CRX ECU solders cracked? Also ECU v ELD charge problem.

Discussion in 'General Motoring' started by Meathead, Feb 24, 2008.

  1. Meathead

    Meathead Guest

    1988 CRX DX M/T. And some symptoms you might need to know if you read
    far enough into this. New batt and alt. I do pizza driving at night,
    so consider. Full batt will run down, dash lights dim, headlights,
    etc at idle. You know the drill. NO parasitic draw (tested simple
    way and in series w/ batt). Accelerate and lights all come back up
    almost like the flip of a switch. Problem has become more and more
    persistent frequent. Early on before new alt and batt, prob might
    show up for a few hours and disappear for 2 weeks. Or might be
    obnoxious off/onn for two days and disappear for 2 weeks. Car might
    get better/charge left idling. Might not. Idiot light OK. Idiot
    light not On. I'm knind of lost. Bored or interested? read on.
    Where should I go from here? Also have had TC's for ELD 4-5 months
    ago...not one since. Also have had code for TP sensor. No other mods
    or tinkering that might have caused prob. Car came to me this way. I
    did batt and alt for sure fix :)

    First off. I opened the ECU removing the four screws. Looking in I
    see the hold down screws for the board. Now, nearby are some LARGE
    soldered spots. Size-wise these "soldered lumps" look like what a
    soldered-over screw head would look like. Not saying they are screws,
    but the size and elevation/thickness is similar. Not your typical
    board size solder. These solders appear to have a ring/crack near the
    base where the solder intersects the board. Anyone else see this? I
    can't tell if they are actual cracks or not.

    I arrive here because I am having a charging prob. New battery (like
    I just bought it and put it in "new" b'cause I think the problem
    trashed the last "new" one from only 6-9 months ago.) New alternator
    about 6 months ago too. Am tracking through the Helms trying to find
    culprit other than an open circuit/cracked wire (pain in the butt) via
    the troubleshoot schematics.

    One helpful question I need answered: If procedure says check for
    "battery voltage" under certain conditions. I assume it means the
    test should provide batt voltage as the battery reads at the same
    instance NOT a standardized 12.5 or 14, etc? Am i correct?

    So I (think) I have gotten it down to the ECU or the ELD. Answer to
    the battery V question will clarify where I stand. In ECU case I am
    stuck at hooking the "test harness". Obviously don't have and don't
    know how to proceed.
    Please, please give me some pointers, gang. Much obliged.

    Meathead, Feb 24, 2008
  2. Meathead

    Graham W Guest

    I don't understand what your battery voltage is. Please elucidate.
    Graham W, Feb 24, 2008
  3. Meathead

    jim beam Guest

    1. ecu is always the /last/ suspect, not the first. do /not/ mess with
    it unless you have a definite diagnosis.

    2. if the battery is not charging and the battery is guaranteed good,
    you have a charging circuit problem.

    suggest getting the alternator tested. cheapo rebuilds are dreadful
    component quality and it's easily possible you have a dud.

    once you eliminate problems with the charging circuit, by far the most
    likely cause, check for draw by going through the small fuses in the
    fuse box and testing for current drain on each circuit. eld problem
    will likely disappear along with the charging circuit problem since the
    eld is solid state and most unlikely to fail.

    general note on error codes - reset and see if it comes back. random
    error codes when you have a known electrical problem are not reliable.
    jim beam, Feb 24, 2008
  4. Meathead

    Meatman Guest

    Thanks Beamer. If I may thin it out a bit and's the
    simple version of the original post:
    Got car. All seems fine for weeks. Notice weak headlights/dash
    lights one night at idle while parked (pizza delivery). RPMs up =
    charging/lights brighten. Problem goes away same night...all normal.
    No problem 2 weeks then go out to dead batt in morning. Buy new
    battery. A-OK for a week...problem back one night...goes away same
    night. Repeat at random intervals for varying amounts of time from 15
    minutes to 2 hours. Replace alternator. A-OK for 10 days-2 weeks.
    Problem back "seemingly" at random but more and more frequently and
    longer lasting too. One night driving at 45mph so little juice that
    stereo powers off and on and rpm's don't help. Check parasitic draw
    the simple way w/ batt ground off and also in series w/ batt. Test
    light does not light (tested many times through this whole ordeal).
    Have battery tested. Battery is toast. Replace battery. And here I
    am today. Car not driven since and sitting w/ fresh battery. Have
    gone through ELD troubleshoot/test. Appears OK. Now going through
    charging/alt circuit test and don't know how to proceed as I don't
    have the test harness to attach to the ECU. How to continue???

    And final question re: Helms test procedures. Some troubleshoots say
    "is voltage 'X'?" While other parts say "is there battery voltage" at
    this terminal/connector. I assume "is there batt voltage?" means the
    same voltage reading that I would get if I took a reading on the
    battery at the same time under the same conditions...NOT just any ole
    voltage, right?

    So, if I can get throught the test harness part I should know
    something. If that tests out OK, am I just looking for a damn
    grounded wire or broken wire? Should prove fun. Help if you can.
    Thank you kindly.

    Meatman, Mar 6, 2008
  5. Meathead

    jim beam Guest

    it's very unlikely it's ecu or eld. i'd therefore spend my time hunting
    down other electrical problems.

    you're looking at transistorized electronics so you're going to get
    voltages different to battery. i'm rusty on this stuff, but iirc, you
    get 0.7V drop across a silicon junction, add that a couple of times, and
    you'll see variance. and many electronic circuits of this era run on 5V.

    definitely. poorly wired stereos are a favorite along with alarms and
    aftermarket lights. especially if you have "extra" wires running from
    battery terminals that are unfused.

    sorry - this is a job for a meter, patience, and good old fashioned
    detective work. look for obvious wiring mess-ups. and bad earth
    connections. the test procedure assumes things are wired right, so
    while it's a good guide, you have to use some logic as well. don't be
    afraid to get a re-built alternator re-rested. seriously, the bad ones
    can be awful. lastly, unless you've eliminated all other options,
    assume the ecu and eld are ok. but that said, my local junkyard will
    get you replacements for both for less than $50, so it's relatively
    cheap to "test" with replacements.
    jim beam, Mar 6, 2008
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