TJ low voltage issue ‘check gauges’ alert stays on (P0700 & P0613)

[White Shadow 99]

I have a 06 Jeep Wrangler Unlimited auto it recently started saying ‘check gauges’ on the dash but would clear with restart of the engine, Only happened at quick turns or sudden stops so assumed it was windshield fluid sensor.

Then the jeep wouldn’t start on the trail (click click click) so I disconnected the battery and reconnected and it started but had low voltage (9 volts). Drove it tell it died, had to I was 5 miles in on a aggressive trail. Replaced the alternator died after a minute so replaced battery too. Drove off trail but voltage was not consistently at 14 volts, more around 12.5 volts and ‘check gauges’ was back on then also got check engine light.

Got it home and scanned it with OBDII. Got P0700 and P0613. Cleared all and ran fine with 14-15 volts at idle. Went back out on the trail and got the ‘check gauges’ again and the voltage was back down to 12.5 volts. Then check engine light was back on too, so I scanned again and both codes came back up. Now disconnected the battery for 10+ hours to fully clear memory. Started it up and ‘check gauges’ came on immediately and still only the voltage at about 12.5 based on the battery so alternator is not providing power.

OBDII scan showed nothing again. Already cleaned the battery terminals with a wire brush. Did a second overnight for disconnect of 10+ hours. Also disconnected the four plugs to the computer and there’s a lot of electronic gel in there so I clean that out with a toothbrush. I read on this forum else where that replacing the PCM fixed things but It would need to be reprogrammed with the Vin and mileage seems to be two people on eBay that can do this. Any other wisdom, suggestions or success stories for this type of issue?

If I think back to the timing of when this started the only thing I can think of electrical was installing LED headlights and LED fog lights. Both no-name brand off Amazon, fog lights wired to stock wiring (two wire connection) and headlights same stock three prong connector but I did not use the anti-flicker pigtail as I thought that was only an issue on JKs. Although I don’t see how the lights can affect the computer or the alternator not to operate properly. Issue does not show any consistency with lights on or off


Thanks Dan

 

[Chris]

P0700 and P0613 usually implies something is going on with your TCM (transmission control module). That's certainly not unheard of with a vehicle this age. Heck, I hear about it fairly often the older the things get. So those transmission codes haven't come back and there haven't been any other codes since then?

Your LED headlights and fog lights would have nothing to do with this, that's a guarantee. The anti-flicker harness isn't necessary on TJs, only on JKs since they have a CANBUS system that requires it.

What your issue may be is the voltage regulator. Unfortunately, on TJs the voltage regulator is built into the ECM, so you'd have to replace your entire ECM to fix it.

In 2005 the TCM was integrated to the ECM (on 04 and earlier they are separate). So guess what? Every single thing you're describing is starting to sound like your ECM / TCM (which are one unit) are going bad and unable to regulate voltage.

 

[White Shadow 99]

Yes the problem is occurring before the two transmission codes it’s the fact that the computer is not allowing the alternator to charge the battery the codes not happen until it draws the battery low enough to trigger those two codes otherwise the transmission works fine. One of the companies on eBay that reprograms or fixes the ECU/PCM says it could be the two wire connection going to the alternator has anybody else heard of that?

 

[Chris]

Never heard of a two wire connection going to the alternator, but it's worth looking into. Try that, and if it's not the solution, then you my friend need a new ECM. Not unheard of at all, lots of us have had to replace our ECM.

 

[White Shadow 99]

There is a large gauge wire from battery to alternator, of course. As well as a two wire plastic connection that must go to the PCM for voltage regulation. So now I am assuming PCM or wires from PCM to Alt. Unfortunately can’t test the wires or connection for a week, had to leave it in Tahoe. But I did pull the PCM, battery and alternator for testing.

 

[Head Lice]

Never heard of a two wire connection going to the alternator, but it's worth looking into ....

Pull the connectors from the back of the alternator ...... check for corrosion. This is an old Dodge/Cummins fix. May be your problem also.

 

[Chris]

Hopefully it's just the wires and not the PCM. Though I won't be surprised if it is the PCM, it seems to happen from time to time.

 

[bobthetj03]

Could possibly be a defective alternator. Have you tried testing voltage from the battery with a meter?

 

[White Shadow 99]

Hey guys here’s the verdict battery was fine alternator was fine all grounds were fine PCM was fine. It was actually a faulty positive battery terminal that was not getting good connection it was actually half broken and rusted underneath where the crimp is so it wasn’t making a good connection but not visible from the top. Good thing I checked all the simple things first before dropping $1500 on new computer or should I say refurbished thanks guys

 

[Chris]

It just goes to show that it is almost always the simplest solution. That’s what I find most of the time. This doesn’t surprise me actually. With the age of our TJs, everyone should be replacing their battery terminals just as a form of preventative maintenance.

Glad you got it sorted out, and thanks for the update. It’s alwahs helpful for people who might stumble upon this thread in the future.

 

[Jerry Bransford]

Hey guys here’s the verdict battery was fine alternator was fine all grounds were fine PCM was fine. It was actually a faulty positive battery terminal that was not getting good connection

Nice that you found that. 99% of the time your symptom is caused by nothing but a loose/corroded/dirty/bad battery connection. I wish I had a $1 for every time I've recommended removing the connectors, wire brushing them and the battery posts, cleaning, and tightening the connectors to fix problems like that. That's what I was going to suggest here until I got to the post where you had done just that. Nice job finding the problem!