I'm looking to buy a truck to act as my daily driver and as a winter car and I found a GMC sierra 1500 for a decent price and aside from some body damage which I don't care about the only problem seems to be that the car is stuck in 4 wheel drive. It is an automatic and I was wondering if anyone is familiar with this problem?

Is this an easy enough fix or with this end up being a money pit?

Thanks

It could be as simple as the actuator in the frt axel is stuck in the 4x4 mode. Hard to tell without a little more info.

Year?
Model?
Type of 4 wheel drive system? elec?
Steve

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Technology is great when it works,
and one big pain in the ass when it doesn't.
Detroit iron rules all the rest are just toys.

1997 GMC Sierra 1500

I don't have any more info, the guy said it was the actuator but I know nothing about 4 wheel drive systems and it is hard to believe the guy because he is the one selling the car so of course he is going to say it is an easy fix.

If it isn't the actuator what else could it be and how hard/expensive is it to fix?

I had the opposite problem once - Dakota was hard to get INTO 4 wheel drive. (I could but it too some effort)

One thing to keep in mind, how long has it been stuck, and has he driven it long in that condition (maybe he drove it too fast or whatever) for a while while in that state)

You may be able to get it out of 4 wheel drive, but not be able to get it back into it again,(or it might cost a lot to repair it) whould you still want it if it was only 2 wheel drive? Sorry, I don't know much about this stuff, but I DO know sometimes, people will abuse their vehicle and try to dump it on someone...

its most liklely the vacuum actuator OR it could be one of the vac lines from the actuator. Had the same problem with my Burban awhile back and just used some vaccum tubing i had laying around. If you get to look at it check the front axle for the lines coming off of it, if they look old or crusty they need to be replaced of say goodbye to any sense of good gas mileage

The actuator, if I am not mistaken, locks in the front hubs. But, it needs direction to do so. As Ramsespride said, it could be vacuum operated and be a vacuum problem or a bad actuator.
However, I can drive around all day long with my front hubs locked in and not be in four wheel drive mode because my transfer case is in two wheel drive mode. My Jeep CJ7 has manual hubs and a manual shift lever. My Tacoma 4X4 has a dash on the fly switch which shifts the transfer case into 4WD and also locks the hubs. I think (?) it is an electrical switch. So, you could have a bad actuator, bad vacuum lines, or a bad switch. It could also be the shift rod in the transfer case is bound up from mudding and/or that actuator might be bad (thinking about the theory, there must be different actuators).
Are you sure it is locked in 4WD or is the 4WD indicator light just staying on ? A quick test would be to drive while turning in a full lock. The rolling momentum will be strained because it is not an open or limited slip differential. You could also unhook the rear drive shaft and see if the front wheels will move the truck.
I don't know that truck nor the system that it uses. An electric actuator on the transfer case, it could be a wire, a fuse, or a faulty actuator. Vacuum controlled, it could be a vacuum line or maybe a bad diaphram in the actual actuator body.
As far as your question of if it might be a money pit, yes, it very well might be. 4WD work for whatever reason seems to be pricey, but it really is simple. As 84fiero123 says, we need more info. We can walk you through it but we do not want to fix it for the seller. Tell us more about the truck. How much ? Another thought. Any vehicle that one buys, he should have checked out by a knowledgeable mechanic. Many times you can tell the seller that you will pay for this check and if you buy it he will deduct the cost from the sale price.
Hmmm ....

It depends on if it has the electronically shifted transfer case or the mechanical handle. Either unit has the actuator in the front differential, but the mechanical handle one shifts the transfer case mechanically (duh) and the electronic one does it through an actuator on the transfer case. Easy way to tell is does it have a handle on the floor or buttons/knob on the dash? If it's the handle on the floor about the only thing it can be is the front actuator motor not disengaging. The last one I put in I think cost about $100. Now if it's the actuator on the transfer case, it could be a couple of things. Either the actuator itself, pretty pricy and not much fun to change, or it could also be the switch setup on the dash, easier to change and about $80, the last time I put one in. The switches on the dash are a common issue and most dealers will have them in stock. Very simple to put in, pull the bezel out, a couple of screws, swap the switch, back together.

John Stricker

quote Originally posted by McCool: 1997 GMC Sierra 1500 I don't have any more info, the guy said it was the actuator but I know nothing about 4 wheel drive systems and it is hard to believe the guy because he is the one selling the car so of course he is going to say it is an easy fix. If it isn't the actuator what else could it be and how hard/expensive is it to fix?

I think the 97's have an electric actuator motor. There might be some push/pull cable actuated ones. If electric then unplug the motor and do standard electrical troubleshooting such as check if it gets power, check if it gets a signal when the button is pressed or not, etc. If it is just a cable, then likely the cable just broke.

quote Originally posted by Doug85GT: I think the 97's have an electric actuator motor. There might be some push/pull cable actuated ones. If electric then unplug the motor and do standard electrical troubleshooting such as check if it gets power, check if it gets a signal when the button is pressed or not, etc. If it is just a cable, then likely the cable just broke.

they are i just looked at buying a 97 burban for body parts for our 94 and it is electric. so i agree with that.

steve

------------------
Technology is great when it works,
and one big pain in the ass when it doesn't.
Detroit iron rules all the rest are just toys.

Not all '97's were electric. You could get them with the handle and mechanical shift but the electric shift began being offered in '96 and as time went on especially in the 1/2 line it became more common to have buttons to shift the transfer case and less common to have a floor mounted lever.

