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voltage regulator?

Discussion in 'EEK! - Every Extended-K Car' started by willrappold, Jan 31, 2015.

  1. Cornupenuria

    Cornupenuria Well-Known Member

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    I wonder if a poor alternator case to engine ground or poor engine to body ground could cause those same symptoms. I suppose battery negative cable to engine corrosion could cause them too.
     
  2. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    Poor ground will typically cause a higher-than-normal charging voltage. Bad field connections can cause undercharging.
     
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  3. awyseguy

    awyseguy Well-Known Member

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    I added an external regulator to my '86 Shelby Charger back in the mid 90's; been there ever since. If I ever change out the computer, maybe I'll let it take control of the alternator again. Till then, I'll leave it like it is. I wired the external in parallel with the computer.. So basically, it thinks it's doing its job still.
     
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  4. T-Dot25

    T-Dot25 Active Member

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    For me, and usually on sites like this, I always think that people understand that the battery is always the first to check in these circumstances, so sometimes I forget who my audience is and I omit its mention. But I have to remember that not everyone who comes to this site is fully fluent in automotive theory and practice and I like to think that most who are already members or use this site have experience under their belt. So, I will keep that in mind and thanks for that reminder floridaman, and agreed, the battery will need a load test if one hasn't been done.

    http://www.aa1car.com/library/charging_checks.htm

    @ willrappold:

    Sometimes, and this does happen if the alternator is known to be bad which in your case it has been tested and found to be so, these things come in twos. A malfunctioning or bad alternator can impact not just the battery but other components as well, and so usually the batt. and alt. will need to be replaced. The only way to determine that is to do a load test on the battery. There could also be a very nasty parasitic draw elsewhere, however, batteries that are affected can show signs of both an internal open or short through dead cells or arcing of the plates (fusion), creating both undercharging and overcharging situations. The load test will definitely tell you the necessary related amp support from the battery when a load is applied because you have already replaced the alternator as a source of one problem.

    Either way, you have to check and be sure of everything: your charging system involves all components related (alternator, battery, voltage regulation, ECM and wiring). Do not underestimate the power of corroded or sketchy wires. A visual check on wires and connections is sometimes not enough -- and a battery, depending on brand and year of date, including its manufacture to shelf date, can determine when it is time to consider changing. Some are 3 yrs, others roughly 5 years. You're lucky these days to get a good 5 to 7 years out of a battery. They start to deteriorate at the 4 year mark and weaken. Subject to a bad alternator, it can fry and fuse cells (open/short).

    If you google 'check the date on an automotive battery', it will give you that information. It usually is on top, but the actual manufacture date is stamped on the sides of the battery. You can also pull out a multimeter and do some testing yourself. Plenty of info on the web to know how to start this process and the desired multimeter required.

    I think you mentioned in another thread that you have a disability so not sure of how able you are to do this, but I would set up a multimeter to the battery, run the vehicle, and check wires and harness at both idle and with a load (heat, air conditioning, defrost, radio on) and higher rpm's while watching the meter for large spikes (up and down) from the stable multimeter reading from which you are viewing from. You can also do a continuity test without the engine running to check wire resistance and breaks from endpoint to endpoint while handling the wires to check for potential corrosion or break points. It really helps to make sure that wiring is in order and doesn't need to be replaced. Grounds included!

    Keep at it, willrappold.
     
  5. willrappold

    willrappold Active Member

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    ok thanks for everbodys imput im going to try and find a nother pcm conections all look good, now code 47 finally showed up.
     
  6. ImperialCrown

    ImperialCrown Moderator
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    How have you diagnosed that the voltage regulator inside the PCM is bad? You don't want to guess.
    If you ground the green field return wire to the PCM, does the alternator charge 'full-field'? (Only perform this test briefly enough to get a voltmeter reading). The headlamps can be on and may flare brightly. The charging voltage may climb high enough to blow bulbs if left like this for too long. This will prove that the alternator and wiring is OK.
    I have gotten faulty rebuilt alternators out of the box before.
     
  7. John Wood

    John Wood Allpar Legacy

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    I does sound like the original alternator failed the bench test and he replaced it if I read post 14 correctly. He has gone from a code 41 originally to a code 47, at the present time, with the replaced generator. It would be strange to have two unrelated failures in the charging system.
     
  8. willrappold

    willrappold Active Member

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    well i have replaced both logic module and pcm with remanufactored parts, and still have same problem code 47 after driving, does any body know where they put voltage regulaors at?
     
  9. Doug R

    Doug R Member

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    Not on this forum !
     
  10. ImperialCrown

    ImperialCrown Moderator
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    AFAIK your regulator is contained in the Power Module behind the left headlamp.
    If it has changed from a fault code 41 (field switching) to a fault code 47, what charging voltage are you seeing at the battery. If the voltage falls off under load, I would look at a defective alternator or wiring (high resistance) issue.
    I don't know if I can help you with service manual information. I may have a diagnostics manual, but not a service manual. Autozone has minivan wiring diagrams, but those were still carbureted in 1985, not EFI and are different.
    I would look for 1985 Chrysler FWD service manuals. It is a 3 volume set. Vol 1: Chassis/Body, Vol 2: Electrical and Vol 3: Wiring Diagrams.
    Unless someone here has these manuals (1985-1989) and could send you a pdf of the charging section?
     
