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  1. #1

    Angry 02 Silverado: Flashing service light, wont shift from 1st to 2nd????


    My name is Thom, Im 20 years old, just joined this forum. Seems to be the best out there! Anyways, now on to my problem...

    I own an 02 silverado z71 extended cab. My truck has 160,000 miles on it. I have taken good care of it. I recently had a problem tho, when i would tack it out my service engine soon light starts flashing. It doesnt stay on tho, it always turns off after i just drive it normal. I had my mechanic check it out showed misses on 6 of the 8 cylinders. i figured at 160,000, it was pry due for a fuel pump, especially cuz it has been dogging when it get to the end of first gear.(seems like it took forever for it to shift to 2nd) My mechanic concurred. So I replaced the fuel pump today, and not only did that not fix the problem, but its worse now than it was before. Now, instead of taking forever to shift from first to second, it wouldnt shift at all from 1st to 2nd gear. And yes, the service engine soon light began to flash. It even flashed when it had to go up a hill on the interstate and dropped to 3rd gear. It never did that one before either. WTF do I look for next?? Heres what I have done that I am almost positive cant be....

    Replaced Fuel Pump and Fuel Filter, checked plugs and wires (seemed fine), recently had transmission flushed (the guy before me regularly had it flushed, have all the service records)

    Sorry this was a bit in depth, im just stumped

  2. #2


    could be your coils, has it been in a lot of water beofre?

  3. #3


    other than rain, no not really my engine is more open to the elements though. i have a 3 inch body lift and i can see through the wheel wells to my headers. ive been meaning to get gap guards for it

  4. #4


    i am very unsure of the cause,

    are you SURE the plugs are good?

    2002 Jeep Wrangler Sport 4x4 (the Yellow Jacket)
    4inch suspension 3inch body
    Straight 6 (383 Stroker within a year)
    36inch SuperSwamper TSL.
    Detroit Loccers
    Daily Driver Weekend Wheeler
    much more...

    2004 Sierra crew cab, 2wd, 5.3 V8
    2inch Daystar Leveling kit
    single dumped Flowmaster 40 sieries exaust(removed)
    Mb Blitz Chrome wheels
    Leer Bed Cover(for sale)
    50k miles

  5. #5
    Sr. Apprentice browenb's Avatar
    Join Date
    Apr 2008
    Saint John, New Brunswick, Canada


    The flashing Service Engine soon light happens because of the RPM's your running your engine up to. If you look at your oil pressure gauge while driving at higher rpm, it makes the service engine soon light flash. (It wants to to look at your gauge cluster to see that the oil presure is way too high.

    You said you changed the fuel pump and filter. And the Wires and Plugs 'seemed' fine. Did you have your friend check with the conputer again to see if the misses are still happening?

    Have you reset your computer. (unpluging the batery for about 10 to 15 minutes should do it)
    Fior example, I was being a goofball one day while running a power line for a guy's stereo, I think it was an 04 silverado. Anyway, there was a plug on the firewall in the way, so instead of disconecting the batery terminal, I just went ahead and unpluged the cable. Turns out it was the cable for the air bags. They didn't go off, but they did throw a warning, that I couldn't get off, even after reconnecting the cable. Only way I fixed that problem was to take the batery terminal off for about 30 minutes (lunch) and hook it back up.

    Your truck might still think there's still a miss in those cylinders, and is perposely not sending fuel...

    I am, of course, NOT a technician, just giving my 2 cents worth. And I do appologise if this is too simple, as I obviously have no idea what your personal skill set is.

    Best of Luck.
    '04 Silverado Z71 Special Edition
    '81 Camaro - 400 SBC - 30 Over - th350 w/Stage II shifter - 4.10's
    '70.5 Camaro - Bone Stock

    '75 Porsche 914
    '27 Model T

  6. #6


    I think that resetting your computer is a good place to start. Then if it throws a code again you will know to look deeper. Seems to me that your throttle position sensor could be having fits as well. That is just a guess though. Another good thing to do is run a bottle of good fuel system cleaner threw it if you already haven't.
    Mike - OREGON

    2001 chevy silverado 4x4. 5.3L, 6 inch Fabtech lift, 35" Toyo MT's, 17" Weld Racing wheels, arma coating on rocker panels. No exhaust after cat. Pioneer stereo

  7. #7


    welp it was my damn catalytic converters they were both plugged up had them removed truck is runnin like a champ again thank you everyone for your input!

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