4WD Hi doesnt work

[dierte]

Hey guys,
I'm looking at picking up a '97 4Runner 5sp w/ 121k on the clock. The owner informed me that 4hi quit working but 4lo still functions. I haven't gone to look at it yet but wanted to here from everyone what it might be. Any suggestions would be great.

 

[Quadsbc]

Did you test it or are you going just by what the previous owner said? 2x check 4lo is 4lo and not 2lo first.

 

[Asaspades93]

Could be a bad vacuum or vsv

 

[dierte]

Did you test it or are you going just by what the previous owner said? 2x check 4lo is 4lo and not 2lo first.

I'm going to look at it probably tomorrow. What are some tests I can do to see what's functioning properly and what isn't.

 

[TheDurk]

Could be a bad vacuum or vsv

Disagree. Then there would be no 4L either. Assuming there IS good 4L with ADD and T/c both engaged. You should confirm this first of all, as Quadsbc said. Drive 50 feet in a curve and you will feel it.

Most likely is 4H detection switch on the TC or it's wiring. Relatively easy fix. This happened to me when somebody effed up a clutch job and broke the connector on the 4H detection switch.

Only sure test is by-pass the switch and see if it engages ADD. You should first confirm TC engages. Front propeller shaft aka drive shaft should turn by hand in 2wd, and then lock up with 4H engaged and engine off (no vacuum for ADD). Then start engine and bypass switch. Drive car a little to feel if 4H truly engaged. On asphalt, slow speed, you will know right away as it will bind on any curve and 4wd light will come on.

You can get to the connector through the shift hole or access the wiring at the ADD relay in the right hand kick panel. In either case, ground the blue wire. (The above assumes 5-speed '97 J-shift same as my '99 5-speed J-shift. I think it is.)

I really don't think it can be anything else if 4L truly works. Detection switch is the only difference in the circuit between 4H and 4L.

 

[ajonesnv]

These systems get gummed up when not maintained too. My buddy bough a 00 with a similar issue and we got it working after "breaking it in" and then flushing the fluid.

Edit: His was the AWD button model, so it may not apply.

 

[dierte]

Disagree. Then there would be no 4L either. Assuming there IS good 4L with ADD and T/c both engaged. You should confirm this first of all. Drive 50 feet in a curve and you will feel it.

Most likely is 4H detection switch on the TC or it's wiring. Relatively easy fix. This happened to me when somebody effed up a clutch job and broke the connector on the 4H detection switch.

Only sure test is by-pass the switch and see if it engages ADD. You should first confirm TC engages. Front propeller shaft aka drive shaft should turn by hand in 2wd, and then lock up with 4H engaged and engine off (no vacuum for ADD). Then start engine and bypass switch. Drive car a little to feel if 4H truly engaged. On asphalt, slow speed, you will know right away as it will bind on any curve and 4wd light will come on.

You can get to the connector through the shift hole or access the wiring at the ADD relay in the right hand kick panel. In either case, ground the blue wire. (The above assumes 5-speed '97 J-shift same as my '99 5-speed J-shift. I think it is.)

I really don't think it can be anything else if 4L truly works. Detection switch is the only difference in the circuit between 4H and 4L.

Thanks. The clutch was recently replaced so this may be issue. I'll do some poking around.

 

[TheDurk]

Thanks. The clutch was recently replaced so this may be issue. I'll do some poking around.

Yeah, it's easy to bash that switchhead against the underside of the truck as you're wrestling the bell/trans/T-case combo in and out (or out and in) of the truck. Or just forget to plug it in. I think it's on the right side, but it any case it has a blue wire.