In-Depth Multiple Electrical Problems After Body, Engine or Gearbox/Transmission Work

Discussion in 'Technical Articles' started by Ichiban, Sunday 12th Feb, 2012.

  1. Ichiban Founder Staff Team

    England CJ Leeds
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    You got your pride and joy back from the garage after some body work, engine or gearbox and you now discover you have with multiple electrical problems for free.

    What causes these issues?
    The culprit could be a bad earth or ground as some people refer to it . If a earth is loose, corroded, painted over, or disconnected, it can cause all sorts of electrical problems with systems and components.

    Here’s just a sample of what could happen:
    • The audio unit or the navigation unit cuts in and out.
    • Instrument panel gauge needles swing back and forth.
    • Power windows, power door locks, or turn signals stop working.
    • System indicators come on (with or without DTCs).
    • The HDS or DTC code readers can’t communicate with the vehicle.
    • Wipers and washers come on with the headlights.
    • The engine cranks but won’t start.
    • The cruise control turns off.

    A bad earth can come from sloppy workmanship at a body shop. In reality earth points aren’t always masked whilst preparing the the vehicle for painting, so you can end up with primer and paint on the body and threads, which acts like an insulator.

    A bad earth can also come from earlier work on the engine or gearbox, or from installation of an aftermarket accessory.

    These earth/grounds are often the culprits:

    • Battery negative terminal and body earth locators.
    • Headlight, turn signal, wiper and washer, tail lamps, and brake light common earth.
    ABS/TCS/VSA earth.
    ECM ground G101 on the engine.
    • Transmission\Gearbox earth points , solenoid earth (if applicable in some auto boxes).

    To find and fix these problems, here’s what you need to do:
    1. Refer to workshop manual or your owners manual for the electrical diagram and look up the earth\ground distribution section, and look for the ground(s) that are related to the symptoms you’re seeing.
    2. Inspect each ground. Make sure it’s got a non-anodized, cutting-type bolt; the threads aren’t corroded
    or painted over; there’s no burr washer being used; and the bolt is nice and snug.
    3. If all fails after this get to a Honda dealer or an auto electrician to carry out parasitic drain test and measure the voltage drop at each affected ground.
     
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  2. AccordCU2 Expert Advisor ★ ★ ★ ★ ★

    Touch wood,never had this problem so far.
     
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  3. Ichiban Founder Staff Team

    England CJ Leeds
    30,126
    6,378
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    Re: Article: Multiple Electrical Problems After Body, Engine, or Gearbox\Transmision

    It’s one of those things that no one looks at or it’s taken for granted, I did when I was learning the trade and learnt it the hard way.

    I had this Morris Minor I worked on in the late 1990 it had it original mechanical fuel pump removed for an electronic fuel pump. These old school pumps worked off the camshaft lobe and were prone to failure so it made sense to go all electric.

    This customer had fitted this pump himself and brought the car to us saying it stops after few miles. There I was thinking a piece of cake can do it in my sleep.

    When we initially looked at the car we replicated the issue, I was instructed by my foreman to throw parts at it .. 90's method of problem solving money was never an object then and fleecing customers was the principle.

    New parts List

    new carb
    new HT leads
    refurbished dizzy
    dizzy cap
    dizzy rotor
    new points
    new condenser,
    spark plugs
    fuel filter

    and still the same.. issue.

    Every time the car went on a long trip it stopped. After a few days I traced it down to the fuel pumps earth lead which was fasten to a cross member. This cross member had spilt two of its rivet so this panel moved on bend causing the panel to flex enough to break the circuit.

    Once the fuel within the carb and the fuel line finished the car stopped. I got the cross member patched up cleaned the earth connectors kept the car for a week put 100 miles on it problem solved. A 10 minute fix and a bill of 900 quid when all that work was not required.
     
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