Ad Radar

Automotive Forums  Where Car Enthusiasts Go to Discuss Cars Online

  
 
 
Home | Active Posts | Search | Log In / Register | Terms | FAQs
Xml
1 |  2 |  Next   | Last 
Item Posts   

POSSIBLE PCM PROBLEM

 
 | 
mlevergne mlevergne
New User | Posts: 10 | Joined: 04/12
Posted: 04/21/12
05:36 AM

OK here is the deal I have a 1996 Chrysler Concorde LXi.

My Battery went dead and I went to jump off my car. Well I wasnt paying attention and Cross Wired the Cables. White Smoke was coming from beside the battery (near the PCM).  Immediatly took off cables let the smoke clear and went to jump off the car again, but once I had power going to the battery to jump off car Everything went berserk. Lights(head lamps) flickers off and on, Harzard lights going off and on, Horn blowing, and A/C Fan blows all that I know of that was going on ATM. I go to start the car it starts but then dies (with cables on from other vechile and with out cables on).

I went about my business to trouble shoot to check out what was burnt. Checked the PCM no burnt smell at all. Checked all wires where the smoke was coming from. Even pulled off the fuse box to see if there was anything burnt.(NONE).  Was Curious to know if there is a way to figure out what is wrong.  Confused

Anytype of help would be greatly appreciated.  

waynep71222 waynep71222
Guru | Posts: 825 | Joined: 03/12
Posted: 04/21/12
06:54 AM

charge the battery...

you will want to clean the battery cables.. perhaps done.

you will want to take apart the various battery cable connections and clean the ring terminals.. then reassemble..

can you see if any codes are stored by flipping the ignition key ON  off ON off ON  off ON..  without starting the motor.. the odometer should change to code display..  

waynep71222 waynep71222
Guru | Posts: 825 | Joined: 03/12
Posted: 04/21/12
06:55 AM

do you have wiring diagrams???

do you have a digital volt meter and some kind of scan tool to look at live data...  

mlevergne mlevergne
New User | Posts: 10 | Joined: 04/12
Posted: 04/21/12
06:07 PM

My electrical system is going haywire. Is the main issue at the moment.  

waynep71222 waynep71222
Guru | Posts: 825 | Joined: 03/12
Posted: 04/21/12
06:45 PM

log in.. check your messages to the left of where you log out at..

i have a link for you.. that might help..

were you able to get any codes...  

mlevergne mlevergne
New User | Posts: 10 | Joined: 04/12
Posted: 04/21/12
09:19 PM

Icon Quotewaynep71222:
log in.. check your messages to the left of where you log out at..

i have a link for you.. that might help..

were you able to get any codes...


No I was not able to get any codes... Confused  

waynep71222 waynep71222
Guru | Posts: 825 | Joined: 03/12
Posted: 04/21/12
10:30 PM

take your digital volt meter...  turn the headlights on.. turn the key on.. attempt some voltage drop tests...

20 volts DC setting..

negative battery post.. yes i know its hard to get to .. to the engine block while somebody cranks the engine..   reading while cranking should be less than 0.2 volts..  while cranking...

next check from the negative post to the body.. with the headlights on and someone is cranking the engine.. this i would expect to be a lot lower.. 0.02 volts..

engine to body..  with headlight on.. and cranking.. 0.02 volts..

then and the positive battery post is really hard to get to..

positive battery post to various connections like in the end of the relay box where the main wire comes in.. while cranking..   headlights on...

why.. when you got smoke.. you got something hot.. i am worried about some of the connections that they might have opened...

have can you find the blue and the green wire to the back of the alternator..   disconnect the green wire..  there is usually a wiring harness connector to the alternator that makes this easy if you take the connector apart.. then figure out how to determinate the green wire from either side..    the blue wire is 12 volt Positive for the windings.. the green wire is what the computer pulls in pulses to ground to complete the circuit to create the magnetic field to make the alternator charge.. why... if the diodes are shot do to the reversed connection..  it could be putting out all kinds of AC voltage into the DC circuits and fool the various computers like the BCM stashed under the dash board into turning on random things..

