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  1. #1

    Default Need some big time help!

    I need some big help here with my 2000 Silverado, I was driving on the highway on cruise control then the gauges went all haywire and the ecm 1 fuse blew,Now the truck starts up but has a sercuity light on,abs,air bag,no fuel gauge,no temp and when its running will not show me what gear im in.However the gear indicator works when its not running just running it doesn't show which gear your in.I would love to know where all the grounds are.Also what would cause the ecm fuse to blow?i understand the ecm 1 fuse controls the fuel injectors and crank sensor and such.But it runs fine.Please any help would be great thank you!

  2. #2
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    Quote Originally Posted by lsxmotors View Post
    I need some big help here with my 2000 Silverado, I was driving on the highway on cruise control then the gauges went all haywire and the ecm 1 fuse blew,Now the truck starts up but has a sercuity light on,abs,air bag,no fuel gauge,no temp and when its running will not show me what gear im in.However the gear indicator works when its not running just running it doesn't show which gear your in.I would love to know where all the grounds are.Also what would cause the ecm fuse to blow?i understand the ecm 1 fuse controls the fuel injectors and crank sensor and such.But it runs fine.Please any help would be great thank you!
    what is the vehicle history ? work done ? how long YOU owned this vehicle ?

    you have any aftermarket gizmos on there ?

  3. #3

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    I bought it off a guy that had a amp hooked up,and a remote start.i took all of that stuff out.I just got it back from the dealership they couldn't find anything.I have own the truck for about 4 months.btw im getting a p1639 code when the truck shutted off and blew the ecm 1 fuse.

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    it seems like everything got worse when this truck was towed.I have a push button 4wd and the trans far case is always locked up from what it says under the hood they should of atleast disconnected the front driveshaft.

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    also when the truck is running the security light and battery light are on.

  4. #4

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    Quote Originally Posted by lsxmotors View Post
    I bought it off a guy that had a amp hooked up,and a remote start.i took all of that stuff out.I just got it back from the dealership they couldn't find anything.I have own the truck for about 4 months.btw im getting a p1639 code when the truck shutted off and blew the ecm 1 fuse.


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    it seems like everything got worse when this truck was towed.I have a push button 4wd and the trans far case is always locked up from what it says under the hood they should of atleast disconnected the front driveshaft.

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    also when the truck is running the security light and battery light are on.
    The NP246 transfer case normally turns the front driveshaft, but that does not mean it is locked- there is no power going to it unless it's engaged in 4wd.
    Sounds to me like between the previous owner adding the remote start and hooking up the amp, then you removing caused some type of electrical gremlin. I doubt a tow would be causing the issues that you're describing.
    Electrical stuff is what I know the least about, so I'm no help there.
    Current Rides: |99 Chevy Suburban- the family truckster |93 Lincoln Town Car- 250K miles & still churning -now a fan of the Panther platform |95 BMW 325is coupe- Wheeee!
    Former GM cars: |78 Suburban 454 |71 Buick Electra 225 (deuce & a quarter) |75 Monte Carlo- 400SB- heaviest doors GM every made |70 Impala coupe- my 1st car

  5. #5
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    now I find it very interesting that the dealership found nothing . what about the 1639 code ? did they comment on that ? also where did you get that info on the ecm 1 fuse as to what it feeds ?


    the ecm 1 fuse is power to the PCM/computer module....

    the 1639 code is a 5 volt DC feed created inside the PCM if that voltage is not correct the code will show.

    this 5 volt dc voltage with this code goes to the fuel tank level sensor and the throttle position sensor.

    the dealership should have removed the PCM and inspected the connectors wiring to from the fuse box . remove the fuse box under hood next to the PCM and see what wires if any had been damaged, many with these type problems have found rodent chewed up wires.

    my advice to you is you do not bring in a vehicle this old to the dealership . the reason they did not fix it is because it is not a money maker . they want you to buy a new vehicle .

    so I guess you will have to find a repair shop with the proper wiring diagrams to track down the wire / and or component short or whatever blew the fuse.

    the fuel tank fuel pump assy is a complete pkg. pump/sender unit. if this was replaced many mechanics half azz the wiring where the new connector is spliced into the OEM wiring harness at the top of the fuel tank. if you do this troubleshooting make sure those wires are soldered and the use of heat shrink is used to connect/seal these electrical splicing connections.

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  7. #6

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    Update* tried installing a new ign switch disconnected battery now the truck will start and stall instantly like it has security issues but the security cycles from the battery light,back to the security light.Its not on steady.This problem only occurs when the battery is disconnected for little while.The truck has a brand new airtex fuel pump/sending unit.the connectors going to the fuel pump are fine and are correct.

  8. #7
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    Quote Originally Posted by lsxmotors View Post
    Update* tried installing a new ign switch disconnected battery now the truck will start and stall instantly like it has security issues but the security cycles from the battery light,back to the security light.Its not on steady.This problem only occurs when the battery is disconnected for little while.The truck has a brand new airtex fuel pump/sending unit.the connectors going to the fuel pump are fine and are correct.

    well another vehicle owner with an airtex pump. these are at best good for 1 year. most die in 3 months.

    if you screwed with the ignition switch lock cylinder or did not disconnect the battery ground before working this the security may be messed up or need be reset. there is a procedure for the reset of the key/security ..

  9. #8

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    I have an airtex in my 99 sierra had it for over 2 years no problems at all.I got it back from a 2nd dealer today they could that the ground by the fuel pump was very rusty and that the bcm had lose connections.The bad fuel pump ground caused the bcm to lose data line to the other modules causing it to start and stall.Still have gauge problems I think that's related to a bad cluster though.

  10. #9
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    Quote Originally Posted by lsxmotors View Post
    I have an airtex in my 99 sierra had it for over 2 years no problems at all.I got it back from a 2nd dealer today they could that the ground by the fuel pump was very rusty and that the bcm had lose connections.The bad fuel pump ground caused the bcm to lose data line to the other modules causing it to start and stall.Still have gauge problems I think that's related to a bad cluster though.
    the bad fuel pump ground causes the fuel pump to not operate. dash cluster has nothing to do with the fuel pump. fuel pump is controlled by the PCM.

    mechanics doing electrical work with out the proper training is most likely the issue . many have had fuel pump failures related to improper wiring splicing at the fuel pump. wires need be soldered and heat shrink to seal and make a low resistance connection in a corrosive environment.

    your having an airtex pump installed by a dealer is this a GM dealer ? I have heard of GM dealerships using cheapo parts to enhance the bottom line.

    you have been on these forums long enough to know many on here do not recommend airtex..

    I would check fuel pressures do the fuel pressure testing a few times when it acts up.

  11. #10

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    thanks for your reply,Just for an update the cluster works if the truck sit over night then after about 30 secs on it running the gas gauge and temp gauge also the gear indicator go dead.

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