Service Engine Soon Light

[MSSM]

(this is the wife here).....

My husband is out of the country right now. I went to pick the kids up tonight from a basketball game at school. So, since I haven't driven his truck in a couple of days I was going to drive his truck tonight. It's cold outside (about 40), so I went out to warm up the dmax. I let it warm up for about 10 minutes before I left. I got in and the service engine light was on. (few choice words) I put it in reverse and it wouldn't go anywhere, I put it in drive, wouldn't go anywhere, did the reverse again, still nothing. I turned it off, let it sit a few minutes and started it up again. Same thing. Nothing....(more choice words). I go hop in my truck and warm it up. As I'm driving off, I said to myself that I was going to try his truck again. I hop in put it in reverse and it backs up, put it in drive, it goes forward. Light was still on though. I still take my truck to get the kids. I got home and tried it again, light still on, but it's still going in reverse and drive.

Last week before my husband left I was in town in his truck. I was leaving the store I put the truck in reverse and backed up. I then put it into drive, I waited till I felt it shift gears and I start to drive forward. Well, when I took off it like lunged backwards, felt like 3 times(I was in drive). I told my husband about it and he thought that maybe I wasn't actually completely in drive. Truck drove fine and didn't have the problem again. I drove it over the weekend and was still fine.

Any suggestions on what could be the problem??.....I've called and left a message for my husband to call me when he gets in from work, but it's going to be like 3am here before he calls. He's in Guam and they are 16 hours ahead of us.

[ 11-26-2002: Message edited by: MSSM ]</p>

[TxDoc]

I do not know your answer, but feel sure you will get the needed help.

I just posted to give you kudos for making the post and being so concise with your description of the problem.

[MSSM]

Thanks for the complement.....Were you serious though? Or was that a tackful way of telling me I babbled too much...... :D

[TxDoc]

Was not being facetious. Many women (and men) tell you, "it goes whoosh, whoosh, clickety-click, bang, zing."


I think the folks on this board have either experrienced every conceivable problem or know someone who has. Thus, they will be able to take a good description--which you gave a great one--and tell you what the actual problem is, and what the probable solution should be.

Being "The Mom" is hard enough, nowadays, and being able to handle the family stuff AND the problems that arise, like the truck, compound the difficulty. So--"you did well" :)

[MSSM]

Thanks again. I was just giving you a hard time with my last post.

That's one thing about me, I have so many things on my plate to deal with and having to be both the man and the women, I have to be able explain myself well when dealing with stuff like this. That way when I go to the shop or any place else for that matter, I don't get treated like a women and get screwed over.

My husband has been gone less then a week and all hell has broke loose around here. First our daughter fell in a campfire at a girl scout campout over the weekend and got 2nd degree burns and then this with the truck.

[SoMnDMAX]

Mrs. MSSM,

Very good job describing the problem with your truck. As TxDoc said, Kudos!!

Sorry to hear about your daughter. Hopefully the recovery is quick!!

Onto the problem at hand... Sounds like torque convertor drain down. Not a huge issue, just a quirk with the Allison transmission. If you don't know what the torque converter is, I'll keep it as basic as possible- it's the apparatus that transfers power from the engine to the transmission. It serves a similar purpose the clutch does in a manual equipped vehicle, only a torque converter uses hydraulic principals instead of friction.

Below is a post from a while back containing an excellent description of what happens when the torque converter drains down. Scroll about half way down, and pay particular attention to the posts from Big Al. You'll need to copy and paste the URL into your browser.

http://forum.62-65-dieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=7&t=003020&p=

Hope this helps.... Feel free to post back if you have any questions!!

Matt

[MSSM]

Thanks!! Tomorrow when I'm not soooo tired I'm going to sit down and read the entire thread, but I skimmed though it and I read what I wanted to see (that it's probably not going to cost me several thousand dollars like I figured...) Now I can sleep!!!

My husband actually called early tonight and I told him the problem. He didn't seem too concerned and told me to go drive it tomorrow and see what happens.

Thanks guys, y'all are wonderful!

[MSSM]

OH, BTW and I promise, I let the truck warm up for 10 minutes before I tried to take off in it. LOL I've been told to NEVER just, jump in and throw her into gear. That would be grounds for divorce around here. I've been known to do that to my truck (it's a gas truck. But I don't do it often, I always let my truck warm up).

[MSSM]

I read the other thread and I think I understood pretty much what heppend. I drove the truck and it ran fine. I checked the transmission fluid just to make sure it was ok. It was fine. Now, will the SES light go off or am I going to have to take it anyway so the light can be reset?

[mdrag]

Mrs. MSSM,

If the problem was torque converter drain down and it does not happen within so many ignition cycles - the SES SHOULD go off by itself. The DTC (diagnostic trouble code) will be stored in the ECM. How many ignition cycles for the SES to turn off depends on the particular DTC - I've read that as many as 40 ignition cycles for some DTCs...

If it's not the torque convertor drain down problem, another POSSIBILITY could be the NSBU or neutral start back up switch (or PNP switch in Chevy's terms - park neutral position). The NSBU switch failure usually causes the tranny to go into limp mode, and some/all of the letters/numbers on the gear selector display 'disappear'. I'd bet on the draindown problem as most likely.

Good luck. I hope your daughter has a speedy and uneventful recovery.

[SID6FIVE]

In all likelihood the problem is with the NSBU switch on the side of the transmission...the Allison tranny is all electronically controlled, so if the NSBU switch is not working you only get neutral.One way to tell if this is the problem is if the square highlight around the indicated gear flashes or is missing entirely...up here in the great frozen north we have seen many of these fail...part has been updated at least once...replaced more of these than I can remember...good luck!