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Ok, Now it is pissing me off!!!!!Damn electrical problems

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bnc04, May 9, 2006.

  1. bnc04

    bnc04 Guest

    I had this posted in the garage thinking I may get more readers but I am reposting here to see if there is any suggestions that you can come up with.
    Sorry about the long post but I wanted to give all the data I could so as not to waste your time
    88 Chevy 90k on it. Original 350 TBI. A/T

    Purrss along just fine and starts up fine most of the time.

    Periodically, when the brakes are pressed or turn signal is used or blower motor/air or heater is on of windows are used or radio is used or headlights are used or any above the combination is used, the voltage will drop and the truck will start to idle rough. By drop, it could be anywhere from the original 13 down to 10 or 8 or to the red line. Most of the time, it will recover and purr along like nothing happened.

    It also has this symptom, When attempting to start, buzzer, lights etc are all fine and it will not turn over at all. Sometimes, holding the key in the start position (5-20 seconds)will allow it to fire. Sometimes not.

    It stranded the wife yesterday and I need to get this addressed now.

    Yesterday I fixed it by tapping the starter and solenoid, it fired up and ran great all the way home. When home it did not start the first time I tried then fired on the 2nd try. After that it fired fine. It was dark and late so I didn’t do any trouble shooting.

    I did an conversion to a quicksilver megashifter a year or so ago and I can’t remember if the scenario started around that time or not but I think it did.

    I also installed backup lights at about the same time.

    Other than that pretty much stock.

    I have replaced the alternator about 6 months ago. I cleaned out and made sure I had good grounds at the taillights and wiring back there. Replaced the brake plunger actuation switch. The automatic shift coller is fully rotated to the left. I added grounds to the engine compartment, ( firewall to battery) The engine grounds look good and I have continuity from the engine to batt ground and frame to batt ground.

    I’m going to pull the starter this morning and have it tested but it being so intermittent makes me think testing will be of no help.

    Can you guys list what steps I should take to see if I can narrow this down a little?
    I’m nowhere near as savy as you all so you may have to explain things a little more clearly at times.

    Can I start pulling fuses when this happens to see if I can isolate a short somewhere?

    Sorry for the long post, But I have a few hours t lay with it this morning and this weekend would like to get a game plan together to fix this thing.

    Thanks for any help and suggestions. I’ll write them all down and start looking at each one.
    Brett in Colorado

    Another update if this helps.
    Volts across batt sitting not started. 12.23
    Volts across batt when running 14.5
    Volts acorrdding to voltmeter in truck about 10 when truck is running.. Sometimes will go to 14 and sometimes to 8 depending on turning stuff on or off.. see above post.
    Volts according to voltmeter in truck when ing key is turned to on but not started 8.

    I replaced the alt and starter solenoid with no change in the symptoms. I'll be getting and trying the ignition switch today or tonight hopefully.

    I ran another ground from the Neg batt post to the body and also ran a separate ground from the block to the body since I could not see to verify the condition of the rear ground strap condition.

    All the wires I have looked at seem to be n good condition and I've cleaned up what I have looked at or had to remove during the above changes.

    Does anybody have any other additional thoughts on what to look for? Right now my eggs are all in the ignition switch basket.


    Oh.. And yes, when I run windows or accessories ( air compressor etc) with the jey off, it draws the gauge right down to 8 when it is acting up. Other times, it works fine.)

    Damn intermittent electrical is a killer.
    Thanks again,
    Brett
    Allright, I just replaced the ignition switch and the spymtom is the same. Right now, It will not start at all. I hooked up another battery and the symptom is the same.

    Does anybody have the pin out and voltages I should be seeing in an 88 blazer at the ignition box? I have no idea where to go at this point. Any help would be really appreciated.

    Brett
     
    Last edited by a moderator: May 10, 2006
  2. AZ79K5Project

    AZ79K5Project 1/2 ton status

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    I had a similar problem. It turned out that the grounding strap from the engine to the frame and engine to body were missing. The engine to body was actually broken. I put one in from the engine to frame just as a second strap.

    Your grounding straps my be rusted at the bolts and losing contact as well.

    It cured all my problems. Same type of issues.
     
  3. readymix

    readymix 3/4 ton status

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    It does sound like a ground issue too me since you are getting good readings at the battery with the DVM.
     
  4. bnc04

    bnc04 Guest

    All grounds are there and in good shape cable wise. I took the grounds off at the frame and body and ground down to bare metal just to make sure that they were making good contact. I could not verify the woven strap connection at the passanger side block location so I ran a seprate grond strap from the Alt Mounting bracket to the body. I also ran a ground wire 2 guage from the neg batt terminal to the body as a precaution.
    I really thought it was a flaky ground also but I can't see where that is the case anymore. I'll keep looking though. I'm going to replace all the Batt power cables to the starter and will trace to te alt and replace those as well.
    Thnaks for the advide, keep it coming!!!
    Brett
     
  5. readymix

    readymix 3/4 ton status

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    even the one behind the pass side head?
     