If it doesn't have a lever on the floor, it's electronic controlled.

It is probably NOT the front axle actuator. The went away from the thermal version a couple of years before and the later ones were more reliable. Besides, as I read the post it seems it's not shifting the transfer case out of 4WD and the front actuator has nothing to do with that.

As I said before, it's down to a couple of things. First the switch. If it has the rotary switch that's probablynot it, they're pretty reliable. If it has the push buttons then it could very well be that and it's not too expensive to fix that. If it's not the switch, it's the actuating control system itself. That includes the actual motor, or encoder, as GM calls it, down on the transfer case or the transfer case control module mounted under the dash. To find out which one you need to pull the codes and probably go through the diagnostics to see what's up. Both of these two are a couple hundred dollars plus from GM so you don't really want to guess wrong on them.

Don't forget to check ALL the connections to the tranny/transfer and remember to check all of the grounds, without them the encoder won't shift properly.

John Stricker

quote Originally posted by Doug85GT: I think the 97's have an electric actuator motor. There might be some push/pull cable actuated ones. If electric then unplug the motor and do standard electrical troubleshooting such as check if it gets power, check if it gets a signal when the button is pressed or not, etc. If it is just a cable, then likely the cable just broke.

My '97 Chevy Blazer had similar ills a couple years ago.

The encoder motor that shifts my NP233C transfer case, locked up in 4 HI.
Took the front driveshaft off, until I could find the problem.
Local GM dealer quoted me $1108.00 for a new encoder. Ouch.
Found a wrecker in Calgary, that sold me a used one with a 90 day warranty, for $200.00 .

Also discovered there are two different fuses, that control the encoder.
The dash buttons would flash, but still would not shift.

Check both fuses. Might be that simple.

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Marko.

'85 SE 2M6
Original White paint, with Sunroof
3.65 M17 4 speed = F.U.N. in the Sun.
Whoo hoo, Spring has sprung

My GM parts books are old but they show the encoder as about $425 list in '05. I'm sure they've gone up, but $1108 seems like a lot.

I just ran a search on one of the online GM Parts places and came up with this note:

Part number 88996604 was superseded by part number 12386247.

The MSRP of that part is $448 and the sale price from them is $294 + Frt. Your Blazer must take a different encoder than a pickup.

John Stricker

quote Originally posted by Marko: My '97 Chevy Blazer had similar ills a couple years ago. The encoder motor that shifts my NP233C transfer case, locked up in 4 HI. Took the front driveshaft off, until I could find the problem. Local GM dealer quoted me $1108.00 for a new encoder. Ouch. Found a wrecker in Calgary, that sold me a used one with a 90 day warranty, for $200.00 . Also discovered there are two different fuses, that control the encoder. The dash buttons would flash, but still would not shift. Check both fuses. Might be that simple.

nope - last 4x4 I had was an 88 Suburban
and - it had the "automatic hubs" which would get stuck
your suppose to put the thing back in 2 wheel mode, then drive in reverse for 10-20 feet, and the hubs would unlock
didnt always happen.
I eventually went and replaced with the classic manual hubs. - worked much better
but - again - GM changed the 4x4 system in later years, and I'm sure this doesnt apply.....

ok here's a little more info:

He drove the car through the winter and never took it out of 4x4. One day the fuel pump broke and the car wouldn't start. After he got the pump professionally installed he tried taking the car out of 4x4 for the first time in a few months and it wouldn't go. Does that help narrow it down? or not really.

Not really, although I think it does point to a mechanical rather than electronic failure. By mechanical, that would include the actual encoder and physical switch, but probably not the control module. The first thing you need to do is get a scanner on there and pull the codes, that would help a lot.

John Stricker

quote Originally posted by McCool: ok here's a little more info: He drove the car through the winter and never took it out of 4x4. One day the fuel pump broke and the car wouldn't start. After he got the pump professionally installed he tried taking the car out of 4x4 for the first time in a few months and it wouldn't go. Does that help narrow it down? or not really.

Well I bought the truck, I figure that even if it stays in 4WD it's better than no truck at all. Anyways... It has the switches on the dashboard to control either 4hi 4lo or 2wd but when you push the button to put the car in either 2 or 4wd they switches do not light up... does that point more towards faulty switches?

I'm probably going to buy a code reader and check to see if it is throwing any codes.

Now i hate to say it but if he had a working 4x4 before the ful pump went and had it replaced at a shop, then there is always the chance that the mechanic cut or did something to the wring to get him to come back and rack up a bigger bill.

ive seen it and "spoken" with a few mechanics in my area that are alittle untrustowrthy about their practices.

quote Originally posted by McCool: Well I bought the truck, I figure that even if it stays in 4WD it's better than no truck at all. Anyways... It has the switches on the dashboard to control either 4hi 4lo or 2wd but when you push the button to put the car in either 2 or 4wd they switches do not light up... does that point more towards faulty switches? I'm probably going to buy a code reader and check to see if it is throwing any codes.

John is right, assuming you have codes, you need to know what those codes are. Surely there is an Auto Parts Store there that will put a scanner on it for you but, if not, then it would be worth your effort to have the vehicle scanned by a mechanic or dealership. That way you'll know where you are, what needs to be done and approximately what it might cost to fix it. At least you'll know whether or not you can drive it like it is or really do need to get it fixed.

Ron

I'm finally looking into buying a OBD2 code reader and searching on the internet I'm finding a lot of different kinds, Is there anything in particular that I should be looking for? and what is a good price for one?