Toyota FJ Cruiser Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #1 (Edited)
Hi All,
Just received my 2007 FJ with an AT w/ part-time 4WD. I noticed that when I turn the key to accessory mode, the green 4WD light does not come on at all. While driving, when I shift from H2 to H4, absolutely no additional lights come on indicating that i'm in 4WD mode. When I shift to 4L, the only light that illuminates on the dash is for traction control being off. I'm wondering if this is a bulb issue or an ADD issue. If the ADD actuator is not functioning properly, will that prevent the green 4WD light from coming on in accessory mode? Any quick and easy way to diagnose the issue?

Thanks in advance for any help or insight!


Update: It fixed itself after a bunch of attempts over a few days. I believe the vehicle was not used for a month or two so it's definitely possible that this was caused by lack of use.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #3
Hi,
Thanks for the reply! I've shifted to 4H while driving multiple times at various speeds to no avail and 4L i've engaged on a dirt road a few times for at least a few hundred feet with the same result (No Green 4WD Light).
 

·
Registered
Joined
·
3,788 Posts
Are you rolling it enough for the front diff to engage?
That has nothing to do with the OP's problem; the 4WD indicator in the instrument cluster should illuminate when the ignition key is turned to the accessory position, as should ALL the other warning indicators, during the initial "bulb check" before the engine is started.

The FJ uses reliable. long-lived LEDs for all the instrument panel indicators, so the problem is not likely a failed LED.

Let me review the schematics and see what would prevent the 4WD indicator from illuminating during the "bulb-test".

You did perform the 'no-brainer' first check of verifying that ALL fuses in BOTH fuse panels are intact, correct?
 

·
Registered
Joined
·
13 Posts
Discussion Starter #5
Hi FJtest, Thank you for your reply. That is correct, I did verify all fuses are intact and not blown.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #6
So after a bit more reasearch I’m more convinced that this is an actuator issue. The vehicle is definitely not going into 4WD in either 4H or 4L. I’ll try to do some more testing when I have an opportunity to crawl under the TC to double check connections/breather hose. The only other thing I could think it would be is both 4H and 4L switches have failed which I feel is possible but not as likely as the ADD actuator which appears to be a common failure mode. I still feel like it’s strange that the 4WD light doesn’t come on during the Accessory Mode bulb check. I feel like that’s definitely indicative of something.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #7
Update: It fixed itself after a bunch of attempts over a few days. I believe the vehicle was not used for a month or two so it's definitely possible that this was caused by lack of use.
 

·
Registered
Joined
·
3,788 Posts
I checked the '07 schematics, and it's a bit convoluted.

On the A/T models, the 4WD indicator light in the instrument cluster is driven directly by the 4WD ECU, which receives inputs from multiple sensors and switches.

Regardless, the "bulb test" function when the ignition key is first turned to the accessory position should be controlled only by the 4WD ECU, and not by the input of any 4WD-related switches or sensors.

Newyorkian, you mentioned that the problem "resolved itself" and now 4WD is functional in both HI and LOW ranges; but does the 4WD indicator light now turn on during the bulb test?

The most common cause of the ADD actuator in the front diff not engaging (no 4WD) is because the contacts in the 4WD range sensing switch on the side of the transfer case get contaminated with gear oil and don't send a signal to the 4WD ECU when the transfer case gets shifted into 4WD range. I have seen this problem on multiple 4WD sensing switches. This also happens with the 4WD LO range switch, which is identical, and then the rear diff lock doesn't work.

Sometimes the contamination on the switch contacts can be temporarily dislodged by rapidly shifting in and out of 4WD range a few dozen times; this may be what happened in your case. However, because the switch interior is already oil contaminated, the problem is likely to return.

Here is a detailed analysis covering exactly how these switches fail:
 

·
Registered
Joined
·
13 Posts
Discussion Starter #9
So the 4WD light does NOT come on during a bulb test. I've tested 4WD throughout the day and it now engages every time with no issues. I will keep an eye on it over the next few months.
 
1 - 9 of 9 Posts
Top