cdl won't unlock - temp fix (1 Viewer)

[veggieguy]

a couple weeks ago on my 93 HDJ80, I used low range and the centre diff locked and the dash light came on as expected. After tooling around in the snow for a little bit, I put it back in high range, but the diff light did not go out and the centre diff was definitely still locked, indicated by clicking noise from the front wheels and stiff movement on turns.

I tried all the driving tricks; I put it on a lift to let the wheels freewheel; I pulled the diff fuse; I jumpered the pins on the neutral switch on the trans, but alas nothing worked.

I ended up driving with it locked for a couple weeks, hoping the ligt would go out and the diff would finally unlock, but it never did. Yes I know there's a chance of drivetrain stress and damage, but it's my wife dd and if I take it away from her too long, there's a good chance of marital stress. A calculated risk all of us DIY'ers make at one point or another.

Anyhow, I finally found more time to spend on it, and finally got it unlocked. How? By disconnecting the wires to the actuator motor and probing the pins to find out what's what (wish I had a wiring diagram!), and through some trial and guesswork I applied pos and ground to the correct pins and - as luck would have it! -the motor disengaged the diff lock and the light went out. I left it disconnected so there's no risk of it locking again, until I figure out what to do next.

Could it be the relay behind the driver kick panel? I do hear it click when I shift into low range, but not when I shift into neutral or high.

Could it be the neutral switch on the transfer case? As I mentioned I disconnected the wires and crossed the terminals on the wire to the relay (if that's where it goes?) but that didn't unlock it.

I wish I had an FSM, but does anyone have a wiring diagram and a way to identify connector pins? Or maybe someone knows what I need to replace, but I'd like to be sure before I buy parts that I may not need.

BTW, does the clicking I heard on the left front wheel verify that my birf is worn, or toast? That one leaks a fair bit of grease, but I did refill it back in the summer. How much should I be concerned?

Any advice is appreciated!

 

[Salue]

Anyhow, I finally found more time to spend on it, and finally got it unlocked. How? By disconnecting the wires to the actuator motor and probing the pins to find out what's what (wish I had a wiring diagram!), and through some trial and guesswork I applied pos and ground to the correct pins and - as luck would have it! -the motor disengaged the diff lock and the light went out. I left it disconnected so there's no risk of it locking again, until I figure out what to do next.

Do you know what wires are pos and grnd? If you wanted to lock it again, would you just do the same connection and the motor would cycle it to the lock position? Just curious as this sounds like a temp solution.

I'm not sure if the CDL wiring diagrams are the same for yours vs a '96 US Cruiser but if you do a search for FSM, it will pop up.

Good luck with figuring this out!

Salue

 

[veggieguy]

the problem with probing the wires is that I have to be under the rig with jumper leads to the battery to get 12v to the plug. Not particularly ideal when you find yourself in a driving situation where you suddenly need to lock the diff! but thanks for the fsm search idea, I'll check it out.

 

[Guambomb]

Some people have issues with their CDL switch seizing. This can present issues when trying to lock or unlock the center diff. Take a look at this:

http://www.george4wd.taskled.com/cdl.html

I had an issue with a previous 94 Cruiser not engaging the center diff which also prevented engaging the front and rear lockers. Replacing this switch resolved my issue.

I think the part number is #84222-12010 but you'd be better served calling Beno or Cdan to find out for sure. Good luck.

 

[Salue]

the problem with probing the wires is that I have to be under the rig with jumper leads to the battery to get 12v to the plug. Not particularly ideal when you find yourself in a driving situation where you suddenly need to lock the diff! but thanks for the fsm search idea, I'll check it out.

I was asking so that others might be able to use that information you provide if they are in the same situation; if they search it will be documented here.

Here's the link I was talking about:

https://forum.ih8mud.com/80-series-tech/600442-1996-fsm-ewd.html

Salue

 

[veggieguy]

you mention a switch, implying there is one, but my investigation reveals 2 switches on the rear of the transfer case, a "neutral" switch and a "low range" switch. maybe my 93 is different? in any case, I had already tried to get the motor to disengage by shorting the connector to the neutral switch with a paper clip, which didn't work. Wouldn't that close the circuit just as the switch would, and therefore suggest it's not a faulty switch? But I didn't check switch continuity, so I'll check that to be sure. thanks.

