[crash70rs]

Its not a Rod, just my girls daily driver. Its done this forever and its really got me stumpped.

93 dodge spirit, 2.5L auto.

When you turn off the ignition switch the car keeps running. Most of the time it runs crappy in this situation with the dash lights flashing. It will shut off when the electrical system is overloaded but turning on headlights, brake light etc..

It has a new alternator (I've seen this problem with bad altenators before). I tested the feild coil leads on the altenator, they seem to act as they should with the ignition switch on and off without the car running. One wire get batt. voltage and the other get less about 7-9Vdc. with the switch off they both get 0. This is also true while the car is running, but when the ignition is turned off the field coils are still getting power

It seems like there some kind of electrrical feedback keeping it on. Is there a relay associated with the ignition switch? I would imagine so but was unable to find anything in the schematics.

I'm pretty stummped on this one.. any help would be great.

(btw just rebuilt the 2.5l and it running great!)

Thanks!

[tomthecomic]

This might help and it is cheep. I think you are getting alt feedback though the trouble light. You need to put a diode (radioshack) from the alt to warning light. It is a brown wire on GM, yours could be different. I don't know the size or the dioed. Go to Mallory web look under tech and knowledge bass search diode. I think this is the problem.

[Bryan59EC]

I once had the electric fans on my 79 Chev C-10 keep the engine running
Put a diode inline and it stopped

Also, same truck-----an electric choke kit from NAPA did the same thing

Bryan

[docvette]

Doc here,

Here is the charging system for that vehicle:



The BLK/TAN SHOULD have 12 volts on it at all times...IF this line is low, I'd suspect two things..The Fuse link is OPEN..AND the Diode pack has one or more Diodes reverse Biased (leaking backward) OR crowbared together..a rebuild/replacement will be in order.

The Dark Green/Orange wire goes to the Ignition coil AND pin The auto shut down relay normally open contact..Then on to pin 57 of the ECU..IT should only have power with the key on. It's state "may" vary from 5.5 volts to 12.5 volts BUT I'd suspect this will be 12 volts..AND this would cause intermittent running If you had some shorting rectifier diodes.

The Dark Green goes to Pin 20 of the ECU..Voltage unknown..maybe 5.5 to 12 .5 Volts you'd need a pinout of voltages for the ECU to be sure..and may cause dropouts and flashing.

BLACK is hard , properly bonded ground .. Without this , it will cause all kinds of problems..

Pull the alternator and have it tested..Sounds like the rectifier/Regulator diodes are headed south..

Doc

[crash70rs]

Thanks for the responses. I've done the diode fix on some GM cars in the past. But this is a new alternator.. just days old and has had no effect on the problem.

I will investigate the Auto shut down relay when I get home tonight.


The image of the schematic did not show up, maybe its the computer im using.

[docvette]

Originally Posted by crash70rs

Thanks for the responses. I've done the diode fix on some GM cars in the past. But this is a new alternator.. just days old and has had no effect on the problem.

I will investigate the Auto shut down relay when I get home tonight.


The image of the schematic did not show up, maybe its the computer im using.

Doc here,

IF I had a buck for every time I'd heard that..

BECAUSE it is new..does not mean it works..IN FACT , chances are BETTER that is bad than it is good..high fail rates!

Need to check that link first..

Schematic shows up OK here..must be your browser settings.

Doc

[crash70rs]

Yea.. that is a good point doc. I should know that since it happens to me ALL the time. Is there a way to check that? If one of the diodes did drop will the alt. produce the correct voltage still?

I checked the ASD realy last night, replaced it with a "new" one.. no effect.
when the car is running "off" this relay clicks off/on like crazy.

Later I plan on checking the direction of current flow in the coil of the relay to see if something is back feeding (which I don't think will be the case since its connected to the ECU).

Then maybe the same thing on the field coils on the ALT? see if they are sending a feedback signal in the opposite direction.

After those then maybe some extra gounds to make sure everything is good, then mess with the ignition switch some.

Thank you all for the responses

[crash70rs]

I did some pokin and prodin and found some curious things.

1. there is a code 41 being sent. which is "Alternator field control circuit open or shorted"

2. With the field wires disconnected from the alternator and the harness unplugged from the rest of the world (except for grounds and 12v to the alt.) There is a voltage potential between each of those wires and Positive batt. Which leads me to suspect a bad harness?

There is a molded connector the connects to the alt. containing the field coils ground and batt.

I have access to a parts car.. I see if I get get the harness from it to try.

In the mean time.. Im pretty lost and Thinking way too far into this than I should.. So please give me a reality check if digging in too much

[T-bucket23]

if you unplug the Alt does it shut off, this would be a simple test and would rule out the alternator. If this is a fresh engine swap did it do it prior to the swap. Chryslers are famous for using dulicate connectors under the hood. Something could be plugged in wrong.
I find it highly unlikely you have 2 alternators with exactly the same weird problem.
I would also check your engine grounds as something could be backfeeding if you have a weak or missing ground.

[crash70rs]

I try running with out the alt. to see if it shuts off (I pretty confident it will).
If the disconnect the field coil while its running (with the ign. off) it will shut down.

All the grounds look healthy, but I will take a closer look.

Unfourtunatly the parts car mentioned took a trip to the bone yard.

I think I may try to eliminate that section of the harness to the alt. and see how that works.

[docvette]

Doc here,

Check to be sure the alternator is wired on the CORRECT side of the ASD Relay..The NORMALLY OPEN side..This will be the Dark Green / Orange wire..AND be sure the ASD Relay is IN FACT operating..

IF you keep pulling the plug on the alternator you'll likely destroy the computer..IF you haven't yet..

The Dark Green / Orange, AND the Dark Green From the Alternator are DIRECT Feeds from the Alternator to Pins 57 and 21 Of the computer..If in fact you were seeing these Very high voltages you spoke of before...30 and 60 Volts, and they were correctly measured, and accurate, the chances are the Quad Driver inside the computer has gone fishing..

Seeing as you are now pulling codes that state "Alternator field control circuit open or shorted" Chances are pretty good that , that is EXACTLY what happened. Those I/O's are only low voltage reference.. (like +/- 5 volts), not hard ground, Not 14.4 Volts.

If you NEED to stop run on..Always pull the +wire from the coil..not the battery cable or alternator wires..this just destroys modern Electronics.

My Nickels Worth..

Doc

[crash70rs]

The alt. is wired correctly, and the ASD is working correctly (tried a new one). All the wires to/from seems in tact, no splices or visible damage.

I pulled the side of the alt that goes to 12v ignition, mostly as a sanity check.

I believe one of the pins you mention (I don't have the schematic here) is a +12v ref or power from ignition, the other the equivlant of a voltage regulator fior the alt.

I do not recall mentioning 30-60v, if I did it was in error. While running on wire gets +12v, the other (from the computer) get +2-4v (the range i seen while measuring.
When the car continues run-on, bot these leads go to approximatly +7v. I will double check that number.

It seems the computer is working correctly (voltage regulaltor portion) as it correctly compensates for extra electrical load (fan, lights. ect.)

The code "Alt. field coil open/shorted" has been around prior to me messing with anything, and I just assumed it was telling me the alternator was cooked. Unfortunalty I neglected to check again after I replaced the alt. and otherwise forgot about. I did clear the codes and it still come on.

Thank you for the words of caution/wisdom. They are appreciated.

[docvette]

Doc here,

Put a 1N4001 Diode on the + Side of the coil wire.

It WON"T cure the problem..but it will safely shut off every time until you can unwrap the harness and hand over hand the wires.

Doc