  11. 85lebaront2

    Level 2 Supporter

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    Ok, I will come in on this one as I have seen this issue before including on a 1992 3500 truck with a Cummins turbo Diesel. A couple of pieces of information, If you have the Bosch alternator, it has a brush holder that is externally removable and it can be replaced with a regulator/brush holder from a VW or Mercedes-Benz with a similar design alternator. The Chrysler 40/90 alternator is designed to use an external regulator. Chrysler used external regulators from the beginning of usage in 1960. With the introduction of the electronic ignition, the regulator was changed from a mechanical unit to an electronic one. Either of these were very simple in wiring, blue, ignition power to regulator, body grounded and an output to the alternator. These work differently in that the voltage for the field is regulated on the input side with the other brush grounded.

    Before I went through all that, I would take a real hard look at two places, the connector between the engine harness and the fusible link cluster near the left shock tower, it is a large pin and socket connector and the design is prone to corrosion and overheating. It isn't quit as bad as Ford's infamous 2G alternator plug though. Take a decent multimeter and with the engine running and the load that causes low voltage on (probably A/C and headlights) measure the voltage at the alternator positive terminal and then at the battery, they should be very close, within a few tenths of a volt. If you find the alternator end is way high when you check it, you have probably located the problem. I do have the complete 1985 FSM set for these cars as I had a 1985 LeBaron convertible (totaled in 2009 by a Mercedes-Benz ML320) but it had the 2.6L Mitsubishi originally with the built in regulator.

    On Chrysler TBI systems, they were introduced in mid 1983 and as was previously posted changed in mid - late 1985 when Holley became Chrysler's source. Even the throttle bodies on the turbo engines starting with the turbo-II and later V6s say "Holley" on them.

    As IC mentioned, I do have the manuals, I will have to get Vol 3 and scan it if you need the diagram. Carbureted models usually had the separate regulator and Chrysler was still building some lower line models (Aries, Reliant, Omni and Horizon along with the minivans) with carbureted 2.2L engines.
     
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  12. willrappold

    willrappold Active Member

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    I finally remembered to reply on the problem, the remanufactured alternator I had put on was bad from the start. After voltage regulator was good (in pcm beside battery), we took the alternator out to see if I could get a replacement since we tried everything else, and they said "we have to put it on our machine first to verify it was bad", and when the test started, it was squealing like a pig, failed right away (wish it did that on the car). So long story short if you have to get a remanufactured alternator even though it says its been tested and good, ask them to put it on the machine anyway to verify it is. Put another alternator on and never had a problem since. knock,knock (wood)
     
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  13. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    I will never use remanufactured alternators if new is available. Autozone sold me 3 defective ones in a row, bad bearings. Failed within 75-200 miles. Finally bought new and no issues.
     
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  14. chuzz

    chuzz Well-Known Member

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    Years ago (1994-1999) when I worked for the Zone, I got into the habit of testing every alternator I sold before it went out the door. I was what they called the Parts Service Manager (PSM) and just considered it good policy for my customers. The manager used to get mad at me for doing that when we were busy, but I prevented a LOT of crappy alternators from going out the door and being returned by angry customers over the years. I had a lot of customers that would only come in and ask for me to help them, rather than other folks working the counter. I STILL won't buy electrical parts from Autozone. I just don't like their lack of quality control.
     
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  15. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    Then there was the used oil pan they sold me as new for $80. It had thick, runny paint all over the outside in a crappy attempt to refurbish it. I was stuck and had to use it to get running again. Within 3 months it was scabbing badly all over the outside.
     
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  16. chuzz

    chuzz Well-Known Member

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    The ONLY reason I do any kind of business with the Zone nowadays is if they're the only place that has or can get a part I need that I just can't wait for. I try my best to avoid them.
     
  17. Doug D

    Doug D Virginia Gentleman

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    I generally avoid AZ unless AA or NAPA doesn't have what I need. Though if AA doesn't have it neither does AZ. Some of the employees at both are clueless. One time a clerk at AA gave me a lost look when I asked if they had Zerex G05 coolant. Said he never heard of it and he was older than me.
     
  18. Duner

    Duner Active Member

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    Being as this thread is 3 years old and probably not relevant to the original poster, I will add you can wire in an external regulator.
    There are numerous instructions available if you do a search. I had a 85 Plymouth 2.2 with TBi and it had an external regulator added and it worked.
     
  19. ImperialCrown

    ImperialCrown Moderator
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    It will charge with an external regulator. The code 41 will still be there with the 'power loss/power limited' warning light on, because the PCM will realize that it does not control charging voltage.
     
  20. RalphP

    Level 2 Supporter

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    There's at least one kit that includes a "field coil" replacement resistor to fool the PCM into thinking it's still controlling the alternator out there. I'm sure a power resistor of appropriate wattage and resistance would also do the job. Won't help if that's what's broken in the ECU, but if it's just driving the field all the time (overcharging), that'll keep the light off.

    RwP
     

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