since the car won't start it might be hard to get an AC volt reading off the alternator or at the jump start connections.. less than 0.05 volts AC should be measured at the alternator output if the engine ran...

with the computer controls... any is bad..  why not just take it off and test the alternator.. its probably a pain on that model to get it off..

trying to fix things over the internet is hard.. finding electrical issues is really hard .. requires testing.. as you well know..


just a month ago.. i managed to use a customers brand new set of jumper cables..  i was following the wire color.. he said.. they are brand new.. just out of the package..  that was reasonable..  i hooked them up and my engine started to slow way down do to the heavy load on the alternator..  i removed the cables..  then found that this pair were assembled backwards..    it had red and black grips on one end.. and blue and black on the other..  but one side was reversed..  at least i did not do any damage.. other than always using my own set..  or checking the set i use first..  even if they are brand new out of the package..

identify each device thats acting up.. go through the trouble shooting on that circuit.

this is after the voltage drop tests..

last question.. do you have communication with an OBD2 scan tool.. can you see the live data stream???  

mlevergne mlevergne
New User | Posts: 10 | Joined: 04/12
Posted: 04/22/12
01:06 AM

Icon Quotewaynep71222:
take your digital volt meter...  turn the headlights on.. turn the key on.. attempt some voltage drop tests...

20 volts DC setting..

negative battery post.. yes i know its hard to get to .. to the engine block while somebody cranks the engine..   reading while cranking should be less than 0.2 volts..  while cranking...

next check from the negative post to the body.. with the headlights on and someone is cranking the engine.. this i would expect to be a lot lower.. 0.02 volts..

engine to body..  with headlight on.. and cranking.. 0.02 volts..

then and the positive battery post is really hard to get to..

positive battery post to various connections like in the end of the relay box where the main wire comes in.. while cranking..   headlights on...

why.. when you got smoke.. you got something hot.. i am worried about some of the connections that they might have opened...

have can you find the blue and the green wire to the back of the alternator..   disconnect the green wire..  there is usually a wiring harness connector to the alternator that makes this easy if you take the connector apart.. then figure out how to determinate the green wire from either side..    the blue wire is 12 volt Positive for the windings.. the green wire is what the computer pulls in pulses to ground to complete the circuit to create the magnetic field to make the alternator charge.. why... if the diodes are shot do to the reversed connection..  it could be putting out all kinds of AC voltage into the DC circuits and fool the various computers like the BCM stashed under the dash board into turning on random things..

since the car won't start it might be hard to get an AC volt reading off the alternator or at the jump start connections.. less than 0.05 volts AC should be measured at the alternator output if the engine ran...

with the computer controls... any is bad..  why not just take it off and test the alternator.. its probably a pain on that model to get it off..

trying to fix things over the internet is hard.. finding electrical issues is really hard .. requires testing.. as you well know..


just a month ago.. i managed to use a customers brand new set of jumper cables..  i was following the wire color.. he said.. they are brand new.. just out of the package..  that was reasonable..  i hooked them up and my engine started to slow way down do to the heavy load on the alternator..  i removed the cables..  then found that this pair were assembled backwards..    it had red and black grips on one end.. and blue and black on the other..  but one side was reversed..  at least i did not do any damage.. other than always using my own set..  or checking the set i use first..  even if they are brand new out of the package..

identify each device thats acting up.. go through the trouble shooting on that circuit.

this is after the voltage drop tests..

last question.. do you have communication with an OBD2 scan tool.. can you see the live data stream???


Ok I am not all that smart with the stuff. I know the basics about  fixing things on a vechile I am not certain what all of this means. But I can say I am not sure what an OBD2 scan tool is. I have limited access to tools.

