Locate Center Differential Lock Transfer Indicator Switch

General location of Center Differential Lock (CDL) transfer indicator switch as shown in 2000 Lexus LX470 Repair manual. I found that I could get to the switch without having to jack the vehicle up. I went underneath from the right side of the vehicle.

Location of Center Differential Lock Transfer Indicator Switch (Toyota PN #84222-12010 "transfer indicator switch") for Lexus LX470

Next, I had to locate the Center Differential Lock (CDL) transfer indicator switch underneath the car. There are a total of 3 transfer indicator switches: (1) Center Differential Lock (CDL), (2) Lo gear transfer case position, and (3) Neutral transfer case position. After identifying the correct transfer indicator switch, I carefully unplugged the cable harness to it (see in picture). At this point, I did a quick test to see if I was going down the right path. I temporarily connected the 2 terminals at the end of the cable harness together with a piece of bare copper wire. With the engine on and CDL button pushed down, I now saw the CDL light turn on and saw the "Vehicle Skid Control (VSC) is off" light turn on since the ECU detects a locked center differential and, consequently, deactivates vehicle skid control.

Next, I had to remove the Center Differential Lock (CDL) transfer indicator switch. From underneath the right half of the vehicle I was able to use my 12 inch Crescent adjustable wrench to unscrew the switch. Initially, I thought it would be too tight in there to use this big of a wrench. But with a little experimentation, I was able to unscrew the transfer indicator switch fairly easily. If my adjustable wrench was not going to fit I would tried with a fixed closed/open-end wrench.

Removed Center Differential Lock Transfer Case Switch Indicator (Toyota PN #84222-12010 "transfer indicator switch")

This picture shows how the switch looks after removed and cleaned.

Now I could verify if the switch was working as it should. Per the 2000 Lexus Repair manual, using an Ohm meter, I should see no conductance on the electrical connectors with the ball left alone; I should see virtual full conductance when pressing the ball inwards. I did not observe this. My Ohm meter read 0L (0L=overload meaning very high resistance) no matter how hard I pressed the ball inwards.

At first glance, there isn't an obvious way to fix the switch. It can't be opened easily without destroying it. One option would be to simply buy and reinstall a new part. On the internet, I could get the part for $60-$70.  The local Toyota parts department sold it for $93 before tax with a one week order time.

Hypothesized Animation of Center Differential Lock Transfer Indicator Switch (Toyota PN #84222-12010 "transfer indicator switch") for LX470 from 2000 Lexus LX470 Repair Manual

Using the part diagram in the 2000 Lexus LX470 repair manual, I hypothesize switch movement in this moving illustration. Pressing the ball on sensor inwards closes an internal electrical switch.

Electrical Resistance of Center Differential Lock (CDL) Transfer Case Indicator Switch in Operation

Left: Center Differential Lock (CDL) transfer case indicator switch should have no conductivity with zero pressure at ball. Right: Center Differential Lock (CDL) transfer case indicator switch should have virtually full conductivity when ball is pressed inwards.

Upon initial removal, my transfer indicator switch measured no conductivity even when ball was pressed inwards vigorously. However, I was able to clean switch to correct this faulty behavior. I suspect that transfer case fluid sediment and deposits accumulate behind ball, preventing electrical switch from closing fully.

Cleaning the Center Differential Lock (CDL) transfer indicator switch

Cleaning the Center Differential Lock (CDL) transfer indicator switch proved to require several passes.

Obviously, I couldn't directly clean the area behind the ball. Instead, I would clean indirectly. I would press ball in, squirt some mild solvent like simple green behind the ball, hold the ball pressed inwards with a clamp, and then steam behind the ball. After my first attempt, I got a resistance of a few megaohms when I pressed the ball inwards. Better, but still in need of a lot of improvement. By cleaning in several passes, I was able to get the resistance down to 0.9 ohms (virtual complete conductivity) when I pressed the ball inwards.

Also, I found out that pressing the ball inwards multiple times during the cleaning helped as well. For example, I would squirt simple green behind the ball and then press and release the ball 4 or 5 times. Then, after steaming to rinse out the sediment, I would again press and release the ball 4 or 5 times. I suspect that this helped to agitate the sediments to break up and be washed out by the steam.

How Instrument Panel Should Look When CDL button Is Pressed

This is how the instrument panel should appear when the center differential is locked.

Before I cleaned the transfer indicator switch, the center differential would actually lock (I could hear the relay click in the front passenger footwell), but the ECU would not detect the locked condition and, consequently, would not disable Vehicle Skid Control. Even worst, the first time this happened, I drove for a few miles on paved roads with the center differential locked because the "CD locked" light on the instrument panel did not light up, a definite no-no. Thankfully, it was only a few miles before I realized something was odd when making turns on paved roads.

I hope my experience helps those with similar problems.

-Clifford Vincent Arrow
Spring 2008