'03 Suburban 2500: CEL and Xfer case selector weirdness.

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by cmjust0, Feb 11, 2009.

  1. cmjust0

    cmjust0 New Member

    Lately, I've been noticing that the transfer case selector will show the wrong selection at startup. I'll park the vehicle in 2Hi, but when I restart, it'll show either neutral or 4Lo (neutral is more frequent). Thing is, I've driven it before noticing that the display was incorrect, and the vehicle was indeed in 2Hi just like I left it, regardless of what's lit up. I mean, if the transfer case were actually in neutral, for instance, it wouldn't go anywhere...and you'd definitely notice 4Lo at highway speeds..

    To get it to display 2Hi, I have to put the transmission in neutral before selecting 2Hi. If I leave it in Park or any other gear and try to select 2Hi, the 2Hi light will blink for about 10 seconds before giving up.

    Going from a transfer case display of Neutral to 2Hi is quick and quiet when the transmission is in neutral...switches right over. It's much more worrisome when it thinks it's in 4Lo, because when you put the transmission in Neutral and select 2Hi, it takes a few seconds then you get a pretty solid CLANK from the undercarriage before it switches. That clank scares me. Deeply. Afterall, the vehicle's not actually in 4Lo...it's in 2Hi...switching to 2Hi...what's there to clank?

    Anybody ever seen a problem like this before?

    Also, I have a check engine light issue. Seems to be independent of the transfer case stuff, because they don't necessarily happen at the same time...in fact, I don't think I've ever seen them happen at the same time.

    Anyway, I'll start the vehicle and the CEL will come on..then chimes..then a "REDUCED ENGINE POWER" message. If I try to drive it like that, it won't exceed 2K RPM...'limp in' mode. If I shut it off and restart, the CEL will stay on but the message goes away and the vehicle is back to full power. Typically, If I shut it off and restart once more, the CEL and message are both cleared and it's as if nothing ever happened.

    Anybody got a clue about what might be causing that?

    Thx in advance!
  2. Springthing

    Springthing Epic Member 5+ Years 1000 Posts

    As for the CEL... it will need to get codes checked. Sounds like there is an issue there somewhere when the car sits for a little bit. The reason, I'm guessing, that the problem 'fixes' itself is because you are cycling the engine on/off. Most times the CEL will turn off after a certain amount of cycling without having the issue it recognized previously. So, hypothetically, if you have something faulty that has to do with temperature... when you first start the truck up the truck will notice the fault and flick on the CEL. Once the truck gets turned off and then back on, the fault will not occur and so the truck takes note of it. If you cycle it once more the truck will notice the fault is gone still, notice it's already found the fault to be absent once before, and so the problem must be cleared up... so it turns the CEL off.

    I think that's right.. :)

    But I'd have codes checked to see what the issue is. Even though the CEL is off the codes are stored.

    The transfer case... is way WAY above my head!

    We have some good folks here - hopefully they'll be able to tell you what to look for and/or what might be the problem.

    Good luck,
    Last edited: Feb 11, 2009

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