 

[Guambomb]

you mention a switch, implying there is one, but my investigation reveals 2 switches on the rear of the transfer case, a "neutral" switch and a "low range" switch. maybe my 93 is different? in any case, I had already tried to get the motor to disengage by shorting the connector to the neutral switch with a paper clip, which didn't work. Wouldn't that close the circuit just as the switch would, and therefore suggest it's not a faulty switch? But I didn't check switch continuity, so I'll check that to be sure. thanks.

Before you start shorting connectors and pulling wires, read the link I posted. It is a very good write up and has detailed pics of the switch I am referring to. Give it a shot. 99 percent sure it will fix your problem.

 

[veggieguy]

I was asking so that others might be able to use that information you provide if they are in the same situation; if they search it will be documented here.

Here's the link I was talking about:

https://forum.ih8mud.com/80-series-tech/600442-1996-fsm-ewd.html

Salue

sure, I can do that. I made a diagram of the pins I probed, but I left it at work. I'll post it soon. thanks for the link to the fsm, I'll read up and see how much is compatible with a '93.

 

[veggieguy]

Before you start shorting connectors and pulling wires, read the link I posted. It is a very good write up and has detailed pics of the switch I am referring to. Give it a shot. 99 percent sure it will fix your problem.

ok, I see which switch you mean. I thought that was just a sensor to turn the dash diff light on, since the light went out when I pulled the plug, but the motor didn't unlock. But if it also acts as a signal switch as part of the lock/unlock circuit for the actuator motor, then that could be my problem. I'll follow the procedure on the link you posted and report back my results. thanks.

 

[veggieguy]

here's the method I used to get the actuator motor to unlock the diff.

1. disconnect the connector to the actuator, it's a six pin connector with one blank pin (pin 3). I'll use this basic schematic to indicate which pins and location I refer to:

1-2-3
4-5-6

2. using jumper wires, apply grd and 12v to the following pins:

Grd to Pin 1
12v Pos to Pin 2
Grd to Pin 6

The other pins are not needed. This should make the actuator motor to run and unlock the diff. Still need to remove the diff lock switch to see if repairing that will be a permanent fix...

 

[Salue]

ok, I see which switch you mean. I thought that was just a sensor to turn the dash diff light on, since the light went out when I pulled the plug, but the motor didn't unlock. But if it also acts as a signal switch as part of the lock/unlock circuit for the actuator motor, then that could be my problem. I'll follow the procedure on the link you posted and report back my results. thanks.

I believe you have it correct that it is just a sensor for turning the dash diff light on/off based on the actuator motor part pushing the sensor in....At least that's what I thought.

here's the method I used to get the actuator motor to unlock the diff.

1. disconnect the connector to the actuator, it's a six pin connector with one blank pin (pin 3). I'll use this basic schematic to indicate which pins and location I refer to:

1-2-3
4-5-6

2. using jumper wires, apply grd and 12v to the following pins:

Grd to Pin 1
12v Pos to Pin 2
Grd to Pin 6

The other pins are not needed. This should make the actuator motor to run and unlock the diff. Still need to remove the diff lock switch to see if repairing that will be a permanent fix...

Good to know!

Cheers,
Salue

 

[veggieguy]

I believe you have it correct that it is just a sensor for turning the dash diff light on/off based on the actuator motor part pushing the sensor in....At least that's what I thought.

that's what I thought too, but Guambomb's seems to suggest that the switch will control motor operation. I did disconnect that switch which put out the dash light, but it didn't unlock the diff. Maybe it's a difference in model year? To confirm, mine is a 93 with the H/L lever and no difflock switch in the dash, just a rotator knob for the front and rear lockers.

I guess I can try what Guambomb suggests, but I have my doubts, and then it's back to the drawing board. I have the wiring diagram from the link you sent, but it's for a 96, so hopefully it's the same as a 93. Now to find time to work on it...

