CDL not working (1 Viewer)

[Options20002001]

Hey guys,

I recently joined the cruiser scene and was trying to engage my center differential lock by shifting to low gear. No CDL light or ABS light comes on when I shift into low. It doesn't even come on when I'm starting the truck. I drove it around on the beach in low for a while and nothing happened. I shifted it from low to high and back a bunch of times but still nothing, so I decided to install the CDL switch to see if that would make a difference. When I push the switch, I hear the relay click, but I don't hear the actuator motor run. Anyone had this problem? Is it the relay or the actuator? Thanks for any advice.

 

[AuburnFJsexy]

A lot of times the CDL gets "stuck" and you have to turn it on and off a good bit for it to start working. A lot of these truck have never been put in low so over the years the actuator just doesnt want to work. When I bought my first 80, I had the same issue, thought the CDL was broke. I sat in my apartment parking lot at night (empty part of the lot) and just put it in low drove straight forward, pulled it out of low backed up, and repeated a bunch of times. Eventually it started to work and the more you work it, the easier it is to come on and go off.

 

[Options20002001]

Okay. Now things are a little weird. When I push the cdl switch in, the cdl and abs lights come on. I think I can feel the actuator motor running although I can't confirm this until I hear it, and my dad's out of town so he can't push the switch for me so I can hear it. However, when I shift it into low gear, the cdl and abs lights don't come on. I don't even hear the relay click or feel anything. The lights will come on in low gear if I push the cdl switch but not if I shift it. I thought this only happens if I do the 7 pin mod which I've never done. The previous owner might have but I doubt it since my dad bought the car when it had 40k miles.

 

[yohavos]

You are correct regarding how the 7-pin mod works. I doubt the truck has it done, though.

The good news is your actuator works. That's expensive. Everything else is pretty straight forward.

There's a sensor on the side of the t-case towards the back (L4 Position Switch) that could be your culprit. Check to make sure it's plugged in.

When you put the truck in low range, this sensor tells the system to lock the CDL.

When the CDL locks, another sensor turns off your ABS and lights up the dash for you.

If the sensor is plugged in (nothing looks out of place) you can test the wiring pretty easily.

With key "on" (vehicle not running, in park, etc.)

Unplug the sensor and jumper it with a paperclip. This should close the loop (what the sensor would do if operating correctly, and you put the truck in L) and in turn lock the center diff. You'll hear the actuator.

If this works, the issue is probably with your sensor.

Another step to troubleshoot is to remove the sensor and push it in by hand (same conditions as mentioned above) to simulate it going into L.

Many times these can be cleaned up and will work. If not, it's a cheap part through Rock Auto, I believe.


Here's a picture I took when testing my CDL sensor (same idea, paperclip jumper)

This picture was taken from the front of the truck. This is NOT the sensor you're concerned with.

 

[Options20002001]

Thanks guys. Lots of helpful information. I'll check the sensor tomorrow and try the paperclip and tell you how it goes. So the sensor is only used when shifting into low gear? That's why the cdl works if I use the switch?

 

[yohavos]

Thanks guys. Lots of helpful information. I'll check the sensor tomorrow and try the paperclip and tell you how it goes. So the sensor is only used when shifting into low gear? That's why the cdl works if I use the switch?

Yup.

The L4 Position Switch is triggered when you physically shift the H-N-L lever into Low. It tells the center diff to lock.

Before the 7-Pin mod was given to the world (early write up is contributed to Cdan I think?) people used to unplug this sensor on purpose. I think the shift points are different (and O/D is still used, maybe?), which is why the 7-pin mod is preferred.

 

[Options20002001]

So I jumpered the sensor with the paperclip today. The cdl and abs lights didn't come on. But the A/T P light came on every time I jumpered it regardless of whether it was in hi, lo or neutral. I know the bulbs aren't bad because they come on if I use the cdl switch. I don't know why the cdl doesn't engage in low

 

[ppc]

You jumper the wrong connection. That was the neutral position sensor that was located in the 10 o'clock position as you look to the front. The 4LOW is at 1-2 o'clock position. The CDL indicator sensor is on the front of the transfer. The CDL can lock and not show the dash lights if that sensor is malfunctioning.

 

[Options20002001]

I got it working. I just cleaned out the sensor and everything's working now. Thanks for the help

 

[Biggreener]

I got it working. I just cleaned out the sensor and everything's working now. Thanks for the help

Got it cleaned out how? I'm having this same issue on both my rigs...

