'97 GMC Sonoma/S15, codes tranny issues?

[RoadWarrior222]

Hi folks,

Well my brother in law is having some trouble with his GMC compact truck, not sure whether it's a sonoma or just S15 or something. I've just talked to him quick on the phone about it, he was just home for an hour then had to go off and haul freight again, (Not in that ) and he's not home much, so this will probably go slow.

Anyway, as far as I could gather, it's in some kind of limp mode with CEL lit, and he says the tranny is "Stuck in overdrive" I guess he might mean it's stuck in 2nd or 3rd, too high a gear to set off in, or maybe it's just slipping so much that that's what it feels like. It's the 4.3 V6 with whatever tranny normally goes behind it.

He/we can't seem to figure how to get the codes off it yet. I though there was some keydance and hooking a light up to the diagnostic connector possible on these, but that might have been in the OBD1 era... my reference materials are too old. So will an OBD2 scanner help him out much? Or is there another way to pull codes?

Also from the crappy description so far, does it sound like any common problem? What might we want/need to dig into?

thanks,

RW222

---------- Post added at 10:05 AM ---------- Previous post was at 09:57 AM ----------

Okay, looking at this, I'm gonna take a wild guess and think maybe his 1-2 solenoid has failed...

http://en.wikipedia.org/wiki/GM_4L60-E_transmission

does that sound likely?

[Big_P]

Could be a sticky valve body but probably not, I've seen a few GM trucks get stuck in 3rd, they all get sent to the rebuilder after that

---------- Post added at 03:21 PM ---------- Previous post was at 03:20 PM ----------

An OBD2 scanner MAY work. Depends what you have. If you have an Autozone code reader probably not, but something like a Genisys would pick up the code for sure. Still worth a shot either way.

[turbovanman²]

You can't flash the codes, you need a scanner. GM's fail safe mode is 2nd gear only, so it could be anything, TPS, shift solenoid etc. Post up after he gets the codes. Those 4L60E's are pretty stout, the only real issue is the sun shell shearing off and IIRC, you get 1 and 3 only, or its 2 and 4.

I've got 220K on my 98 Jimmy and I haven't been nice to it, the front pump leaks but that's typical with the mileage as the bushing spins. I need to get it out and freshen it up, its been an awesome ride,

[RoadWarrior222]

Well he managed so far to drive it back home from his truck depot, and confirmed that it's only getting second and 3rd gear, it seems to drive okay for 10 mins or so, then gets warm or something, puts the light on, then it's only 2 and 3 ...

He was gonna call me to go over today, but I guess he picked up another run.

I hear of these 4L60Es getting problems more when in Roadmasters or full size trucks with V8s due to towing (Like 5000lbs or more worth) , but he put the bar on this when he got it last year, and hasn't moved anything heavier than a popup camper. So don't think it's really had a "hard" life so far.

Is there such a thing as a "good" low end scanner? he's got a 2001 Windstar as well that he'd probably want to use it on if he bought one.

[Big_P]

I have this: http://www.facebook.com/note.php?note_id=433861958642 I don't know why it's a facebook page, I googled "Blue point microscan" and thats what I found lol. I think I paid $300 for it. It does live datastream and ABS codes as well.

It's a good tool but I really miss the Genisys I had. You can get a used Genisys for probably 3-400 bucks with dated software (still an excellent tool though)

[RoadWarrior222]

Just heard more...

He took to in to a place that did a free code read, but the CEL didn't come on, on the way there, and their scanner didn't find a stored code, then he drove it back again and on the way home it came on and got stuck in 2 and 3 again...

Hum, by the way, could this be the shifter switch screwing up? Dunno how it is on this, but when I first got my Escort it could only get certain gears due to damage to the shifter switch, that was a no-code issue for that but that is on a pre OBD-II ecu.

Since it might just be dirt/gum sticking up the solenoids or something, he's gonna try sticking some lucas in it for now, see if it behaves better.

[black86glhs]

It needs to be run with scanner on it to see if it can be manually shifted or see trans codes. The PRNDL(the technician term for the selector switch on the trans) can also be verified as good or bad. As long as it is taken to someone knowledgeable, pay the hour diagnosis fee and then go home and fix it.
It may just be a bad valvebody and need replaced.
How many miles and has the fluid and filter ever been changed?
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[Big_P]

It needs to be run with scanner on it to see if it can be manually shifted or see trans codes. The PRNDL(the technician term for the selector switch on the trans)

Ah yes, the ole' "Prindle"!

[turbovanman²]

Bad valve body's???? New one to me,

I bet he didn't check the history codes, anytime the light comes on, it will set a code.

I haven't messed with it too much yet but picked up Innovates OBD2 adapter, works awesome with my iPhone,

[black86glhs]

If the fluid is old and skinny, I have seen a couple where the VB needed to be pulled and cleaned. That is what I was referring to, not bad ones.

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