probably be worrying now but I'm wondering if it was temporarily running rich when I came off the throttle.
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Jonny Jeep

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Re: Grand Cherokee flashing MIL
« Reply #1 on: August 06, 2021, 07:58:40 PM »

A flashing MIL signifies a multiple misfire and is a prompt to stop driving before engine damage occurs.

Since you'd just come off WOT and were on gas maybe the fuel didn't cut off as it would have on petrol and the changed spark timing/momentarily incorrect fuelling caused the misfire. If it doesn't recur, I don't think I'd worry about it.
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Andyp

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Re: Grand Cherokee flashing MIL
« Reply #2 on: August 06, 2021, 09:04:48 PM »

That's what I was thinking (hoping?) myself. Now I've cleared the codes I was thinking of going for a drive on petrol to see if any codes reappear.
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Andyp

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Re: Grand Cherokee flashing MIL
« Reply #3 on: August 22, 2021, 01:02:33 PM »

I've driven it a few times now and no MIL or stored codes. However, after a drive of around 20 miles or driving in traffic the idles jumps when put into P or N. In D it stays at 700 but in P or N it jumps straight to 1100 before dropping to 900. When cold it's fine so I assume heat build up in the engine bay is having an effect. I've checked vacuum hoses and removed the IAC valve (which moves when the ignition is turned on so I assume is OK). I've probed the TPS and got 0.55v closed rising to 3.75v at WOT, I tried again straight after a run when the idle went up and got 0.62v to 3.75v. As the reading increased hot I'm thinking of swapping the TPS and cleaning the throttle body. My local dealer wants 150+VAT so I looked online and this is where the confusion starts. The part number on my sensor is 56027940 (this sensor came off my previous 2001 as the vehicle had a constant high idle when I got it), Rock Auto show no Mopar part available for my year. On the aftermarket sensors and a lot of US sites this number seems interchangeable with 5017479aa which Rock Auto do list at just under £100 delivered. I can find NGK/NTK and Denso for around £40 as well. Is it worth sticking with Mopar? What are the chances that the more readily available part number is interchangeable?
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Brynjaminjones

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Re: Grand Cherokee flashing MIL
« Reply #4 on: August 23, 2021, 01:54:45 PM »

I would always try to stick to Mopar when replacing sensors. I know of several people that have had problems with aftermarket ones.


You haven't by any chance got the engine bay wet recently have you?
I had an intermittent high idle after hosing down the engine bay of my XJ recently.
It would come and go for months, and I eventually realised it was the TPS.

Putting it in the oven at about 110 degrees Celsius for several hours finally fixed it!
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Andyp

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Re: Grand Cherokee flashing MIL
« Reply #5 on: August 24, 2021, 05:55:13 AM »

I can't remember it having got any wetter than normal. No flooded roads or fords, the odd big puddle but that's reasonably regular.
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carljh

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Re: Grand Cherokee flashing MIL
« Reply #6 on: August 27, 2021, 01:04:52 AM »

I've both the 2001 and 2004 parts list, the 2001 TPS part # is 4882219 and the 2004 it's 5017479AA, when you search for the 2001 #
, sites like Moparpartsgiant.com say its replaced by the 2004 #.
the part # you gave comes up as a Dodge Durango/ram part, probably still the same part but easier to match using the Jeep part numbers.
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Andyp

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Re: Grand Cherokee flashing MIL
« Reply #7 on: September 05, 2021, 05:40:24 PM »

Thank you, that's what I was starting to think but with no 3vidence. I ordered the TPS from Rock Auto (and an IAC while I was ordering). Both now fitted and the throttle body cleaned, all seems good from the initial test drive.

Imagine my surprise when the part number engraved on the new TPS wasn't 5017479AA, as on the box, but 56027940 again!

Are the parts lists you have electronic?
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carljh

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Re: Grand Cherokee flashing MIL
« Reply #8 on: September 07, 2021, 01:28:29 AM »

yes pdf files, along with the full FSM, the 2001 parts list has RHD export parts listed, where as the 2004 one is just LHD, so nothing for the 2.7 CRD, it probably exists but I went from 3.1TD to 4.7HO so didn't look for it.
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Andyp

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Re: Grand Cherokee flashing MIL
« Reply #9 on: October 23, 2021, 06:55:33 PM »

Could I be cheeky?
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Jonny Jeep

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Re: Grand Cherokee flashing MIL
« Reply #10 on: October 24, 2021, 12:38:57 PM »

Here's the 01 and 04 WJ/WG parts lists...
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