Ye olde "Serv 4wd" light (again)

[LKelly]

Well, got the Power Wagon stuck again today - had to put a call in for help, and get some extra folks out to help get the truck out. Luckily we got it out before dark, because I don't like to leave the truck out in the woods overnight...I always figure I'll get back and it'll be stripped, though I suppose that's unlikely when I drive trails that see one or two trucks a year.

Anyway, I had my 'normal' problem with the lockers & swaybar, which I reported before on another forum maybe a couple of years ago. Under nearly all conditions, the swaybar & lockers work great - but if I shut the truck off with the lockers locked & swaybar disengaged, when I start it back up there's about a 50/50 chance that the locker & swaybar lights will all be flashing and the "serv 4wd" light is lit. Normally I work around it by not turning off the truck with the lockers locked, but when it takes you 3 or 4 hours to get your truck unstuck that's a long time to let it sit and idle.

Anyway, I was just wondering if anyone has any new ideas or has experienced this problem. As far as I can tell, it doesn't seem to be an issue with any of the connectors or the lockers themselves...and as I mentioned, everything works great until the truck is shut off.

I did have one new experience this time - at one point after I'd been stuck an hour or so, I got back in the truck and started it to run the air conditioning for a while. At first I had the normal 'serv 4wd' light situation, but after it idled for about 5 minutes or so suddenly the 'serv 4wd' light went out and the locker and swaybar lights stopped flashing and went back to how they were supposed to be. If anything, that made me even more confused by what the problem could be. I wasn't moving the truck when it happened, and it was just sitting there idling in Park...and it certainly didn't roll or anything, considering that the front end was buried to the point where you couldn't see the front bumper.

On a positive note, I learned that I can jack up the whole front of my truck with my hi-lift using the crosstubes on my brushguard...but I really really really wouldn't recommend doing it unless you're desperate and willing to damage your truck to get unstuck. But, when your front bumper is underground you end up working with what you have. I don't think I damaged my brushguard (or truck) too badly, but I didn't get home 'till after dark - so I guess I'll find out tomorrow.

[cruz]

Under nearly all conditions, the swaybar & lockers work great - but if I shut the truck off with the lockers locked & swaybar disengaged, when I start it back up there's about a 50/50 chance that the locker & swaybar lights will all be flashing and the "serv 4wd" light is lit.

I'm unclear on one point, is it just lights flashing and swaybar/lockers working, or lights flashing and swaybar/lockers not working?

[w2dodge]

i can tell you this ...my 05 the lights would go on after a long trip on highway,driving around town no...after the lights were on shut the truck off...few hours later they were on for a couple of seconds then they went off...i changed the diff oil front and back cleaned the magnets ,with the diff covers off put the lockers on in my driveway and watched them engage and drove it back and forth in driveway and street..went turkey hunting boom it happened again,this time i brought it to the dealer waste of time..anyway they had it for 5 weeks and did nothing , parts and tools they didnt have..so searching dt i did the dielectric grease magic..found my front and rear locker plug had moisture on them..cleaned them dried them and also the transfer case censor,sway bar also and zipped tied it tight...had the truck on the ball field yesterday everything engage like a light switch...dealer wanted to change swaybar and rear actuator..i test them once a week..so far knock on wood

[GunniPWguy]

Dry is key! Any slight bit of moisure in there will send the electrical gremlins out to play. Since I had everything replaced (entire swaybar assy, new actuators, new plugs, new carrier bearings. etc. etc.) I have my connectors dielectric greased, siliconed, and fluid filmed. Haven't had any issues since. knock on wood

[LKelly]

I'm unclear on one point, is it just lights flashing and swaybar/lockers working, or lights flashing and swaybar/lockers not working?

Well, I know for sure that the swaybar was still disengaged...the lockers are a little harder to tell, though since it was still spinning all four I assume they were also still locked. However, since the front end was hung up on the bumper and axle it might have spun all 4 tires anyway ('cause of the limited-slip in the rear and having no weight on the front tires).

I already went through all the electrical connections with the dielectric grease, but that didn't seem to help the problem with getting the "serv 4wd" after shutting the truck off. I can go through them again, it certainly wouldn't hurt...and I'll also run some experiments, to try to determine if it's the lockers or the swaybar that's the problem. If it's the swaybar, I might just disconnect it mechanically and stop using the disconnect switch - since my truck is never driven on the highway anyway.

