CDL & Diff Locks (1 Viewer)

[BTLSHP]

Okay, hoses are done, fluids are done as well as the harmonic balancer, water pump and some other small bits up front.

Now I am on to what for me is the mostly unknown - the 4WD and locking diffs. I have a switch for he center diff lock as I thought if my daughter gets stuck the center diff is the first easy step for traction.

When I started this morning I heard nothing pressing the center diff button or entering low range with the plug/jumper in. There is no light on the dash either. The front and rear switch yielded only flashing lights in a gravel lot. I have been reading this and others:

Troubleshooting the Toyota FJ80 Land Cruiser Center Diff Lock (CDL) -

A step-by-step tutorial on troubleshooting the Center Diff Lock on a Toyota FJ80 Land Cruiser.

www.pnwadventures.com

By the end of the day, I still had no light for the center diff but I could clearly hear the relay click in the footwell and a motor whine under the car. This was both with the switch and using low range and the plug.

There is still no center light and the FR/RR remain flashing. I will remove and test the indicator switch for the light tomorrow.

What else should I do?

For background; I doubt either low range or the lockers have been used in 7 years. Fluids are all topped off.

Thanks

 

[Broski]

If the center diff doesn’t light then the F/R diffs won’t lock.
Pull the center diff lock sending unit clean or replace

 

[Broski]

Also, check to see if the Center diff lock will lock by shifting to low range.

 

[BTLSHP]

THANKS! Shifting into low range does nothing - but I do hear noises. I will pull the sender and take a look tomorrow.

 

[Broski]

The a ball bearing in the end that can usually be freed up With cleaning and some lubrication

 

[BTLSHP]

I was just looking at pictures online. I have a 12-volt source somewhere and lots of degreaser.

Thanks again

 

[Broski]

I was just looking at pictures online. I have a 12-volt source somewhere and lots of degreaser.

Thanks again

If the ball is stuck you know that's the issue, no need for the 12- volt source.

 

[BTLSHP]

Any chance you know offhand what size wrench I need? I have a few holes in my set above 18mm

 

[Broski]

Any chance you know offhand what size wrench I need? I have a few holes in my set above 18mm

I’m guessing 22mm

 

[BTLSHP]

I’m guessing 22mm

Ha, trip to Lowe's. I will try my 24mm first.

 

[Shipwreck]

Any chance you know offhand what size wrench I need? I have a few holes in my set above 18mm

The diff lock switch is 27mm. A socket works well for the axle diffs, but can be a challenge to turn a socket wrench up in the limited space above the transfer case. I find it easier to just reach up at an angle with a crescent wrench.
An affordable replacement that is readily available at auto parts stores is the Baeck Arnley backup switch #201-1788.

 

[Squash]

Have you attempted this while driving?
Ideally some figure 8's on gravel or dirt.
If not possible to drive then jack all four tires up off of the ground.
You can hot wire the sensors with a simple "U" shaped wire.
If you hot wire a sensor and the dash lights up, then you know the circuit is good.
Do this for the CDL and then the rear locker and finally the front.
BTW I have seen double washers on sensors which make contact next to impossible. Double check.

 

[BTLSHP]

Have you attempted this while driving?
Ideally some figure 8's on gravel or dirt.
If not possible to drive then jack all four tires up off of the ground.
You can hot wire the sensors with a simple "U" shaped wire.
If you hot wire a sensor and the dash lights up, then you know the circuit is good.
Do this for the CDL and then the rear locker and finally the front.
BTW I have seen double washers on sensors which make contact next to impossible. Double check.

I took it out to a gravel lot and did several loops in low with no result. 4W Low has seen limited use over the life of the truck and none in the last few years. I have my “special” paper clip for the diagnostic port and I will try it, but may just try my large crescent on the actual sensor at the same time.

 

[landcrshr]

The diff lock switch is 27mm. A socket works well for the axle diffs, but can be a challenge to turn a socket wrench up in the limited space above the transfer case. I

Found this cheap combo wrench that fits up in there nicely:

https://www.amazon.com/BZBMGMO-Wrench-Precision-Machining-Tolerance/dp/B09QLP7DHD?pd_rd_w=L1WgI&content-id=amzn1.sym.e3825789-e6f0-4fb1-a407-ff4674fea50d&pf_rd_p=e3825789-e6f0-4fb1-a407-ff4674fea50d&pf_rd_r=5ZA3RBK0SS8GXGYW8AWW&pd_rd_wg=JPsjT&pd_rd_r=a878c500-d35c-4b93-9e0a-a1d08f27a2ba&pd_rd_i=B09QLP7DHD&psc=1&ref_=pd_basp_m_rpt_ba_s_1_sc

 

[BTLSHP]

So, I assume this is the CDL Sensor as when it is jumped as in the photo the Center Diff Lock light appears in the dash. I am struggling to get a crescent wrench on the sensor but when I did, it would not budge. It is soaking in PB Blaster and I am going out for a 27mm.

When I engage the CDL with my new button I hear both a click in the driver's footwell and a whir of a motor under the car, can I conclude that one this switch is replaced or moves freely I will have fixed the issue with the front and rear lockers not locking (just flashing on dash)?

 

[BTLSHP]

Ok, I got it off and the sensor does not respond to 12v dc current, so I guess it is dead.

 

[Broski]

Is the ball bearing moving you should be able to push it in with your thumb
Spray with the PB blaster and try and free it up.

One step at a time get the center diff light working and then try the F/R lockers again

Looking at your transfer case I wouldn’t be surprised if the sensors in the F/R lockers are in the same condition
All three are the same you might want to just get all three.

I keep a new spare in my stash.

 

[BTLSHP]

Ok, maybe I have this wrong..... I removed the sensor and I would say there was a ball bearing at the end of a shaft and when I pressed both the ball and the shaft moved inward with what I thought was considerable resistance. I am going to say total range was on the order of 3/16th's inch.

The ball did not move independently of the shaft. If it needs to I will soak it in PB Blaster

When I applied 12v dc I heard and saw nothing at all.

Thanks for your comment

 

[Mark W]

Applying current to the switch will not do anything. it is just a switch. It allows current to pass through when it is closed.

Just getting movement of the "ball" (plunger) is not the problem. In fact I have never seen on which will not move. When the TC lock (or the axkle lock) engages is HAS to move. It is just not passing current when it closes. Over time the electrical contact surface(s) within the switch can deteriorate. Sometimes burnt, sometimes just dirty with trace amounts of residue from the gear lube that is in between the surfaces every time they close. Sometimes rapidly working the plunger in and out a LOT may clean the surfaces so that the switch functions. But it will often be not long before is it balky again.

FWIW, I have not heard much negative feedback on the beck arnley or other aftermarket switches. But a few of the guys who are local to me have not had good luck with them. Getting OEM or denso units has always worked perfectly.

Mark...

 

[Irish Reiver]

It's just a passive switch so applying 12v will do nothing other than short out your volt supply. The ball bearing can seize up but with some break or carb cleaner and a lot of manipulation of the ball, it should free up.
Putting an Ohmmeter across the terminals should give you an open circuit with the ball in the normal position and a short circuit with the ball pushed in.