Help determining lack of 4wd

[thatcabledude]

Bought a 2007 Automatic FJC with 76,000 miles. 4wd drive is not working. Hoping for an easy fix.

Here is what I got:

Pull T/C lever down to 4H, no green 4wd light at all. I can hear a relay or somthing in the 4wd ECU click. Crawl under truck and front drive shaft no longer spins freely so I know T/C is engaged.

Put T/C lever into low range and skid control light comes on and gearing changes like it should. I can also active the rear locker at this time.

At first I figured the 4H T/C switch was bad so I bypassed it with a paper clip.... No change.

If I put the truck in 4H while the key is turned to on but not running I can hear the ADD continuously beep if I crawl under the truck and stick my head near it.

HERE IS WHAT I AM NOT SURE ABOUT... If the the ADD is indeed the culprit shouldn't the green 4wd light begin blinking when the T/C in put in 4H?

I have read my fair share of threads on these issues on the "blue room" forum but haven't found anyone who mentions the 4wd light not illuminating at all when their ADD acts up.

What do ya'll think?

 

[GWcruiser]

Sticking my neck out here -- only owned my 2012 FJC a year; and never have had running gear issues so never delved into the service manuals.

Pretty sure the rear diff lock only works in low (to my knowledge). Also, with an automatic transmission, the transaxle is manual (thus the shifter), so moving it into 4H means you ARE in 4wd.

In that case, the culprit might just be a dead light bulb.

 

[thatcabledude]

Sticking my neck out here -- only owned my 2012 FJC a year; and never have had running gear issues so never delved into the service manuals.

Pretty sure the rear diff lock only works in low (to my knowledge). Also, with an automatic transmission, the transaxle is manual (thus the shifter), so moving it into 4H means you ARE in 4wd.

In that case, the culprit might just be a dead light bulb.

Yes you are correct, the rear diff lock only work in low from the factory unless hacked.

Although the T/C is manually shifted there is a lot of electronic B/S involved to activate the ADD up front. It's activation is basicly like getting out and locking your hubs in. I am definatly not getting drive from the front wheels.

I wish it was a blown bulb, but there isn't a bulb. It is actually an LED soldered into the gauge panel not to mention the light does work. It WILL flash if I pull the 4WD ecu's fuse.

 

[Delancy]

1911 has a very through right up regarding ADD failure, which it sounds like this may be.

Will find and link shortly.

 

[Delancy]

1911's ADD Thread in the Land of Sunshine and Unicorns

He'll be around here shortly, to answer any questions.

What possessed you to buy an FJC, by the way?

Surely you didn't sell the 80?

Edited:

Regarding your actual question.

I've noticed that the 07-08s do not illuminate the same way.

I don't know if the ECU is different, but a local bought a 06(07) that had the exact same symptoms, didn't afford and CEL other than the 4WD not illuminating.

Once his mechanic fixed, even when selected, but not engaged, it wouldn't blink, but stayed dead until activated, whereas my 08 will blink until it actually engages in 4WD.

For what that's worth.

 

[thatcabledude]

Thanks, I know that thread. I'm hoping the problem is those motor contacts have seperated and I can solder them back.

The main thing I really want to know is if ADD failure will prevent the green 4wd light from coming on. Most threads seem to mention that it blinks and never goes solid. Mine doen't light up at all.

 

[thatcabledude]

Hell no!! Still have the 80.

Wife wanted a Infinity FX35...... Told her the options were FJ, GX470, or Hundy. She chose FJ.

 

[Delancy]

Thanks, I know that thread. I'm hoping the problem is those motor contacts have seperated and I can solder them back.

The main thing I really want to know is if ADD failure will prevent the green 4wd light from coming on. Most threads seem to mention that it blinks and never goes solid. Mine doen't light up at all.

Read the edit above.

The three wise men should be along shortly to definitively state, though.

I've only had issues with WSS and Trac control, not ADD, so I've no clue.

 

[thatcabledude]

Regarding your actual question.

I've noticed that the 07-08s do not illuminate the same way.

I don't know if the ECU is different, but a local bought a 06(07) that had the exact same symptoms, didn't afford and CEL other than the 4WD not illuminating.

Once his mechanic fixed, even when selected, but not engaged, it wouldn't blink, but stayed dead until activated, whereas my 08 will blink until it actually engages in 4WD.

For what that's worth.

Awesome, first I've read/heard that.

Off topic........ Chris, I remember coming to the realization a while back we share the same first name, same birth date, and both have 80s. Well now I too have an FJC. Silver, of course!

 

[Delancy]

So, who's whose doppelgänger?

 

[GWcruiser]

Yes you are correct, the rear diff lock only work in low from the factory unless hacked.

Although the T/C is manually shifted there is a lot of electronic B/S involved to activate the ADD up front. It's activation is basicly like getting out and locking your hubs in. I am definatly not getting drive from the front wheels.

I wish it was a blown bulb, but there isn't a bulb. It is actually an LED soldered into the gauge panel not to mention the light does work. It WILL flash if I pull the 4WD ecu's fuse.

I learned something... thanks; wish I could be more help.

 

[thatcabledude]

So, who's whose doppelgänger?

HAHA! Not sure on that.

 

[thatcabledude]

Just got back from a test run! 4WD working perfect now!

I was able to remove the plastic cover off the ADD while still on the truck. Clean as a whistle and the and the motor connections were solid. Honestly, I was kinda bummed they weren't broken because I was hoping to do the "soldering fix."

The grease inside was extremely thick and almost crusty. I could barely turn the little motor with my fingers. I clipped some leads on the motor and toched them to a vehicle battery. For about 2-3 seconds it barely spun then it busted off and and spun like hell! Right then I knew it was fixed. Reassembled, turned truck on and and put T/C in 4H. Green light turned right on.

What Delancy stated above is correct..... The green light doesn't ever flash. It is either on or off.
(At least in and '07 FJC) That is partly what was throwing me off to begin with. I was expecting it to atleast flash while waiting for the ADD to engage. (Like a Tacoma) The light not coming on at all was making me think something else was the problem.

 

[Mtbcoach]

Well done...

 

[Delancy]

It is worth it to keep this in mind when perusing classified ads for FJCs. I have seen a few lower mile 07-08s with nomenclature "4WD not working" which can be a good negotiating point, considering the dealer charges a fortune to "fix" and some sellers may have no clue what the ADD is.

I've seen local ads go as far as saying "don't need 4WD, anyway". Haha. In Tulsa, every other car is an FJC, so a ton of used with potential to "flip" or good keepers, if that's your thing.

Couple of weeks back, there was an Sun Fusion 07 with 93k in decent condition, but potential ADD issues, as well the rear diff was on its way out for $6k.

I saw the posting two hours after it was listed and it was already sold out of state, so there are others the did see potential profit, as neither issue is that big of a deal to fix.

My two cents.

 

[thatcabledude]

Nothing like fixing something for free.

Unfortunately for me the 4wd being inoperable didn't prove to help negotiations much. Finding a lower mile FJC in silver with no rack and rear locker wasn't that easy either.