 

[Options20002001]

Got it cleaned out how? I'm having this same issue on both my rigs...

Take the sensor out and spray the "springed up" ball with a cleaning fluid (like brake cleaner) while rotating the little ball in its socket. Then push down on the ball and spray some more fluid. Rotate the ball again. Let it go and repeat the process a few times. Check the switch for continuity before installing. It is closed with the ball pushed down.

Hope this helps.

 

[Kennyfzj80]

Got it cleaned out how? I'm having this same issue on both my rigs...

You can also buy new sensors. I've had trouble with this recently.

They are cheap enough. If you do a search on this forum, there is a list of compatible sensors made for other toyota cars, that cost way less.

 

[Biggreener]

You can also buy new sensors. I've had trouble with this recently.

They are cheap enough. If you do a search on this forum, there is a list of compatible sensors made for other toyota cars, that cost way less.

Pulled it, cleaned it, put 9v power to the connectors to "clean" the electrical portion of the switch, etc. still no love. I came across the list of aftermarket replacement options and found one at my local O'Reillys for 23 bucks, awesome info thanks again

 

[leucadiacruiser]

Thanks folks - Had the same issue in my '94 FZJ80 after putting in my CDL switch. Did the paper clip jump and was happy to see diff lock lights on. Replaced the sensor, but then the diff stayed on - even after driving, turning off and backing up, etc. After doing laps between the driver seat and under the truck to the diff to try to figure out what was going on, my brother in law stopped by. He manned the CDL switch while i juggled the wires at the diff sensor actuator and voila - looks like it just took some massaging to wake up 20 years of never being activated. All good now - just need to find time to use it!

 

[LCG]

Have problem with my 4wd not engaging hence trying to read up on it and came across your post. CDL light on dashboard does not light up either when button pressed or when 4l engaged.

Stupid question as certainly no mechanic/electrician.

What does shorting the sensor do?? I have shorted that sensor on my transfer case and a clicking can be heard by the steering wheel but no light or any noise from actuator/transfer case. Does this mead the switch works and the actuator stuck? Or there is problem with electric and not sending signal to actuator????

Many thanks

 

[Michiana4x4Toyotas]

Sorry to bring a thread back from the dead...but ive been tossing darts at my cdl problem...

1. fuse is fine
2. relay is clicking
3.did the 7 pin mod AND installed oem cdl switch
4. checked ALL sensors for continuity and passed
5. took actuator motor off-gears where free and brushed appeared clean

cant hear motor working and lights on dash dim for a split second (indicating a power drawl) but no movement from motor and no dash lights

ideas?

 

[Rifleman]

Michiana4X4toyot, So your saying that you hear the motor run but it just won't engage the center diff lock. So was everything working right with the enter diff lock before you did the mods? One last question, when you had the actuator out of the truck did you test it like the FSM says to do with a small battery? If you did, did you see the actuator gear/shaft turn freely in both directions while under power?

 

[clubted]

I also had similar issues with my new to me last December FZJ80. 114k and never offroad by the previous owner so I doubt in it's never been used in L4. I installed the CDL switch easily enough but the light just wouldn't come one. Took a few trips around the block, shifted between L and H a few times over a few days and now works like a charm. Lack of use the probable cause.

 

[smoothcruiser]

Take the sensor out and spray the "springed up" ball with a cleaning fluid (like brake cleaner) while rotating the little ball in its socket. Then push down on the ball and spray some more fluid. Rotate the ball again. Let it go and repeat the process a few times. Check the switch for continuity before installing. It is closed with the ball pushed down.

I'm having a helluva time taking the sensor out. It seems my wrench is too long to get any leverage given surrounding obstructions. Is there some trick to this? Just to make sure, is 27mm the right size wrench? Thanks.

 

[ghosttowner]

This sensor switch is truly a finicky one. Today I received the two sensor switches that I had ordered from Rock Auto and was going to just replace the original ones. However, before going through the trouble of replacing them, I decided to give it one last try. I drove the truck back and forth in Low range, with the CDL switch on and off, made a few small turns, and to my joy, suddenly the turns became heavy and all the lights on the dash sprang into action. I am still going to go ahead and replace with new switches anyway, and keep the old ones as spares after some cleaning. Also plan to religiously exercise the diffs at least once a week before it forgets what it was designed to do.