stuck in 3rd

Discussion in 'General Chevy & GM Tech Questions' started by gecko094pat, Jan 10, 2010.

  1. gecko094pat

    gecko094pat New Member

    hey everyone.. new here and looking for some help.

    i have a 2003 silverado hd...8.1 with 5 speed allison transmission with hmm...about 93000 miles on it.
    and it just started acting up. i first notice when i went to put it in park and the doors didn't unlock...but thought nothing about it.. and then when i went to put it into "D"rive the little bar under the selection didn't show up.. so i drove it anyways...goes through first second and into 3rd but not 4th or 5th... sometimes i can pull over...but it into park...shut it off and then start it back up...and it will go up into 4th and 5th...but still no little bar under the "D"rive... i read the DTC's and got........

    po101- mass/volume air flow circ range/perf
    po132-oxy senser circ hi voltage (bank1, sensor2)
    po134-oxy senns circ no activity dectected (bank 1, sensor 2)

    the mass air flow...i would take it would be from the k@n air filter on it...i took it out..put stock air filter in...and tried to clean the maf sensor up with brake cleaner...
    the o2 sensor i bought one for advance under it to but it in.......but for some out of the loop...the only 2 sensors i can find...are on each of the headers..i dont see a second one on the one bank...i found places where they would go..but there isn't anything there but a bolt plugging the hole...

    but the thing is the dtc's aren't that big of a deal...i gotta get this transmission straight...any ideals???

    thanks for the help
  2. unplugged

    unplugged Epic Member 5+ Years 1000 Posts

    Sounds like the transmission is in "limp" mode. Probably your best bet is to get an estimate from a qualified shop.
  3. gecko094pat

    gecko094pat New Member

    still at it..

    still trying to get this solved...i started it up a little while ago...and everything ran just the was it was supposed to run...pulled it to the shop to but the battery on the charger....... looks like a big pill from the gm shop and if no one can come up with any ideals ..????
  4. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Never use brake cleaner on a MAF or MAS sensor, always use sensor safe MAS/MAF cleaner, brake cleaner will leave a residue that can give false readings at best or worse case permanently destroy the sensor.

    Check all the connectors from the transmission for security and water intrusion.

    I just saw a comercial about AAMCO doing free diagnosis on vehicles, might be worth a visit to them for a diagnosis, not sure about a repair from them as I've heard mixed results.
  5. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    If it works OK sometimes and then acts up it's probably the NSBU switch. Keep in mind you need an Allison scan tool to see some transmission codes. If the transmission is stuck in third then there will be codes stored. Also a low battery will cause the NSBU switch to act up. Make sure you have a good fully charged battery.

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