charging problem with 93 dodge spirit - voltage regulator?

93 dodge spirit 220K miles

My Check engine light came on and the voltage indicator looked low
(10-12V). Fault codes wer 12, 17 (fixed by replacing thermostat), and
41. Checked the alternator (it was bad), replaced it and took a test
drive. So far so good.

The next day , the check engine light came back on and the charge
dropped back to 11. Pulled the alternator back out and had it checked
(it was good). Replaced the alternator belt. Problem went away.
Three miles down the road, the problem returned (I checked the belt
tension when I got to work and it seemed OK)

Next step - voltage regulator?
The consensus seems to be that the voltage regualtor lives in the
computer, but how do I verify (the Bosch replacement alternator didn't
have a sticker on it labeling it as externally regulated). Also, the
alternator has 5 connections (3 large posts and 2 small). I assume the
large posts are B+ and field connections? What are the 2 small posts?

Thanks for any help - I'll be the first to admit I don't really know
what I'm doing.

wrote:
> 93 dodge spirit 220K miles
>
> My Check engine light came on and the voltage indicator looked low
> (10-12V). Fault codes wer 12, 17 (fixed by replacing thermostat), and
> 41. Checked the alternator (it was bad), replaced it and took a test
> drive. So far so good.
>
> The next day , the check engine light came back on and the charge
> dropped back to 11. Pulled the alternator back out and had it checked
> (it was good). Replaced the alternator belt. Problem went away.
> Three miles down the road, the problem returned (I checked the belt
> tension when I got to work and it seemed OK)
>
> Next step - voltage regulator?
> The consensus seems to be that the voltage regualtor lives in the
> computer, but how do I verify (the Bosch replacement alternator didn't
> have a sticker on it labeling it as externally regulated). Also, the
> alternator has 5 connections (3 large posts and 2 small). I assume the
> large posts are B+ and field connections? What are the 2 small posts?
>
> Thanks for any help - I'll be the first to admit I don't really know
> what I'm doing.

If the computer-integrated regulator is bad, it will set a code. It may
even be the 41 that you got.

If the regulator is bad, the problem can be fixed by installing an
external regulator. Dan Stern posted the procedure in this NG just last
week. A search of this NG should find it.

-Kirk Matheson

On Wed, 8 Feb 2006, wrote:

> If the computer-integrated regulator is bad, it will set a code. It may
> even be the 41 that you got.

Yep, it'll be the 41 he got.

> If the regulator is bad, the problem can be fixed by installing an
> external regulator. Dan Stern posted the procedure in this NG just last
> week. A search of this NG should find it.

I keep that text on "speed dial".

On 8 Feb 2006 11:03:50 -0800, wrote:

>Thanks for any help - I'll be the first to admit I don't really know
>what I'm doing.

One thing to check is the battery connections. They can cause a lot
of weird problems when the connection isn't quite good enough. A lot
of the problems they cause don't make sense, and it's very hard to
figure out how a battery connection could cause such problems.

One way to check the connection is to turn on the headlights and
measure the voltage between the battery post and the cable terminal
which is attached to that post. That voltage should be zero. If you
can measure even a fraction of a volt, the connection is bad.

When my battery connections were bad, I fixed them by cleaning the
insides of the cable terminals, where they wrap around the posts, with
fine sandpaper, and replacing the bolts that tighten the terminals,
because those bolts were ruined by age and corrosion.

>
> One way to check the connection is to turn on the headlights and
> measure the voltage between the battery post and the cable terminal
> which is attached to that post. That voltage should be zero. If you
> can measure even a fraction of a volt, the connection is bad.
>
The voltage between post and terminal is 0.000 Volts. Voltage between
+Post and B+ is 0.035V with headlights on. I know there should be some
potential drop across the wire to the B+ terminal, but how much?

Also, the harness that attaches to the alternator has 5 leads, the wo
smallest attach out of a black plastic 3"x2" cartridge looking thing.
Anybody know what purpose this serves?

Thanks,
Frank

Found D. Stern's post, which also explained the two small studs.
Off we go.

Sorry for the string of posts.
After some poking around with a voltmeter and reading D. Stern's post
several times, I've identified the two field terminals, and have two
ground studs handy on the alternator itself.

