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So, I rewired my car...

Discussion in 'Modified Alpine' started by cnalbers, Mar 4, 2022.

  1. cnalbers

    cnalbers Donation Time

    After reading Tim Raymond's thread on rewiring and getting his guide, I decided to rewire my car. I tried to follow his setup as closely as possible, but since my car has a Delco CS130 alternator, I needed to make some changes. Everything works and runs well, however, now my ammeter pegs immediately because my alternator is putting out max voltage constantly (14.2v), until the internal voltage regulator overheats and it cuts off, only to start up again after it cools off. One voltage regulator has already blown... it's only a matter of time before the next one blows. The alternator is a new rebuild, as is the voltage reg... however, I drove my car for about 30 mins the other day and the reg is turning off faster now. I have a new regulator on the way.

    I have no idea how to troubleshoot this. I had thought to get it running and just start pulling fuses one by one to see if it affected the alt output, but the voltage reg started cutting out too quickly and I didn't want to kill it by keeping the engine running too long...

    On my alternator there are only 2 wires being used on the SFLP connector; the S wire is connected to the alternator as pictured (Batt), the L wire is connected to the warning light bulb on the dash. The wire on the Batt terminal in the drawing (Blk) goes to the -Ammeter terminal; the + Ammeter terminal is connected to the Battery through the Batt terminal on the Starter Solenoid. I guessing my problem is here, but I don't know...

    Any advice? I am weak when it comes to electrics...

    Attached Files:

    Paul A likes this.
  2. Toyanvil

    Toyanvil Diamond Level Sponsor

    I would start by by-passing the Ammeter. I don't think alternators like Ammeters, I changed mine to a Voltmeter.
    Paul A likes this.
  3. cnalbers

    cnalbers Donation Time

    I'll give it a try. I converted to the CS130 from the Lucas alt many years ago and never had any issues like this, so something in the rewire must have caused it.
  4. JR66

    JR66 Platinum Level Sponsor

    Make sure the alternator is grounded well. It's a good idea to connect a separate ground wire to the case. A poor ground may not be the problem with yours but it's good practice. Another good practice (but probably not causing your problem) is to connect the S wire at the solenoid or nearer to the load than directly to the Bat. connection on the alternator.
  5. JR66

    JR66 Platinum Level Sponsor

    Also make sure the S wire has good continuity and no loose or corroded connectors. It's job is to tell the regulator when the battery voltage is adequate and to cut back on output current.
  6. hartmandm

    hartmandm Moderator Diamond Level Sponsor

    The old Lucas ammeters are just a solid wire inside and the magnetic field generated by current flow deflects the needle. The alternator doesn't know it is there.

    loose_electron likes this.
  7. spmdr

    spmdr Donation Time

    What is the GEN/Charge light telling you? Is it acting correctly?

    If the light is not wired correctly, you would likely have issues with the alt.

    IF the light is wired correctly, It sounds like the Alternator is seeing too big of a load.

    The battery is suspect. Is it fully charged?

    After starting, an ammeter SHOULD see high current for a brief time

    but current should start to go down in seconds.

    One thing you could try, is disconnect the Battery (very carefully, keeping sparks away from the battery!)

    after you get the car started.

    Last edited: Mar 6, 2022
  8. cnalbers

    cnalbers Donation Time

    Everything is new... battery, alternator, wiring.

    Warning light comes on when ignition is in ON position and turns off after engine starts. When engine starts the ammeter needle pegs off the scale and STAYS there until (I assume) the voltage regulator overheats and turns off (10min or more), when it goes off peg it reads NEG on the ammeter, but only a few mm left of center. Minutes later (not sure how many, 5-10?) the ammeter will peg again but it won't stay that way as long... the ammeter then reads slightly NEG a few mm. I think the voltage regulator is starting to fail, as the behavior is stopping sooner than it has in the past... eventually it will give up and stop charging... I have already been through this once before. Took the alt to the manufacturer/rebuilder and he confirmed the volt reg failed and replaced it.

    Prior to the rewire my ammeter would only peak to about half way between mid point and max scale, and that was because I was running the 400W stereo. Under normal conditions the ammeter would run just a few mm to the charge side.
  9. Tom H

    Tom H Platinum Level Sponsor

    So you have nothing connected to the F terminal? The drawing says " Must see hot wire when ignition is on" . This means it must be connected to hot wire when ignition is ON. I'm very familiar with electrics, but do not have more detail on how this Alt actually works. I don't know what's going on here, but I am puzzled by your lack of wiring to the F terminal.

    On a separate issue. tell me what you ammeter reads when the car is not running but you turn the headlights on

    Last edited: Mar 6, 2022
  10. cnalbers

    cnalbers Donation Time

    Since I converted to the GM alternator some 30 years ago, it has always been wired this way. I have never had a wire connected to the Field terminal. When the car is off and the lights are on the ammeter reads NEG a few mm's to the left of center.
  11. Paul A

    Paul A Alpine Registry Curator Platinum Level Sponsor

    Is your ammeter a 30 amp unit? There are 50 amp units. Is your ammeter grounding? For what it is worth you might consider using a voltmeter rather than an ammeter. I have successfully used GM alternators for many years with no issues.
  12. cnalbers

    cnalbers Donation Time

    I just ordered a Lucas voltmeter. The guy at the instrument shop told me that my 105amp alternator will always make the ammeter peg... the odd thing is, it never did it before the rewire. Mine is a 35amp model.
    Paul A likes this.

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