This has been a problem with this truck for at least 3 years, and it seems like I've gone through everything...and since everything works fine 90% of the time, it'd be hard to justify spending the money on a new smartbar or something major like that. Perhaps there's some easy way to maintain current to the lockers/swaybar when the truck is turned off...though I dunno how many amps that'd draw. Maybe I can rig it up to a switch on the dash, with the options of "stuck" and "not stuck".

[GunniPWguy]

I have also experienced the serv4wd light after stopping to take a picture(leak) and turning off the engine without disengaging locckers and reconnection of swaybar. The light went off after I went through the whole sequence again. It would be nice to not have to mess around with disengaging lockers and engaging the swaybar every time you want to stop the truck and turn off the ignition. Seems counterproductive.

[LKelly]

Well, I checked out the truck this morning and didn't find much damage to the brushguard - just a bit of a dent in the bottom of the tube where I put the hi-lift. I jacked it up right next to the side plate, because I knew that the tube would bend like a noodle otherwise. I was sorta hoping that it would straighten out the guard so that it wasn't crooked anymore, but it doesn't look like it helped.

[GunniPWguy]

Damage done. So I was out camping this weekend and forgot to re-engage the swaybar before turning off the truck. Sure enough serv4wd was on when I got back in. So i drove it out re-engaged the swaybar and the serv4wd went off shortly thereafter. Annoying!

[bones]

Damage done. So I was out camping this weekend and forgot to re-engage the swaybar before turning off the truck. Sure enough serv4wd was on when I got back in. So i drove it out re-engaged the swaybar and the serv4wd went off shortly thereafter. Annoying!

My '05 used to do it as well. I think it is by design, whereas when you start the truck back up, the computer expects everything to be back to normal position (lockers unlocked, smartbar connected). But since the truck was off, the smartbar is still disconnected and never had a chance to go back to connected. I don't think it's really an issue unless the lights stay on or start blinking abnormally.

[LKelly]

My '05 used to do it as well. I think it is by design, whereas when you start the truck back up, the computer expects everything to be back to normal position (lockers unlocked, smartbar connected). But since the truck was off, the smartbar is still disconnected and never had a chance to go back to connected. I don't think it's really an issue unless the lights stay on or start blinking abnormally.

My main concern is that it usually happens when I'm stuck, and need some wheelspeed to get out - and if I don't know for sure if the lockers are locked or not, I worry that they'll try to lock while I'm spinning the tires. I've never had any luck unlocking them and reconnecting the swaybar to fix the "serv 4wd" problem - but that's probably because I'm stuck, so I can't move the front suspension enough to reconnect the swaybar.

I still need to run some more experiments, but at this point I'm 90% sure that it's the swaybar that's the problem...and I agree that it's probably a design issue, rather than a problem with the electrical connectors or something like that. For now I'll probably just not use the swaybar disconnect when I think I might get stuck, though usually I don't know if I might get stuck until it's too late.

[LKelly]

I have a little time, so I figured that I'd post my findings so far on the relationship between shutting the truck off and the "serv 4wd" light.

Thus far, I've been able to duplicate the problem pretty easily by shutting the truck off with the swaybar disconnected - it seems to happen perhaps 50% of the time, depending on how level the front of the truck is sitting. When the truck is first started, the "connected" light flashes for an instant before the "disconnected" light lights up...but when the "serv 4wd" light kicks on, the "disconnected" light is on solid and the "connected" light is flashing. If I'm not stuck, I can fix the swaybar lights by hitting the "connect" button and moving the truck enough that the swaybar can hook back up - but the "serv 4wd" light remains on. And, while the "serv 4wd" light is on the truck won't allow me to lock the lockers or disconnect the swaybar, as it appears to force the unlocked/connected condition.

When I tried starting the truck with just the lockers locked, sometimes the truck would start up and engage both lockers and sometime it would only engage the rear locker - and the front locker light would be blinking, until I moved the truck a little and it would lock back up. Even if the lockers won't lock upon starting, it doesn't appear that the lockers will make the "serv 4wd" light come on - only the swaybar seems to trigger that issue. But, once the "serv 4wd" comes on the truck won't allow me to lock the lockers - it forces them to unlock. So, even though the lockers aren't an issue they get trapped in the black hole that is the smartbar.