  6. bnc04

    bnc04 Guest

    No, I could not reach that one so I created another one from the engine block to the body using 2guage battery cable wire.
     
  7. readymix

    readymix 3/4 ton status

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    Sounds like you got the ground good.

    Could be the ignition switch.
     
  8. broke73

    broke73 1/2 ton status

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    You might have any intermitent short between ground and Positive. Pull off your battery leads and check the continuity between them. It should be pretty high like 20 mega ohms. I would check the big cable going to the starter and the alternator. Maybe the one for the starter got to close to the exhaust.
     
  9. bnc04

    bnc04 Guest

    Now I'm getting Pissed

    After replacing the ignition switch with the same symptom I went though and replaced the both battery cables with brand new ones and new connectors on each end. I ran the + to the starter and the alt. I also rechecked the connects at the new solenoid. Ran the - cable and added star washers and verified every ground had good contact. It started right up, when I operated things there was minimal draw and it looked like I had it whipped so I cleaned up the tools and took a shower, Came out for a test drive. No start again, after several tries it started and is acting the same way, Intermittently loads will cause it to drop voltage rather significantly ( 14-9) or so. An example, If I turn the blower motor on, it may drop,, or it may not,, If it drops, I tap the brake pedal a few times, and sometimes I can get it back up to 13-14 volts on the voltmeter.

    WTF is going on?
    Thanks again for all you advice,
    Brett
     
  10. bnc04

    bnc04 Guest

    Sorry for all the posts, I’m not too good of a mechanic but I try and think about things in a logical manner, Which, not understanding how the electrical system works and not being very fluent in Multi meters makes it tough.

    Is there a possibility that a short or corroded wire that runs from the starter back to the connector at the alt and then to the hot post of the alt be causing this? It sure seems like it is a regulator issue in that it happens when I drive, when I am stationary, and at odd times which is caused by adding a load to the system. Once I get it running, anything from a blinker, to using the brakes, to turning on the radio or activation the heater/air blower motor can cause the volts to drop ( according to the gauge in the dash.. When this happens,, sometimes I can activate another item to create a load and it will bounce back…

    I guess maybe it is time to start cutting up the wire looms and tracing all these wires back to the firewall and look for anything that is apparent..

    One other thing,, I do have a b/m auto shifter on the console. I have the collar on the steering column wire tied to the left. Should I short the neutral safety switch to something and make sure that is out of the loop also? I can’t see how this would cause the scenario with the loads but I’m at my limited wits end..

    About ready to invite whomever over and provide all the beer they want to diagnose this thing!

    Thanks again for listening
    Brett
     
  11. bp71k5

    bp71k5 3/4 ton status Premium Member

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    I had similar trouble in another car, and it was the battery. If the battery doesn't have enough charge, it can still run the lights, but when you try and start it, there isn't enough juice to engage the solenoid and so it just spins and sounds like a bad starter. Try swapping batteries and see if it helps. If not, the startern (actually the solenoid) is probably going bad.
     
  12. bnc04

    bnc04 Guest

    Already replaced the starter solenoid, Alternator and ignition switch. Would a Batt sometimes fire right up no problem and others, no click at all? Sometimes when I turn the key and get no start, I back off turn it back off, turn it,, and it will start after a few of these repeats.
    I guess I can try a new Batt, whats another 60 bucks. LOL.. I'd really like to try and diagnose it before dumping more money into it.
    Brett
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    Just reading the last post, when it won't start, do you notice any other problems electrically?

    Wondering if you've got a flakey fusible link.
     
  14. bnc04

    bnc04 Guest

    When I jhave the no start condition, the elictrical items seem to work ok but at reduced capacity, like the windows are slower going up and down, thats the only thing I can tell, The check engine and brake idiot lights come on as they should. I'll recreate and pay more attention in that areana and edit this post,
    Thanks Brett
     
  15. mouse

    mouse 1/2 ton status

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    I noticed that you put in an after market shifter, and since replacing the ignition switch it doesn't start. Try tracing the park/neutral safety switch and make sure its not the cause.
     
  16. jamber2541

    jamber2541 1/2 ton status

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    Did you ever find the problem??
     
  17. bnc04

    bnc04 Guest

    I think I may have. Since I have the engine , body and frame very well grounded together, another person mentioned that there may need to be a ground to the dash to tie into the other grounds. I made one up and tied the firewall to the dash and after a few days, the problem has not re-occured. So,, Hopefully thats it.. Now It has started to stumble badly at times between 1200-2200 rpms with a lower than normal idle ( 500-600rpm) I just replaced the fuel filter and am running injector cleaner through it. My back is whacked so I will have to wait before inspecting the hoses for vac leaks etc.
    Brett
     
  18. opfor2

    opfor2 1/2 ton status

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    Did you by chance check or put a heavy ground wire from the Eng. block to the frame? I just did this to my 90 Blazer and it seemed to smoothed out my idle problem. (at least it sounds smoother, only time will tell)

    Dan..
     

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