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Chevrolet Impala Lighting/Electrical Problems



  • jntjnt Posts: 316
    I believe the yellowish material on the circuit board either is solder flux material or conformal coating. The use of conformal coating is very common on automotive products

    Solder flux is used for helping the soldering process: make solder flows better and reduce short between adjacent pins. It is no difference than the solder flux that we use at home for soldering water copper pipes.

    The conformal coating material is a liquid coating to insulate the electrical circuits from moiture condensation (that causes virtual short or detuning circuitries). That use is common in some vehicle modules

    I do not think they are electrical burn marks. Besides, if they are burn marks, you should recognize the electrical burn smell right away upon opening this box.

    I have read somewhere in the Impala discussions about the cause of most BCM module problem is on the main connectors themselves : intermitten due to loose terminals (metal mating parts of the connectors). That causes the BCM computer to go crazy.

  • Thank you very much for the information. I have decided to have a mechanic permanently bypass the passlock system. Hopefully that will work.
  • I replaced one of the modules but nothing changed. There is supposed to be a 30 amp fuse that may be the culprit but I can't seem to find it. Does any one have a clue as to where it is? There are a bunch of wires that I am afraid to move. Could it be under there?
  • Hi -

    On our '00 Impala, it has the "homelink" feature and all works fine except that the outside temperature reading is about 10-12 degrees colder than actual.

    I've noticed a variable setting, but nothing about it in manual and from "trying it" I can't seem to calibrate it.

    Does anyone know how to calibrate this thermometer setting ?

    Thanks in advance !
  • fnonefnone Posts: 4
    I have the same problem and have not yet fixed it. The calibration is for the compass zone, not the temperature on my car. I'm guessing that I'll have to replace the computer or the temp sensor. I decided to wait until I need service on something else before I have it looked at.
  • lindaflindaf Posts: 2
    I have the same problem lot of you are having. The security light will come on then off again. I have been stranded about 4 times where my car would not start after it had been sitting a while. Called dealership they advised this big routine to go through. I know I have to wait 10 mins then it will start. Very frustrating. My impala is 2001. Dealership cannot find problem unless it is happening when I bring it in. Called GM to ask for recall. Have not heard anything back yet. :sick:
  • Please tell us how you found a mechanic that could bypass the passlock system. Dealer? Independent?
  • Did the $12.00 key fix your problem? Thanks
  • My father inlaw's Impala is driving him nuts with the intermittent security light and no start condition. The dealer suggests he spend $700 on a new module but they cant guarantee that will fix it. They even gave him a copy of the bulletin, doc ID 1547837 below with his written estimate.

    "BCM - Security Lamp ON/No Crank/DTC's Set
    Bulletin No.: 04-08-47-003
    Date: August 31, 2004
    Security Light On, Engine Will Not Crank, Diagnostic Trouble Codes B2958 and/or B2960 (Repair Poor Terminal Connections at Body Control Module)
    2000-2005 Chevrolet Impala, Monte Carlo
    Some customers may comment on an engine that will not crank. Others may comment on the security light
    being on. Technicians may find DTCs (diagnostic trouble codes) B2958 and/or B2960.
    Cause: These conditions may have several different causes. In each case, however, testing of the BCMs (Body
    Control Modules) replaced for these conditions are frequently found to be operating to specifications and are
    believed to have been replaced needlessly.

    The following are the likely causes of these conditions:
    1. Damaged or loose/unseated terminals in these BCM connectors may cause a security light or no start
    ^ BCM connector C1 (24-way, pink in color), terminal B9 (white wire, circuit 1459)
    ^ BCM connector C1 (24-way, pink in color), terminal B12 (black wire, circuit 1835)
    ^ BCM connector C2 (24-way, grey in color), terminal A3 (yellow wire, circuit 1836)

    Blah blah blah, etc...etc..

    SO...they use the words "replaced needlessly" and "likely caused by" yet attached to this I have an estimate to replace part# GM10489422 module at a cost of $700 total parts including labour. I now find that the part number is an Electric Ignition Control Module. Huh??