(sheepishly): Does the connection between (new) regulator base and
battery neg need to go all the way back to the battery, or can I use
one of the ground studs on the alternator?

Thanks for all the help,
Frank

On Wed, 8 Feb 2006, wrote:

> 93 dodge spirit 220K miles
> Next step - voltage regulator?

Yep, next step voltage regulator. I post the facts and fix on this
issue about once a month.

> The consensus seems to be that the voltage
> regualtor lives in the computer

Correct, the voltage regulator is in the SBEC (Single Board Engine
Controller).

> alternator has 5 connections (3 large posts and 2 small).
> I assume the large posts are B+ and field connections?

Nope, the shielded large one is B+ and the unshielded one is case
ground. The two small ones are fields.

This voltage regulation issue is the most common SMEC/SBEC failure
(which is not to say it's very common; Chrysler's modules tend to be
pretty durable-just that this particular failure is usually how they
fail.) The official fix is to replace the SMEC/SBEC.

Here is a much less costly fix that *will* work, without replacing the
engine computer and without causing any additional problems:

First, pick one of the following regulators:

Regular normal electromechanical regulator:
NAPA Echlin VR32

Extra heavy duty electromechanical regulator w/vibrationproof mount:
NAPA Echlin VR34

Extra heavy duty electromechanical regulator w/vibrationproof mount and
convenient external voltage adjustment screw:
NAPA Echlin VR35, Standard-Bluestreak VR106

Transistorized regulator with no moving parts (no adjusting screw):
Standard-Bluestreak VR101, Wells VR706 (the wells item is very
inexpensive; it works but Wells doesn't make my favourite stuff)

Waterproof potted IC regulator with no moving parts (no adjusting
screw):
NAPA Echlin VR1001, Standard-Bluestreak VR128

Any of these regulators will have two terminals on it, one marked "IGN"
and the other marked "FLD". (the VR1001 and VR128 have the "fld"
terminal on the end of a short wire lead). The alternator gets the
original field wires removed from its two field terminals (right next
to each other, small studs with nuts retaining the two flag terminals
-- be careful not to break off the studs!).

The regulator IGN terminal gets 12V via the ignition switch, and the
"FLD" terminal gets connected via a wire to one (either) of the field
terminal studs on the alternator. The other field terminal on the
alternator gets connected via a wire to ground. Run a ground
wire-16ga is plenty-between the regulator base and the battery
negative terminal, and mount the regulator such that it won't rock 'n'
roll around. At this point, your charging system will once again work
fine. If you got the adjustable regulator, set it for 14.2v across the
battery with the engine fully warmed up and idling, no lamps or other
accessories on, and ambient temperature above 50°F.

Your "Check Engine" light will probably come on in response to this
fix, because the SBEC does not see itself as able to control the
voltage (right, it can't, because that's now the job of the new
regulator you just finished installing!) To silence the spurious
warning, put a resistor across the two original field wires that you
removed from the alternator, before securing these wires such that they
can't ground out or get caught in any moving parts.

Close the hood; you're done.

DS

On Thu, 8 Feb 2006, NoNick wrote:

> Does the connection between (new) regulator base and battery neg need to
> go all the way back to the battery, or can I use one of the ground studs
> on the alternator?

Ground stud on alternator is fine.

Hmm. Connected the new voltage regulator, and the charge to the
battery is still low.
Here's what I did:
1. Mounted the new regulator to one of the ignition coil mounting
screws, which made both a secure mount and a good ground (I checked the
resistance).
2. I connected the wire formerly connected to the top field post to the
IGN stud (this is the same wire with 11.5 V when the car is running)
3. connected the FLD stud on the voltage regulator to the bottom field
post of the alternator.
4. Left the B+ wire connected to the large shielded connector on the
alternator
5. Connected the other field post and the 4th wire in the harness to
one of the bolts in the body of the alternator (the 4th wire was
formerly connected to the alternaotr body).
6. Reconnected the battery neg post and started the car.
I have not connected the resistor yet between the wires formerly
connected tot he filed posts, but from the previouis posts, it seems
like this would only affect the check engine light, not the actual
charge to the battery, yes?

Anything I'm doing worng?