Chrysler Repair: 93 Acclaim - Erratic Charging, Code 41; rear axle creaks, gauge needle, glaring defect

Question
Hi there!

I have a 2.5L 1993 Plymouth Acclaim in pretty good shape, but my-oh-my does it have one glaring defect!  When I start it, it starts right up... but the battery amp dash gauge needle will oftentimes not move from battery voltage to a charging state.  When it does this, all the lights and fans remain dim/slow, the CHECK ENGINE light comes on (code 41), and the battery is obviously discharging.  Sometimes, revving the engine a couple times will do the trick, and the ammeter will all of a sudden pop over to "charging", the lights will brighten up, and everything will seem alright.  I've replaced the computer, alternator, battery, ASD relay, and done several quick visual checks of the wiring -- although I must admit, there's so much of it, I'm beyond overwhelmed.

There was a hint of this problem before (and it still does this if I luck up and the car starts charging in the first place).  The amp gauge would show a proper charging state at speed, but if the car came to a stop and idled in drive (especially with the lights on and the heat on high), the needle would creep down toward a discharging state.  The lights will eventually begin to dim and the fan slow down.  Simply popping it in park or neutral and holding the engine at 1000rpm or so would bring the needle back to the "proper" charging state, but only as long as I kept the revs above idle.  You can imagine the looks I've gotten at the stop light revving the little 2.5L!  Folks are clearly amazed that I'd apparently want to race them... lol....

I know it must be something relatively simple, but my generic wiring diagrams are driving me nuts and I can't figure this one out.  And I'm having zero luck finding a factory service manual for this thing.  Thankfully, everything else on the car is in pretty good working order.  There *is* a weird issue with the driver's side of the rear axle making a bizarre metallic chirping/creaking sound when hitting bumps, and changing the shocks did nothing to change this.  But otherwise, it's in pretty good shape.

OH!  A little history on the car -- the previous owner had a shop replace a defective ignition switch that had mysteriously become very hot to the touch.  I actually have the original switch, and one of the terminals is scorched.  The original owner thinks the second charging issue may have begun happening when she received the car back from the shop.

Thanks in advance for any help you can provide!

Answer
Hi Tre,
The 41 code says there is something wrong with the field coil circuit of the alternator. The wire is dark green and comes from pin 20 of the 60-way at the PCM and of course goes to the alternator, and it passes thru one 10-pin disconnect behind the battery in getting there. Otherwise there are no other splices. So I would check the continuity of that wire and try shaking the harness to see if there might be a crack/open connection in the wire somewhere along that path. The other end of the field coil is attached to the + post of the spark coil via a dark green/orange wire, to check the continuity of that wire too. It carries 12V from the ASD relay and that relay is OK by the fact that the engine keeps running even though the alternator acts up. It is either one or the other wire or I suspect your alternator has a poor field coil that is not "solid" and reliable. Such an intermittent loss of conductivity would do exactly what is happening to you.
On the rear axle noise, that is a weak weld on the round tube that is hidden in the rear axle (inverted U-shape). At one end or the other that tube has begun to crack a weld between it and the plate to which the spindle for the wheel is attached. Listen carefully as you push down on each rear corner to see which side is making the noise. Though it may sound like it's on the driver's side, the actual crack may be the other side. Then go to a welding shop and have them spot weld the tube to spindle plate connection once again. They should be able to go about half way around and that will either quiet or silence the noise. The tube is called a "torque tube" and even if it breaks free it won't be a hazard, but do get it re-welded as best as possible. Should cost about the minimum welding charge which is usually about $25. It is common on this re-axle design.
Let me know how this works out.
Roland
PS Please rate my answer, thanks.