At this point, my temporary solution is to stop using the swaybar disconnect - because in the great scheme of things a disconnected swaybar will make a lot less difference on the trail than having lockers that actually lock. It does appear that the truck unlocks the lockers when you shut it off, or at least the indicator lights make it appear that way. If I shut off the truck with them locked and then turn the truck back on, the 'unlocked' light lights up first - followed by the "rear locked" light, and then sometimes the "both locked" light (it either locks the front or blinks the light like it's trying to). If I'm stuck, I can very slowly spin the tires until the front locker locks up...though sometimes this is inconvenient, as spinning the tires just means I'm digging myself in deeper.

My current guess is, even if I came up with a system to keep the lockers locked while the truck was shut off, it'd probably just freak out the second I started the truck...or I'd burn out some of the electronic doodads and need a new smartbar.

I'm guessing it's some sort of issue in the programming, where upon startup it checks the status of the smartbar - and if it's disconnected and won't reconnect it triggers the "serv 4wd" light. It seems like a bit of a glitch, because the system should be smart enough to realize that if you last ran the truck with the bar disconnected it'll probably still be disconnected when you start the truck back up. I wonder if all PWs have the same issue, or if this problem is mainly with the early trucks and they resolved it later on in production?

[LKelly]

Of course, as soon as I wrote the above post my truck decided to give me the "serv 4wd" light for just the lockers...guess that shows me for posting before I was done with my experiments.

[GunniPWguy]

It is irritating. When mine stop working because of electrical issues again. The manual swaybar disconnect and hardwired locker project will become reality.

[LKelly]

It is irritating. When mine stop working because of electrical issues again. The manual swaybar disconnect and hardwired locker project will become reality.

Yeah, I've been thinking the same thing - just hardwire the lockers and separate them completely from the smartbar system. Then I could just use them when I wanted to, and wouldn't have to worry about the whole high-range/low-range thing either. I'm a mechincal guy - not an electronics guy - but it seems like it'd probably be easier to hardwire the lockers than to get the smartbar to start working the way I think it should.

I eventually got the lockers to act up by putting enough strain on the diffs so that they couldn't unlock when the power was turned off - but even doing that it took quite a few tries before it worked. Basically I locked the lockers and then parked the truck on a steep hill, letting it roll back until it was held by the transmission being locked in 'park' - that way the axles were holding the truck instead of the e-brake. Eventually that worked, though the indicator lights on the dash were a bit different from those of the swaybar disconnect - the "unlocked" light was lit up solid, and the front/rear locker light was flashing (just like when you first try to engage the lockers). Turning the dial back to 'unlocked' solved the blinking light issue, but the "serv 4wd" light stayed lit for quite a while...even after I put the truck back in 2-high.

So, when the swaybar messes up the lights indicate that it's disconnected (which is correct) and is trying to reconnect (being forced by the serv 4wd condition). But, when the lockers mess up they indicate that they're unlocked (which is incorrect) and that they're trying to lock (which they already are). No idea why they're different, but perhaps next time that'll help me diagnose the problem. Either way, it seems like most of the time I've had problems it was probably caused by the swaybar disconnect...at least from the symptoms I've seen.

[trk4sale]

My truck does the same thing. The 7/70 warranty expired this month so it's time to re-wire the lockers.

[w2dodge]

Does anyone have a hard wired system on a diagram...?

[w2dodge]

Does anyone have a hard wired system on a diagram...?

[GunniPWguy]

Whoever comes up with that schematic needs to put a patent on it. The locker hardwire bypass harness kit could be a money maker someday IMO

[w2dodge]

Geez this HTC phone blows...second time submitted 2 of same reply...I hope someone comes up with diagram ...I have no patients with electronics and wires

[FirerescuePW]

Total of 4 wires on each diff plug. Black and White are for engaging the lockers. White is +, Black is -. Switch the + with a toggle or rocker switch, or better yet with a relay controlled by said switch. There is a thread on DT about it. Search hardwired lockers.