    I want to get the BCM removed so anyone with info or tips please let me know. The yellow spots on the circuit board someone is referring to are indeed solder flux, a very normal thing to find and is NOT the problem. What one needs to look for is cracked solder connections. Those usually show up as a small crack or ring around the solder connection and most often when found are on the larger type connections such as the posts which a plug goes onto.

    Cracked, cold or otherwise poor solder connections is imho probably the single most common reason for equipment failure, of any type. The second most common problem is electrolytic capacitor failure which has become almost epidemic in the past few years. I dont see any electrolytic capacitors of crap on the picture of the BCM module.

    I'm an electronic tech and in the past 25 years or so I've repaired 1,000's of bad solder connections on circuit boards and modules in various equipment (not vehicles) and the pattern is always the same. This module is not any different in construction than one found in a TV, computer or similar electronic device. I need to get it out and inspect it closely. While it's out I will most likely resolder all connections on the plug posts and check the plugs for corrosion or other problems.

    Now I need to be able to get it out, if the father inlaw allows me to try this. Any info someone may have to get this thing out would be appreciated :)

    I would of course post my findings here if I got through with the removal, inspection (and hopefully repair).
  • Eray2000, thx for the pictures of the BCM! Those are great high res pictures and I can almost say that some of those solder connections along that row by the grey socket may be bad. Thats on the file bcm02.jpg. Fantastic shot!

    I know if that was my module, out of the car like that one is, I'd be resoldering every one of those joints.
  • jntjnt Posts: 316
    The following are the likely causes of these conditions:
    1. Damaged or loose/unseated terminals in these BCM connectors may cause a security light or no start
    ^ BCM connector C1 (24-way, pink in color), terminal B9 (white wire, circuit 1459)
    ^ BCM connector C1 (24-way, pink in color), terminal B12 (black wire, circuit 1835)
    ^ BCM connector C2 (24-way, grey in color), terminal A3 (yellow wire, circuit 183

    Based on this info, it is not the BCM pin (inside the BCM module) not soldered properly. The problem is limited to the vehicle wiring harness that is connected to the BCM module.

    Every copper wire is terminated with a metal terminal by crimping . The terminals (female type) are then inserted into the vehicle connector housing. I bet either the crimping job were bad or the terminals got loose from the connector housing and then cause electrical disconnection.

    Good luck

  • kdconodkdconod Posts: 53
    If any of you have the dreaded turn signal/hazard light problem, you can replace the hazard switch yourself in about ten minutes with simple tools.

    Here's some photos of how to do it:

    The hazard switch is GM part #10359031
  • Thank you so much for this info!! I will be ordering the switch tomorrow and replacing it myself. :)
  • shadow5599, thank you very much for pointing out the possible bad solder connections. Recently, I had a mechanic to permanently bypass the PASSLOCK system through PCM code hacking. Not sure if it works or not and I have to wait for several months to see. I will post back when I am sure the problem is fixed.

    In fact very few mechanics have the equipment and knowledge to perform this kind of hacking (I believe most dealers don't know how to do that either except ripping you off for no-sure fix). I also found a link at other forums

    Follow the procedure and you should be able to bypass the PASSLOCK system too.

    Good luck to everyone who has trouble with the security/no start problem.
  • I havent looked at the car yet but not quite understanding the bypass procedure. Especially where the resistor goes. I can see it goes between the black wire and a point labeled as 87. Where is this point 87 on the diagram physically located? Is that block they show a relay or?
  • I always seem to have water/condensation in my driver side headlight and foglight. About a year ago I took out my headlight, dried it out with a heatgun and put a little clear silicone sealer around the edge to make sure it wouldn't leak, but the darn thing still has water in it, as does the foglight. Driver side only which is weird, passenger side is fine.

    Any ideas on where this water could be coming from??
  • Just.curious.if.this.fixed.your.problems.I.have.the.exact.
  • Replace the "passlock" sensor, that should fix the "no-start" problem.

  • I have moisture in my headlights too.

    I tried silicone around the headlight lenses. Seemed to lessen the amount of water/moisture.
    Problem still occurs occasionally!

    My 02 Impala is a total lemon!
    I will never buy CHEVY again!

