I have a 1997 Grand Cherokee. Side says 'Laredo'. My old cherokee used to be a 4x4, so i'm fairly certain this Jeep is NOT 4x4.

Problem is, the display in the center shows an error message: "Service 4WD Switch". It doesn't go away at all and my mechanic nor the dealer mechanics know what it is. So i'm scratching my head and hoping maybe one of you guys could possibly know what's wrong. Thank you for any help`

i think it has to do with your transfer case i,m pretty sure theres a sensor that acuates the 4wd mechanism crawl under the jeep and see if you see one that may need to be replaced

How do you not know if your own vehicle is 4wd or not?!?

That is one of the "beauties" of owning a ZJ. That message frequently pops up on the VIC's, as well as "Coolant level low" and "Rear hatch open". This comes up very frequently as new owners buy the ZJ, and then get these warnings from the VIC, and wonder if they're new vehicles are going to self-destruct. Nothing will be harmed by driving it.

If you're motivated, the switch itself is located on top of the transfer case, between the front and rear doors on the drivers side. The connection has probably come loose, but you could replace the switch. It's sole purpose is to tell the VIC if you're in 4HI or 4LO.


---How in the world are you getting a message that says "Service 4WD switch" and you don't think your vehicle is 4WD?

I know my Jeep isn't 4x4 because there's no lever to change options like Full time to half time etc.. I'm not a technical guy, I wanted to begin working on my XJ but a rear end collision ruined it.. (It burned to a pulp)

And it's also 2WD. So that's why I think it's not 4WD. Of course i could be wrong and if there's any place or way i could check exactly what it is, it would be helpful. But those are my reasons.

Sorry if it's long, but maybe this might have something to do with it:

We've had this Grand Cherokee since '97, and it's had no mechanical problems. A rear end bent the bumper and broke the catalytic converter. It's got close to 170,000 miles but it runs smooth. Anyways, about two years ago, it was sluggish and turning off almost constantly. I'd be doing 60 on the highway and it would just shut off, and the wheel would lock and it was very hard to turn it towards the side. When it wouldn't turn off, each time i was idle at a light it would be very very close to 0 rpm on the gauge and it would vibrate and make pretend it would shut off. My dad took it to the mechanic and he told us it was the computer that was fried. We bought an original rebuilt one, and those mechanical problems went away and it was smooth sailing for another four months. Mechanic said it was the same problem and we probably got a bad computer, changed that one, and reinstalled it.

Well, up until this February there haven't been much problems until it started to do the same it did two years back. But it felt worse. It would turn off and wouldn't turn on for another hour or so (imagine on the highway kicking rocks), it would very often backfire. I could feel it "shut down" but it was more like powering down and when it comes back to life BAM!! Gun shots

And there were times it would shut off and the steering wheel locks itself again, the car is dead on D, and the brake is really hard to press down, and the gas pedal is obviously dead, but then it roars back to life on its own. So it either dies and comes back by itself or it dies and i wait on the side of the road turning it on. Mechanic says once again it's the computer so we change that. And i think i've read on this forum that that is common for these Jeeps around that era.

Back to the original thing, the first time we changed the computer is when that "Service 4WD Switch" appeared and for the past two years it's been the same. The display also shows that my lights are out on the back, but they're brand new and work fine.

So i think it may be that computer, and we've made sure to order the correct one, but it keeps showing up and after this last computer change earlier this year, i'm fed up that it shows.

So two problems, that computer and that message on the display. I just really wish everything was back to normal. AND forgive me if it's too long

I'm a very descriptive person

So, after that freaking novel, you've changed out the VIC before? The VIC is what's telling you "Service 4WD switch"? If so, are you sure the one you installed was from another 2WD ZJ? If not, then that's why it's giving you that message, there's no input from the switch...

It should be, we made sure it was 2WD when asked. The mechanic said it was also. The cheapest we could find it in an emergency was a local AutoZone. Not my first choice, but it had to be done. And they gave me one for "2WD Grand Cherokee". They could have lied.

What could I do? Or where can i get another one that may work?

Personally, I wouldn't do anything. But, you could pull the VIC and make sure the connections behind are tight. Worse come to worse, look in the JY's for another 2WD ZJ that has a VIC.

Hmm, ok. Oh and i was rereading and I think i may have confused it when i said 'computer'. The problem i detailed with the result of changing out the computer is under the hood towards the left hand corner is a black box. Engine control computer i think is that. Or Module. That's what my mechanic had me change because his device kept reading that as the malfunction and the cause to my mechanical problems.

But I took the VIC you mentioned as a suggestion and i will look on that asap. I hadn't known about that. Thank you

The VIC is purely for your info only. It controls absolutely nothing. I deleted mine for a couple of switches to control my auxiliary lighting.

So do you think it might have something do to when i changed the Engine Control Unit? I googled it and it shows up as ECU, or ECM (engine control module). That message in the VIC appeared after replacing the ECU.

But we've always made sure we receive the correct one for 2WD Grand Cherokee, but since the first change it has shown up always.

Perhaps, but my money is on the VIC.

You might have a wiring problem, such as a short or a bad ground that keeps killing your ECU. They shouldn't just die, they're usually one of the last components that goes bad since they aren't really exposed to the elements and they're simple computers.

As far as I know the 2WD and 4WD ECU's 4.0, 5.2 and 5.9 would be the same, respectively, as they don't control the transfer case, just tells you if it's engaged or not. And it really doesn't do that either, that's what the VIC is for. Unless it's the V8 Quadra-Trac, then the ECU might have some control.

I didn't know you could get a Grand Cherokee in 2X4, I know you could order a Cherokee in 2WD but I thought ALL GC's had 4WD...

If your Grand Cherokee is truly 2WD only, then you're getting the light because it's the wrong VIC and there's no switch connected to the unit which is throwing the light.

Find a new mechanic.

take a look under the front and see if there is a axel there, if its a axel then its 4x4

I have the EXACT same problem with my 2WD GCLaredo. I'm a fairly proficient mechanic (built several cars from the ground up) but this has me stumped! The car functions fine, other than not wanting to start out in first from starts, and all my rear lights work perfectly. I KNOW the truck is 2WD and it will occasionally flash "SERVICE 4WD SWITCH" and is constantly saying rear lights are out. PLZ HELP!!! Thx!