 

[Squash]

Could be the L to H switch is stuck? Give it a good tap, cycle the H-L lever a number of times ...your rig thinks she is still in low
Dig into the dash and find the CDL harness, use your 4way flasher switch for now, and while you are at it do the #7 pin wire.
http://www.george4wd.taskled.com/cdl.html

 

[veggieguy]

Could be the L to H switch is stuck? Give it a good tap, cycle the H-L lever a number of times ...your rig thinks she is still in low

yeah, that's what I was thinking. I shoved the lever back and forth so many times I felt guilty for being so rammy! And where is the L/H switch? there's a Lo switch and also a Neutral switch on the back end of the transfer case. I assume those send the signal for when it's in Lo and when the shifter goes back to neutral. I removed the neutral switch and fussed with it, and removed the connector and jumped the pins to fool it into thinking the switch was closed, but that didn't work. Am I missing something?

Dig into the dash and find the CDL harness, use your 4way flasher switch for now, and while you are at it do the #7 pin wire.
http://www.george4wd.taskled.com/cdl.html

Yes, a good suggestion, but shouldn't I make sure everything is working correctly before I do that mod? BTW, where in the dash is the 7 pin cdl harness? I hate to dig holes that I'll just have to fill in!

 

[Roc Doc]

I have a 94 and am in the same situation, except the 7 pin mod and CDL switch (actually it's just a hazzard light switch), have been done. you can remove the switch blanks with a pick and then you'll have visual access to where the CDL harness connector is. It's a blue connector.

Veggieguy did you have to drop the transfer case to get access to the harness connection?

 

[veggieguy]

Veggieguy did you have to drop the transfer case to get access to the harness connection?

Nope. The actuator motor harness connector goes up and over the tailstock of the transfer case, and is accessible by reaching up awkwardly with some body contortions and choice words. It's held in place with a clip which is a PITA to remove, but necessary in order to pull the harness apart. Once the connector is separated, there's enough harness length to work on the connectors.

 

[Salue]

that's what I thought too, but Guambomb's seems to suggest that the switch will control motor operation. I did disconnect that switch which put out the dash light, but it didn't unlock the diff. Maybe it's a difference in model year? To confirm, mine is a 93 with the H/L lever and no difflock switch in the dash, just a rotator knob for the front and rear lockers.

I guess I can try what Guambomb suggests, but I have my doubts, and then it's back to the drawing board. I have the wiring diagram from the link you sent, but it's for a 96, so hopefully it's the same as a 93. Now to find time to work on it...

I believe Guambomb is incorrect, if he thinks that sensor controls the motor operation. That sensor is an effect of the actuator motor locking the center diff and moving a lever that pushes the cdl sensor in, which opens the circuit, which in turn causes the lights to go on.
Maybe Guambomb meant that if you hear the motor lock but don't see the light, then the culprit is most likely the sensor?

Salue

 

[Roc Doc]

I believe Guambomb is incorrect, if he thinks that sensor controls the motor operation. That sensor is an effect of the actuator motor locking the center diff and moving a lever that pushes the cdl sensor in, which opens the circuit, which in turn causes the lights to go on.
Maybe Guambomb meant that if you hear the motor lock but don't see the light, then the culprit is most likely the sensor?

Salue

I agree. Mine is locked and the light is on which tells me the sensor is working. So now I'm just trying to see if the motor is burned up or just stuck for some reason.

 

[veggieguy]

I removed the CDL switch from the front-top of the transfer case and tested it for continuity and it seems to work. Switch is open when ball is out, and switch closes when ball is pushed in. So it seems all this switch does is turn the CDl dash light on and off. Still not sure why my motor actuator did not disengage the CDl when I shifted the lever back to Hi. Problem is I'm too scared to hook it up and try Lo range again for fear it won't release the CDl when I shift back to Hi. Not sure what I'll try next.

 

[Salue]

If you turn it on and it gets stuck and doesn't unlock immediately, you could try smacking around the actuator area with a hammer or something if it doesn't disengage? If you do that and it disengages right away, then that might help diagnose a sticky actuator motor?
Good luck with it; mine is working intermittently too but it's just too cold to go and take the actuator apart right now. I'll wait until it warms up to try to fix mine.

Salue