    I had to have the dealer replace the BCM right after the factory warranty ran out!!

    Then a year later the "Passlock" sensor went bad!

    Not to mention I have to put stop leak in the radiator because the intake manifold gasket leaks!

    My High/Low Beam combination switch doesmn't work properly!
    Some times when I switch to high beam the lights shut off!

    If GM doesn't recall these defective headlight switches, some one is going to get killed!! Can you say "Class action law suit?" :lemon:

    My new Japanese SUV hasn't given me any problems!
  • I was replying to "lindaf"

    What year Impala do you have? and what model?

    I would replace the "passlock" sensor if you have the intermittant "no start" problem.

    Typical symptoms of a defective BCM is the clicking noise in the dash, air bag warning lights stay on, headlights blink erratically, and security light flashes.
  • I have had my Impala for 2 years. Never had any problems until my warranty expired. Now I am having electrical issues (so I believe). One of my low beam/daytime running lights went out, so I had it replaced. Within a few days, the light went out again, then I noticed both of my lights were out. I had finally found noticed that the connectors for the lights were totally fried. Had them replaced about 2 weeks ago. Today, my the driverside light is out again! Checked the connectors, fine. Checked the bulb, fine. Anyone have any ideas before I spend a whole bunch of money I don't have to fix a car that I've already put way tooo much money into???

  • emx72emx72 Posts: 3
    had the same problem check your fuse, and although it may look good take a closer look, my fuse was really popped but was connected by like a hairline causing the connector to melt and the other problems you mentioned, don't just test the fuse actually pull it out to look at it. Regards
  • To those with similar problems, the intermittent no start/security light thing.
    If you have the original battery, change it.
    That solved my father inlaw's problem. He changed the battery about 4 weeks ago and the no start problem hasnt occurred since!
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    I've got a 2000 Impala, and I believe I've changed the battery 3 times in the last 8 years. Each time prior to the battery going out, I had weird electrical things happening that didn't make any sense, but that cleared up once the battery was replaced. I know the last time I had trouble with the steering wheel mounted radio controls; I'd hit the button to advance to the next station, and the radio would seek indefinitely and such. I figured the radio was going out, but then I was out one night and got in the car and it wouldn't start. Called AAA and got a jump, took the battery to AutoZone and had it tested, and it was bad. The thing I wonder is if maybe there isn't a problem with the alternator that is ultimately causing the batteries to go bad or not.

    In any event, if you start experiencing weird electrical issues with your Impala, you might want to pack a set of jumper cables just in case! :-)
  • 77067706 Posts: 2
    My headlights and turn signals stop working and start working again randomly.The dealers say`s I need a new multipurpose switch.$365 plus $140 labor.Is this a common problem because it sounds like a factory defect.I am thinking of contacting the BBB Autoline to see if I can get the manufacturer to reimburse the cost to me.
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    If your turn signals can be "jump started" by depressing the hazard switch, that's probably the cause of your turn signal problem. Don't know about the headlights, but when my turn signals quit working all that was required was replacing the hazard switch. Granted your problem could be different, but if that's all you need it is something you can pretty easily do yourself, if you're not too scared to take the front fascia of your dash off to get to the back of the panel to pop out the switch. Don't remember the cost of the part (or the number at this point), but the cost of the part was well under $100. If you can't find more details in this forum, you might also check and search their threads for specifics.
  • I have a 00 Impala and now when it gets dark out and the automatic lighting kicks in all the lights on the dash, radio, console shifter go extremely dim, heater control lights are dim, to the point where I can't even see the time on the radio, nor the speedometer needle. During the day when the sensor kicks back to day mode the radio lights light up full and I have no other issues. Any one else have this problem?? Thanks everyone
  • cnwcnw Posts: 105
    Do the lights respond to the control knob that adjust brightness? The same knob is generally the one that manually turns on the interior light. There may be a malfunction in that switch and resistor. Clark
  • They don't respond,they just stay dim all the time, even if I try to turn up/down the brightness. If the switch/resistor is bad would the lights be on dim like mine are?? Is the switch/resistor an all in the one piece that is right behind panel?? Easy to replace?? Cost?? Again thanks again for the help
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