I've been lurking, finding greatly helpful info from this site for quite some time now. I finally figured it's time to join and both get help, and hopefully offer help from the many projects I've already completed.

I have an 03, 3.9L Dakota, RWD with 190,000 miles that went goofy on me this week. I'm in Michigan, where the temperature was floating somewhere around 18 degrees when everything really started to act up.

First, I had a bit of a sputter and a small backfire. Before I had a chance to replace plugs or wires, I was driving on the freeway and suddenly lost all consistency. I could barely get the truck back up above 60MPH and the RPM's were jumping between 1500 and 4000, while staying consistent on the gas. The engine revving almost acted like I was slipping on ice, though I wasn't.

I ended up taking it to a shop, where I got a long list of overall problems (sway bar links, brake lines, trans pan, shaft seal leak, pinion seal etc etc). Anyway, it also included fault codes P01391 and P0305. Mechanic suggested changing out the plug wires, but since there was so many minor repairs, he also didn't think it would be worth having him throwing more of my money at the truck. I figured I could get it home (40 miles away), change out the wires and start working on the laundry list of other fixes.

In driving it home, I regained consistency (aside from the occasional backfire while accelerating between 50 and 60MPH and could maintain a normal 75MPH. I made it about 30 miles before I quickly and suddenly lost all power. The check gauges light came on and the battery voltage dropped to nothing. Then the radio went out, all other dash lights came on (temp, airbag, seatbelt and everything else), and I luckily coasted to a stop at a rest area.

The mechanic mentioned the voltage drop occurred during his test drive, but in testing the battery and alternator, both checked out fine (which isn't suprising since both were replaced within the past 6 months). If I shut the truck off and let it sit for a few minutes, it will start back up and run for about 2-3 minutes, before quickly losing all voltage and dying.

From what I've tracked down (from the mechanic suggestions, my brother another Dakota owner, and reading this forum), I've been told this could be from a bad camshaft position sensor, or worn plug wires that could be shorting out.

Any ideas what would cause those two fault codes, combined with the complete loss of power? I'll be working outside, in 10-20 degree weather, so the less guessing and checking I have to do the better.

 

Hi and welcome to the forum.

P0305 is a misfire on cylinder #5.
P1391 is a loss of the cam or crank position sensor.

As you've found, Dakota's don't like low voltage. The question is, what is happening first? The low voltage, which can cause the above symptoms, or is the low voltage a result of the engine dying?

It wouldn't hurt to pull the plug on #5 and give it a look. When was your last full tuneup? Plugs, wires, cap, and rotor?

The cam sensor is an easy enough swap. The crank sensor is a bit more complicated.

FYI, you can check the codes yourself. Beginning with the key off, turn it to run (not start), then off, run, off, and leave it in run. Any codes will display in the odometer window.

 

Thanks for the quick reply.

The symptoms have gone:
Sputter/Backfire.
Low Voltage.
Dying.

Plugs, wires, cap and rotor were all changed approximately a year ago.

O2 sensors and Fuel injectors have been on there since I purchased it, which was 7 years ago.

 

When you say losing all voltage, is it that the alternator stops charging, or that everything acts like it has been shut off and turned back on? If the alternator stops charging (volts go from 13.5+ to 11.75- ) then it could be as simple as the battery temp sensor or something on the alternator (new != reconditioned/rebuilt != quality). If everything is cutting out, I'd look more towards the PCM or the cam signal.

If the PCM loses track of the cam/fuel sync, then it could portentially change the timing of the fuel injectors and/or ignition timing (although the ign timing is more crank sensor based i would think). Which would cause the misfire.

 

The check gauges light came on, and thevoltage/battery gauge on the dashboard dropped from about mid-range to absolutely nothing. At first, I stopped to see what was shutting down, if anything, and found everything was still running normal. No light dimming, no radio cutting off.

When I started the truck back up, the battery gauge jumped back to it's normal level, then dropped to nothing again after a few minutes. This was on Tuesday night originally.

