4wd Light Mystery

[TF88FJ62]

Basics: 88 FJ62 with about 135k miles. Only had it for about 2 weeks and still learning her quirks.

Problem: neither the 4H transfer button light nor the 4WD light on dash come on when the car is in either 4H or 4L. The 4H light came on once when in 4WD, then went out. I tapped it a few times and it came on/off, but that trick hasn't worked since. I caught the dash light come on once - can't remember if I was starting the car - and it hasn't since lit up since.

What I've done:

• Read a ton of threads. You guys are awesome
• Looked for both lights during start up - nothing
• Checked the drive shaft...seems like 4WD works. I climbed underneath and this is what i found:
  • With the truck in 2WD, drive shaft moves freely.
  • I pressed the 4H button, drive shaft does NOT move and neither light shows up.

So this tells me 4WD works, right?

While I was under the truck, I do some looking around. Besides clearing out what looked to be a (vacant and old) rats nest, I found a hanging, disconnected wire. I am having problems posting pictures, so let me try to describe the problem. There are two sets of braided wires that appear to come down from the top of the transmission. The pair that isn't cut, connects to a post about two feet further towards the rear. I have no idea what the post is for. I searched around for the other end of the cut wire and I cannot find a logical home. Could this have something to do with my problem?

Thanks.

 

[pandathrust]

look around the transfer case and see if there are any cut or mangled wires connecting there. One of the wires that go to the TC is the 4H light. My brothers 4H light did the same sort of thing. It flashed and sometimes even stayed on when the TC was obviously in 2WD. After fixing the mangled wires and wrapping them up with some electrical tape, the 4H button/4WD light worked perfectly. I would check those wires and try to trace them back and see if there is any cut or messed up sections of wire. You might wanna post some pics up of the wires of the transmission your talking about too.

 

[Output Shaft]

If you tapped the indicator light on the dash in the past and it flickered on & off... The problem is a loose bulb.
(Or at least one of the problems)

 

[Super77]

I'm not quite following your troubleshooting process, but Output Shaft seems to make sense when he mentions the bulb. On my 62, one of the vacuum switches activated by the 4WD button went out. There's plenty archived on 'Mud about that fix. Maybe include checking those as part of your process? They're mounted to the upper firewall, between the wiper motor and the transmission tunnel.

If you do need a new vac switch, mind the fact that the exact replacements are $$$$$, but Toyota pickup version + 5 minutes of Dremel time is ~$20.

 

[TF88FJ62]

If you tapped the indicator light on the dash in the past and it flickered on & off... The problem is a loose bulb.
(Or at least one of the problems)

it only flickered once out of like 30 plus tries. I hope it is the blub.

 

[TF88FJ62]

Basics: 88 FJ62 with about 135k miles. Only had it for about 2 weeks and still learning her quirks.

Problem: neither the 4H transfer button light nor the 4WD light on dash come on when the car is in either 4H or 4L. The 4H light came on once when in 4WD, then went out. I tapped it a few times and it came on/off, but that trick hasn't worked since. I caught the dash light come on once - can't remember if I was starting the car - and it hasn't since lit up since.

What I've done:

• Read a ton of threads. You guys are awesome
• Looked for both lights during start up - nothing
• Checked the drive shaft...seems like 4WD works. I climbed underneath and this is what i found:
  • With the truck in 2WD, drive shaft moves freely.
  • I pressed the 4H button, drive shaft does NOT move and neither light shows up.

So this tells me 4WD works, right?

While I was under the truck, I do some looking around. Besides clearing out what looked to be a (vacant and old) rats nest, I found a hanging, disconnected wire. I am having problems posting pictures, so let me try to describe the problem. There are two sets of braided wires that appear to come down from the top of the transmission. The pair that isn't cut, connects to a post about two feet further towards the rear. I have no idea what the post is for. I searched around for the other end of the cut wire and I cannot find a logical home. Could this have something to do with my problem?

Thanks.

Here are the pictures!

 

[RJC409]

Did you ever figure out your problem?I have the same issue, in that neither of mine lights are working but the 4wd engages.

 

[SteveH]

FWIW - the long 'L' shaped bracket with the sensor adjacent to the driveshaft is part of an aftermarket cruise control system, do don't be confused by that pair of wires.

 

[TF88FJ62]

Did you ever figure out your problem?I have the same issue, in that neither of mine lights are working but the 4wd engages.

I changed the bulbs in the 4h button and the 4wd indicator in the dash. Both work...but still have same problem. Now the 4wd light stays on the 4 seconds when I turn off the ignition. Got me.

 

[CaptHamster]

I'll add in my personal experiences here:

Had an issue where 4WD was confirmed working, yet the 4WD light was not coming on in either 4HI or 4LO. On the passenger side of the transfer case (and some on top) there are 3 electrical switch plugs that perform various functions. One of those, on the right hand side, is the 4WD indicator switch, which simply controls when the 4WD light comes on and goes off. Tested the switch, came out bad, so I bought a new one; you should still be able to buy one from Toyota (although sort of expensive, ~$100 I think?)

For me, this resolved the issue of the light not working, but then started a new problem. After having the light on and driving, at random and varying times, I would blow the 15A gauge fuse and lose all my gauges, heat and A/C. I tested the switch to make sure it was within specs, and it was. I drove around for quite some time before I finally got back down there and poked around; I quickly realized that the wiring harness that those plugs and switches all plug into, had lost its plastic sheathing, causing wires to contact each other or the body, blowing that gauge fuse. Wrapping some electrical tape and insulation around the bundle of wires resolved the problem for me and now the light works reliably without flickering or blowing gauges.

Attached is a scanned page from the FSM showing all the different plugs for the FJ62 transfer case; this should help identify what's going on down there.

As for you, look at the picture you took of that strange post thing; just next to it, bolted to the body, is the ground wire for the transfer case; I would undo that and clean the contact area and both ends of the wire first, to make sure it's not just a bad ground causing the issue. If that fails, check the wires coming out of the 4WD Indicator switch; mine were pulled pretty taught on the original and had almost disintegrated. If that's the case, you might want to look at getting a new switch. Also check the bundle of wires where they all meet just above the transfer case, if any of those are uninsulated, they could be grounding through something else or shorting.

Oh, and I'll bet you changed that 4WD light bulb with an LED light...mine does that same staying on for 4 seconds after shutting down thing that yours does. I don't really know why, I just think there's a low enough current running through that system that it lights up the light bulb. Stops as soon as I put a regular incandescent bulb in. Doesn't bother me, it's worth it to have a bright 4WD light anyway.

Hopefully this all helps, and good luck! Frustrated the hell out of me for a long time...