Do I need to get a replacement PCM flashed and VIN programmed?

Jones

Jones

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Joined
Oct 6, 2018
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32
Location
Tyler Texas
My battery was showing low on the voltmeter after driving a while. I would recharge the battery and drive for half an hour and it would shoot back to about 9 again.
I got the battery tested at O’Reillys and they said the battery was fine but the computer they used said that the volt regulator was bad which is located inside the PCM. I need to get a new PCM but I what I need to know is: Do I need to PCM flashed and vin programmed for a 1998 Wrangler Sport 5 speed?
I appreciate the help. I know that 1997 models don’t need to be flashed and vin programmed so I figured it wouldn’t be any different for the 1998. Thank y’all for the support.
need to know ASAP as I’m a poor college kid with a TJ as a daily driver. Trying to buy a PCM ASAP.
 
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I wouldn’t trust O’Reillys to diagnose a PCM failure. Check your wiring harness before going any further.
 
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The voltage regulator is indeed inside the PCM but it’s pretty rare that it fails.

Perform a visual inspection of the wiring harness loom from the alternator to the PCM. My ‘05 may be different, but the wiring should run over the oil dipstick bracket, to the passenger side of the block then up to the valve cover and over to the PCM. If you find that the plastic loom is rubbing, open it up and inspect the wires.
 
AjRagno said:
The voltage regulator is indeed inside the PCM but it’s pretty rare that it fails.

Perform a visual inspection of the wiring harness loom from the alternator to the PCM. My ‘05 may be different, but the wiring should run over the oil dipstick bracket, to the passenger side of the block then up to the valve cover and over to the PCM. If you find that the plastic loom is rubbing, open it up and inspect the wires.
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Checked it out. All seemed to be fine. Appreciate the suggestion. I will do some further inspecting tomorrow in the day light and when I regain energy haha. Thank you very much
 
I have swapped around PCMs on my '98 with zero issues. I was told it would run but throw a code which was fine for me since I was just trouble shooting (turned out to be a harness issue) but to my pleasant surprise no code ever. YMMV.
 
Sorry for the delay @Jones @Chris.

How old is your battery? Jeeps are very temperamental on voltage and my technician recommends changing out if over a year.

Is your Jesp Federal or low emissions? Any codes present?
 
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