I drove it about 5 miles to a shop and left it for testing. Check gauges light was on, voltage gauge showed nothing on the dash, but no apparently loss of power.

The shop gave me the diagnosis mentioned in the first post (with the fault codes) and told me the battery and alternator tested fine, but they found the same reaction during a test drive. Battery gauge on the dash dropping out with no noticeable problems other than the check gauges light coming on.

So, today, I decided to drive it home to further work on it. The check gauges light came on for about 5 miles, then went away. About 20 miles in, the check gauges light came back on, and again the voltage gauge on the dash dropped to nothing. About 5 miles later, all electrical power drained as I was coasting into a rest area. After sitting for a few, it would start back up and then lose all power and shut off again within 2-3 minutes.

I couldn't get it to keep electrical power long enough to feel comfortable driving it any further.

 

Don't rely on the dash gauge, hook up a gauge in the cab that you can see. Just wire a meter into the cigar lighter or something.

The next time you get a CEL, pull the codes then and there.

The PCM is in the voltage regulator. You should throw codes for the alternator low output, P0562 would be low, P0563 would be high, and P0622 would be the field not switching properly. P1478 is battery temp sensor volts out of limits.

 

If I remember correctly a bad battery cell will do this from a cold start it will be ok but then cut out as the battery cell warms up and can be intermittent.

Testing will not show anything wrong every time

 

you mean the voltage regulator is in the PCM.

Like Dan says, take a multimeter and put it in the cig lighter or somewhere you can easily grab power without shorting anything out. 11 volts is about where our trucks get moody- I've started as low as 10.5, it did not run worth a damn.

 

Great help so far. I'll let you know how it goes.

Wondering some more personal opinions. I've had the Dakota for 7 years and gotten about 160,000 miles out of it. In the past two years, I've replaced all four tires, battery, alternator, upper/lower ball joints, inner/outer tie rods with an alignment, u joints, pads, rotors and calipers on the right side (last weekend, got busy before I could finish the right), plugs, wires, distributor and rotor, radiator hoses.

When the truck went haywire, I had a shop do a full once over inspection, knowing I still have a lot of things to take care of.

The list was pretty long and without giving a quote, the shop told me I'd likely be over $3,000 in repairs. KBB puts the truck worth just about $3,000 in fair condition. I'm a fair do-it-yourselfer, but I also do accounting work, so I'll be working 60-70+ hours a week January through April.

Do you guys think it would be worth replacing the following to keep the truck going, or is it time to call it quits on this old guy?

Here's what the shop listed as problems, and I don't doubt any of it:
Exhaust behind converter
Replace right upper and lower ball joints...again (I'd hope they'd be warrantied, but have to check)
Two front tires (damn crappy ball joints)
Left rotors, pads and calipers (have the parts already)
Pinion seal
Trans pan and tail shaft leak.
Brake lines from below master cylinder to back.
Rear sway bar links and bushings.
Trans fluid flush.
Coolant leak.

Most of it isn't too frightening, the worst of it being listening to the wife complain about the money I'm dumping into it. Not sure how big of an issue the trans pan and tail shaft leak could become, or if those are DIY projects.

Not sure I have the patience to do the brake lines and muffler myself and those seem to be a bit on the higher side in a shop.

So, what do you guys think? Is it worth the money or time for retirement?

 

it depends greatly on 1) where you live, 2) how much fictitious crap the shop made up, 3) what brand of stuff you used in the previous repairs.

The sway bars aren't really maintenance items. They just kinda sit there. I wouldnt worry about them.

Trans fluid flush should be done every 50,000 miles

Exhaust, if you live in a salty area, it might be rusted...but I wouldn't worry on it a whole lot.

If you didn't use Moog ball joints, i could see them being worn out. If you did, I call BS.

Trans pan leak is probably just a poorly installed gasket.

The tailshaft and pinion seal leaks are the only major things I see there.