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Posted on Jul 26, 2008
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MY 1998 RAM 2500 (5.9 DIESEL) ENGINE RPM FLUCTUATES AT 45 MPH TO 55 MPH WHEN IN OVERDRIVE, LIKE IT IS SHIFTING FROM OVERDRIVE TO DRIVE AND THEN BACK TO OVERDRIVE. IT ALSO FLUCTUATES WITH O/D OFF AROUND 35 MPH. I HAVE REPLACED THE TPS WITH A NEW ONE ALREADY AND THE PROBLEM STILL EXISTS.

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  • Anonymous Nov 21, 2008

    Mine is a 95, but the OD symptoms are exactly the same. I have been all through the harness, and have scanned it several times.

  • grahamdav22 Apr 27, 2009

    Mine's a 1999 diesel. The RPM fluctuates at 45 to almost 60 mph.

  • jtandrsn May 02, 2009

    my 06 5.9 cummins runs at 1500 rpm @ 55 mph, sometimes 1300 rpm, sometimes as low as 1100 rpm, this is not consistant and I dont notice any unusual shifting or power loss

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  • Posted on Aug 07, 2008
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I had same problem. A govenor relay had to be changed in the transmission.

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The problem is caused by electrical noise making the torque convertor go in and out of lock up. The dodge dealer has a computer flash for it. The fash only works about 30% of the time. This is a major problem to diag. Usually requires ground straps installed on pcm or pcm replacement could also be the altenator, wiring, or anything that runs to the pcm or tranny.

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  • Posted on Jul 26, 2008
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Check your gearbox oil level if it is fine it maybe that your gearbox sensor is failing and needs replaceing or not earthing out properly.check these and if still plays up leave message for me try to help you more

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