To go to back to the topic about the altenator. So you saying the computer pulls in pulses from all of the electronics. If that is the case could that mean that the computer(PCM/ECM) is bad/shorted out? Since all of the electronics were going off in Pulses/Surges of power passing through them. Would it be safe to say that the PCM/ECM is bad or shorted out. I have talked to a few other people and was told that I could possibly change out the battery and it would be ok, Due to the fact that I changed the palarity of the battery by crossing the positive/negative terminals while attempting to jump off the car.  

mlevergne mlevergne
New User | Posts: 10 | Joined: 04/12
Posted: 04/22/12
04:02 AM

So also what do I need to do? Test my Alternater?

How do I determine what is wrong?

Confused  

waynep71222 waynep71222
Guru | Posts: 825 | Joined: 03/12
Posted: 04/22/12
05:59 AM

since you have the factory service manual... it shows a most of the tests you need.. but does not show tests for reversed polarity of the jump start..

what to look for in the alternator..   when it gets hit with reversed polarity ... the diode might have taken a big hit... so there might be leaking AC voltage through.. into the DC system..  this will totally freak out the computers...




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

the reason i want you to go over the grounds and the positive connections.. i have found so many of them dirty on those models.. and when you got smoke.. something was burning.. the only thing i can think of is one of the connections some place...

if you have a bad ground connection.. since many of the things in the car are computer operated by the BCM under the dash board..    it will just freak out..

remember.. electrons flow from NEGATIVE to positive..  so if you have a bad ground.. you may NOT have enough electrons to operate the circuit..    but the electrons will try to get through somehow...

so they may be taking short cuts through different circuits ...    causing the rest of the electrical system to go haywire.


~~~~~~~~~~~~~~~~~~~~~~~~~~

if the fire department was out spraying water from a bunch of hoses..   and you parked on the hose from the hydrant to the truck..  all the hoses would go dry except perhaps one at a time..

a bad electrical connection is a restriction..

can you post what circuits go crazy...

if its just the headlights and the horn honking.. i would start with the security section part of the factory manual..   as that will prevent you from starting the car for more than a second..  

mlevergne mlevergne
New User | Posts: 10 | Joined: 04/12
Posted: 04/22/12
03:57 PM

Its the head lights, hazardous lights, turn signals, and horn. That I know of that is noticable.I have pulled the fuses to these circuits to make them stop  

waynep71222 waynep71222
Guru | Posts: 825 | Joined: 03/12
Posted: 04/22/12
05:06 PM

section 8P is the keyless entry section...

with the doors all closed..  does the keyless entry fob lock and then unlock the doors??  

mlevergne mlevergne
New User | Posts: 10 | Joined: 04/12
Posted: 04/22/12
06:07 PM

no I think that is because the battery is dead...  

mlevergne mlevergne
New User | Posts: 10 | Joined: 04/12
Posted: 04/22/12
06:08 PM

but it didnt work when I tried it  

waynep71222 waynep71222
Guru | Posts: 825 | Joined: 03/12
Posted: 04/22/12
08:26 PM

well... revert to plan ONE.. discharged batteries on a computerized car...




  recharge battery  fully before proceeding with any repairs...




what that means.. at idle.. the ALTERNATOR does NOT put out enough current to keep the engine going if its trying to charge a deeply discharged battery...

the discharged battery with the engine at idle will pull the voltage so low.. the system will GO HAYWIRE.. like you have experienced..

all the relay driven devices are tripping out..

jump starting or boosting the battery WILL NOT WORK.. you may only damage more parts..  including the alternator..

the alternator is NOT DESIGNED TO recharge a deeply discharged battery.. its make to TOP off the charge...  and supply voltage to the car..

the diodes in the alternator will not last while attempting to recharge a deeply discharged battery..  they will get hot and fail..

i have only been doing feed back carbs and fuel injection for 30 years..   the first class i got at the GM training center was in 1980...  on feed back carbs..  the next years course actually had the use of a scan tool .. the next.. was when TBI came out.. then TPI..    every fuel injection and engine control system uses the same theory..  so once you know one.. you know most of them.. except for slight differences..  

1 |  2 |  Next   | Last 
Xml
Showbuyersguide Hide2
Get a free and easy new car
price quote in minutes
Button Getmyprice

Research Categories:

Sponsored Links

 
 
  • Trade-in-Value.com